Pedal Powered Boats [Archive] - Page 5

spidennis

10-11-2010, 04:23 PM

I plan to enter the 1200 mile Ultimate Florida Challenge in March 2012
http://www.watertribe.com/

Below is my first model/mockup of my design, a freestanding biplane rigged folding catamaran. In the first pic you'll see my oars but I'd like to set up a peddle prop drive.
In the second pic the boat is setup for the 40 mile portage.

Some competitors walk this route and push/pull their portage carts while others use a bicycle to tow it. I want to tow it, if i can.

Or, I'd like to use the same parts for both the prop drive and for the bike, or turn the boat into a bike, or some combo of this nature.

If I left the bike whole, and the bike was always ready to go, when I re-provision for water/supplies then I'd have an instant and quick ride. Towing is easy this way? and maybe set it up like some of the water bikes for while on the boat?

Anyway, I got a few different ideas rolling around but my plan A is to use oars and the bike to tow. A prop drive would require a bunch of designing, testing and cost .... I've been on the thread quite a bit, and studying it a lot .... but I'm willing to accept all advice and suggestions!

I might have to make a separate thread for this, but I wanted all that are subscribed to this thread to see my request .
edit: ok here's the link to this thread:
http://www.boatdesign.net/forums/boat-design/ultimate-florida-challenge-boat-2012-a-35041.html

http://www.sandslave.com/ufcboat/oarswheelssailsready.jpg

http://www.sandslave.com/ufcboat/portagemode.jpg

cthippo

10-11-2010, 08:20 PM

I know I'm coming into this a bit late, but I had an idea the other day for a human powered boat and I was wondering if anyone was looking into it.

I was envisioning one of those twin hull rowboats converted to a paddle-wheel design with the paddle between the hulls. Tonight I was considering the relative advantages and disadvantages of the paddle-wheel design and remembered another kind of pump I have seen.

Are you familiar with a Tesla Turbine? It consists of a series of plates spaced very close together rotating on a common shaft, something like the platters on a hard drive. The discs are spaces about twice the boundary layer thickness apart and so the adhesion of the water at the boundary layers drags the water along with the plates. There are several designs, one of the more common of which being a center fed centrifugal one. Tesla turbines can be extremely efficient, but work best over a narrow range of operating parameters.

For a human powered boat which will have a relatively limited RPM range at the shaft and a fixed fluid viscosity, it seems like this may be a viable system.

I57

10-12-2010, 01:51 AM

Dennis A
Sorry about the delay in replying, been travelling and back in internet range. The dipping rudders are at a fixed angle, I need to adjust mine as boat is slow at turning. Catch is if angle is greater it gives better turning but slows the boat more when trying to go straight. Am going to fit a small trim tab for straight running and angle the dipping rudders more.

Ian

chilihead98

11-19-2010, 01:29 AM

Hey everyone, I came across a really great source of foils to use for my purpose. A friend of mine is into sailboarding and in this sport the boards have a fin. Because sailboarding has such intense interest and the people who do it are very competive there has been a lot of development of all aspects including the fins used. They are interchangeable and most boarders end up with quite a few of them. But because of the rapid advances in the sport the fins become obsolete quickly and so the older ones, even though often in great condition, can be picked up quite inexpensively. I rigged up one to try on the back of one of my canoes, simialar to the Pacific Tailboats, and it worked better than I expected. So anyway, I think I will begin developing a pedal drive using one or two of these fins.

Cool! :cool:

Fins are fun.

Tom McGuinness
Pacific Tailboats

spidennis

11-19-2010, 06:26 AM

Tom,
So just what is Pacific Tailboats up to ?
I checked the website .....
looks like it needs updating,
the "news" is from 2006?
Tell us more!

chilihead98

11-19-2010, 02:21 PM

Tom,
So just what is Pacific Tailboats up to ?
I checked the website .....
looks like it needs updating,
the "news" is from 2006?
Tell us more!

Things are pretty much in a state of "suspended animation". I've completely redesigned the tailboat for commercial production...it's now much more attractive than the prototype. Our US patent for the boat issued in 2006. In early 2007, I took delivery of metal parts for approx 100 boats. A new sit-on-top hull has been designed and prototyped at full scale. For improved manoeuverability, the new hull does not have the integral skeg present in the stock Necky prototype hull. It also has plenty of rocker plus a retractable dagger board ahead of the drivers seat...which provides a point of focused lateral resistance like the dorsal fin on a shark, thereby minimizing side slip during turns. I've researched fin materials and suppliers but haven't pulled the trigger yet. I've also not had any shop space to work on the project during what little spare time I've had...this is the biggest hold-up.

In late 2005, I started working on a large project for Chevron and ever since have been busy as a pair of jumper cables at an Alabama wedding. LOL!! It's been frustrating not to be able to make much progress on the product since late 2006. However, I can assure you the project is neither forgotten nor abandoned. :)

I'd be interested in licensing the design and/or teaming with another builder to complete the project.

Kind regards,

Tom

I57

11-19-2010, 10:38 PM

chilihead98

11-19-2010, 10:52 PM

Chilihead98
I am thinking of fitting a fin drive to the hull of my first pedal boat. It is 5m long, 500mm beam and is a sit in boat. The stability is marginal and I have used stabilisers for it. With a fin drive I could sit much lower in the seat and maybe not use stabilisers. What size fin would you need and what sort of speed can you expect out of it.

Ian

Ian,

I expect you should be able to achieve displacement hull speed.

The stock Necky hull used for the prototype had a beam of approx 35 inches and was 13 ft long....rather barge-like, but could still cruise along a 4.0 mph...which was faster than two adults would normally paddle the same hull. A narrower and longer hull will undoubtedly go faster.

The hull should be designed to suit your mission objective. If you want straight-ahead speed, then long and narrow is the way to go. However, if you want enhanced maneuverability, then a different hull design is called for. One of the most enjoyable characteristics of the tailboat is it's maneuverability, including the ability to go in forward or reverse directions and tucking in and out of inlets along the shoreline. Most kayaks don't like to turn. Unlike the Hobie Mirage, you never need to paddle the tailboat.

Sorry...but I can't divulge much about fin sizing or drive kinematics. Well, I could, but I'd have to shoot you. ;) There's a number of subtleties about how the propulsion fin operates due to the unsteady aerodynamic behavior of oscillating foils.

Regards,

Tom

I57

11-20-2010, 12:34 AM

chilihead98

11-20-2010, 12:51 AM

Tom
I have moved on to a faster better peddle boat and have been thinking of ways of using the hull of my original boat. It has been sitting in the backyard gathering dirt and leaves. The tailboat concept seems a good concept and would not take a lot to fit the drive.
The purpose of this forum is to share ideas and concepts, not to say I can't divulge things. If you are worried about people taking your ideas then why go on this forum?

Ian

Ian,

Most people on the BoatDesign website are engaged in the boating business, as am I. I'm here to keep my pulse on the pedal power industry.

Hobbyists commonly share their ideas openly with other hobbyists. Businessmen generally protect their intellectual property. I'm generally willing to provide qualitative information on how the boat operates. I hope this helps explain where I'm coming from.

Kind regards,

Tom

I57

11-20-2010, 02:05 AM

chilihead98

11-20-2010, 10:26 AM

Tom
I would say most people on the pedal boat forum are amateur enthusiasts like myself who design and build their own boats. It is a process of trial and error and by discussing your progress or lack of it the forum helps. I don’t have a problem with a business going on to keep their finger on the pulse. No doubt a lot of us amateurs who put our original ideas on the forum do so knowing others will be using those ideas.
Don’t worry, I will not be stealing any of your intellectual property or using it.

Ian

Ian,

The BoatDesign website is what it is. There are a lot of professional naval architects, engineers, and other marine industry professionals on it. And boats being a lot of fun to sail and build, there are also a lot of hobbyists. We're all free to use it as we wish. And, with luck, the dialogue and give & take benefits all of us.

I encourage people to ask questions. If you think you would get more info on fin propulsion out of Hobie, by all means, feel free to direct your questions to them. ;)

Kind regards,

Tom

zipboater

11-22-2010, 01:02 PM

I am developing a pedal drive concept which I hope to produce commercially.
By using some very old mechanical principals and modern materials I have created a propeller drive that yields almost six times the prop speed (at zero load) of the conventional technology. I am about three weeks away from completion of the prototype. There are a several advantages this drive will have, if it works. :idea:

spidennis

11-22-2010, 01:20 PM

NoEyeDeer

11-24-2010, 07:42 PM

Six times the prop speed at zero load is a meaningless statement on its own. For a start, the prop speed is simply a matter of gearing. You can get any prop speed you like. To be relevant you would have to include other information such as diameter, pitch, and what thrust it can produce when powered by the average human.

zipboater

11-29-2010, 11:16 AM

spidennis

11-29-2010, 11:37 AM

Keep us updated on your progress!

zipboater

11-29-2010, 11:46 AM

Thanks. I'll send pics asap.

portacruise

11-30-2010, 10:47 AM

The design I have doesn't use conventional gears. I haven't filed a provisional or regular patent application but I have dated and witnessed the prior art and a cursory search has not turned up any conflicting patents so far. Many inventors are paranoid of someone stealing their idea before they can "cash in". The fact is, it takes as much effort and money to steal and develop a patentable idea as it does to execute the process in an honest manner.

PROFIT MARGIN FOR PEDAL BOATS IS LOW OR NON EXISTENT, SO YOU ARE SAFE FROM SOMEONE STEALING YOUR IDEA. EVEN HOBIE FLIPPER DRIVES MAY NOT BE AT BREAK EVEN COMPARED TO THE REST OF THEIR BUSINESS, AS THEY SELL A LOT LESS OF THOSE THAN THE CLUNKY PADDLE WHEEL TYPE YOU SEE AT RESORTS.

IF THERE ARE GOOD PROFITS TO BE MADE FROM A PATENT, COPYCATS WILL APPEAR THAT WILL TWEAK THE ORIGINAL JUST ENOUGH SO IT CAN GO AROUND THE PATENT. ITS A GAME OF DEEP POCKETS AND ONLY THOSE WITH HUGE RESOURCES CAN AFFORD TO ENFORCE THEIR PATENT RIGHTS. EVEN THEN YOU HAVE COUNTERFEITS FROM CHINA WHICH WILL BE UNREACHABLE, IF THERE IS ANY PROFIT IN IT. A PATENT DOESN'T MEAN THE CONCEPT WORKS AT ALL, AND MOST EXPIRE WORTHLESS EVEN IF THEY WORK , TO SAY NOTING OF THOSE THE VANITY PATENTS WHICH SOMETIMES BANKRUPT WEALTHY BACKERS.

I am currently Frankensteining my drive system into a small monohull for testing. I am using an old 13'6" fiberglass AMF Dolphin sailing hull which I have pared down a little to reduce weight. The prototype drive unit is comprised of a 10:1 pedal drive which turns a small aluminum disc (the power take-off). This allows me to power two counter rotating shafts. I am starting with (2) 3-blade props, 7.75" x 12" pitch. To many of you experts out there, this is probably akin to powering a log with an egg beater.You're probably right. We'll see.
The power take off wheel is 1/4" thick marine aluminum. I am using urethane wheels affixed at (and tracking along) the perimeter edge on opposite sides of the power take off wheel to drive the 5/16" shafts. I am using belts and pulleys to deflect the shafts 9" to port and 9" to starboard.

FROM THESE FEW DETAILS, I AM GUESSING SOME KIND OF FRICTION DRIVE IS INVOLVED. THE LOSSES WOULD BE MUCH HIGHER THAN WITH GEARS OR CHAINS INVOLVED, NOT A WAY TO ACHIEVE RECORD SPEEDS OR EFFICIENCIES.

With this prototype I hope to have a cool fishing boat. If this works or shows promise, the next embodiment will be for the purpose of balancing utility and performance. My goal is to produce the second fastest pedal drive boat in the world. One advantage this design will have is that it will allow for a much shallower operating depth. I live in the Lousiana marsh lands so for me that's a necessity.

YOU GOT TO GO FOR IT, YOU MAY ON TO SOMETHING. DETERMINATION CAN OVERCOME STATISTICS....

HOPE THIS HELPS,

PORTA

zipboater

11-30-2010, 12:47 PM

Thanks for your insights Portacruise. You are correct about the patent issue. I have a couple of patents pending now on other inventions. There are millions of patents, relatively few successful ones. Getting a licensing agreement negotiated is another hurdle that can be a slippery slope. I know this from personal experience, but like my dear late dad used to say,"one sure way to never catch a fish is don't put your line in the water."
As for the friction drive, you nailed it. I am anticipating there will be some losses to minimize. I have designed a tensioner that will be self-adjusting, which I hope will help.
I look forward to sharing the results with you. I'll have more info in about two weeks.
Oh yes, before I log off. This unit, if successful, could be adapted to almost any hull. I am hoping to find a niche by offering custom built drive units which can be retrofitted to sit-on and sit-in kayaks, pontoons, or monohulls.

portacruise

11-30-2010, 11:44 PM

Oh yes, before I log off. This unit, if successful, could be adapted to almost any hull. I am hoping to find a niche by offering custom built drive units which can be retrofitted to sit-on and sit-in kayaks, pontoons, or monohulls.

This sounds like a good approach. Sometimes the bells and whistles or parts have greater financial success that the unit itself. Replacement powerboat props would seem to have a bigger margin than the power motors themselves, looking at what they cost. Some kayak paddles sell at outrageous prices. Maybe that's why they give computer printers away, knowing they can hit you on the cartridges, especially if they're non-refillable....

Porta

zipboater

12-01-2010, 05:19 PM

Every invention and innovation has its own unique inertia from original conception to fruition. Much like propogating and raising a child, many factors influence what the end results will be. Nothing trumps one studying and understanding as much of the process as one can before committing to a particular strategy for achievement. If anyone is pursuing a patent, be it a design, improvement, or utility patent I would recommend they learn what legal claims are and devise a way to describe their invention broadly enough that every possible embodiment of the thing is included in the scope of their claims, and narrowly enough that an entity desiring to make small changes for the purpose of circumventing the patent rights could be thwarted.(You probably won't get patent approval if your legal claims involve adding elements to claims that describe prior art)

portacruise

12-02-2010, 10:47 AM

My goal is to produce the second fastest pedal drive boat in the world. One advantage this design will have is that it will allow for a much shallower operating depth. I live in the Lousiana marsh lands so for me that's a necessity.

What about the "mud" motor design for those shallow depths? That's more or less what I use, and it works fairly well. Weeds, grass, tree limbs, fishing line and other stringy debris have been more trouble than dealing with the shallow depth. There are "weed free" props, prop cages, razor cutters, etc., but they don't work well when there is medium to heavy debris in my area (TX). Even folding props will be stalled by medium to long stretches of shallow or weedy water because no forward thrust occurs when they are in folded position. Jet boat drives seem to be about the best, but even their intakes can be gummed up if you slow down. Then you have to jump off to clear the intake. Hobie flippers and tailboat and paddlewheels arrangements will have their issues in shallow and/or weeded water. Guess that's why the paddle is still king, and maybe always will be...

Porta

zipboater

12-02-2010, 07:18 PM

What about the "mud" motor design for those shallow depths? That's more or less what I use, and it works fairly well. Weeds, grass, tree limbs, fishing line and other stringy debris have been more trouble than dealing with the shallow depth. There are "weed free" props, prop cages, razor cutters, etc., but they don't work well when there is medium to heavy debris in my area (TX). Even folding props will be stalled by medium to long stretches of shallow or weedy water because no forward thrust occurs when they are in folded position. Jet boat drives seem to be about the best, but even their intakes can be gummed up if you slow down. Then you have to jump off to clear the intake. Hobie flippers and tailboat and paddlewheels arrangements will have their issues in shallow and/or weeded water. Guess that's why the paddle is still king, and maybe always will be...

Porta

Hey Porta,
When you mention "mud" motor, are you talking about something akin to the Go Devil?

cutyourway

12-02-2010, 07:33 PM

I have a lot of experience with bike technology, and always wanted a high-performance pedal boat. I've witnessed/ ridden several designs, and so far have been thoroughly unimpressed. Pedaling allows maximum human power output, but what good is that if the vessel design is poor? That said, here are some guidelines to improve focus on vessel design:

Research
i. Check out what the velocycle hobbyists have been doing. The main difference between a velocycle and a veloboat is one is air-tight, while the other is water-tight. Most velocycle designs ignore low speed stability problems, as well as ingress/egress.
ii. That said, note the cyclist position is designed first;
iii. Then the chassis, including drivetrain & steering,
iv. Finally, the hull is designed and constructed, so cyclist and chassis are streamlined.
v. Google "human powered hydrofoil"

Workflow
1. Start collecting junk bikes. Even the dirtiest, rustiest bike is good for its chromoly tubing and pre-bent tubes. Plenty of people discard bikes after only a flat tire or maladjustment. Plus, Even if your project falls through or your collection gets wrecked, you can sell the whole lot for scrap.

1a. If you don't have the space for a collection, look for / start a local community bike shop. In my region, I know plenty about the assets of Denton, Dallas, Austin, New Orleans, and Denver community shops. They would love to help you build your boat!

2. Disassemble and sort all the bike parts. I have developed a method for this that will require a whole page itself, contact me if you want it.

3. Learn to weld. Within 10 hours practice, research, and instruction, you can make high-performance weldments that you can trust your life with.

4. Based on your knowledge base, shipwrighting ability, and collection of parts, start designing your craft.
4a. Don't have the parts you need? NOW you can go shopping. Be careful, you only need the most expensive bike parts to win bike races! Even the cheapest Chinese bicycle bearings can deliver fantastic efficiency when properly installed and maintained. And winning the Rat Race only requires your measurement of average speed, and knowledge of the Transportation Code and Judicial System. Imagine how much ass you could kick with your amphibious velocycle.

Since I want a ducted-propellor, I haven't even come close to getting this step complete. I don't know how to get a ducted propellor, much less which design is optimal. The easy way out for me would be a riverboat-style paddle-wheel design. It may be better anyhow, since it may allow operation in less than 15cm water, and could never get tangled or jammed.

spidennis

12-02-2010, 08:23 PM

In Austin, Tx, why would you need such shallow draft? Are you talking "Town Lake"?

MLampi

12-02-2010, 09:45 PM

...Hobie flippers and tailboat and paddlewheels arrangements will have their issues in shallow and/or weeded water. Guess that's why the paddle is still king, and maybe always will be...

Porta

In my experience with my paddle wheel driven canoe I found that paddle wheels are superior to paddles in very shallow water, and no worse in very weedy water.

The downside was the amount of water that wheels throw into the air when rotating rapidly and their additional weight and space requirements.

Michael Lampi

cutyourway

12-02-2010, 11:27 PM

For the shallow draft question, I was thinking I could cast the boat in more places, like in random creeks and very gradual beaches. Two things I hate about boating are running aground, and getting my feet wet. Nothing against water, it's just the point of having a boat is to stay dry, right?

Going back to paddle wheel design, It should be very easy using bike technology, and very cheap, allowing all paddlewheel problems to be addressed. For example:

1. Cavitation: by increasing the diameter of the wheel, the paddle motion approximates a straight line, the wheel hub can be mounted higher, allowing the paddle to vector water through <<60 degrees, instead of the typical 170 degrees. This alone, simplifies paddle design optimization, and reduces water throwing. 26" wheels are so popular you can find them lying in the street. So why use anything smaller? Furthermore, the paddles can be mounted radiating from the rim instead of the hub, increasing diameter to 50" or more.

One reason I want to stay away from propellors is because of wingtip turbulence, which can only be absolutely eliminated by ducting, which is difficult; or, through lots of hydrodynamic library research; I know that some doctors out there has done propeller/water tunnel experiments, but by the time I find that data I could already have built a dozen paddlewheels and had a lot more fun!

Paddles are easier to fabricate and field-observe than propellors, which means that scientific design adjustments are faster. Who needs documents when a hammer does the job?

2. Weight: Since a paddlewheel does not experience the kinds of shock loads as a road bike, and the assembly will probably be inboard, the cheapest, lightest wheels will work great. The (multi-speed) transmission is already designed, and is above the water line, so no shroud and seal are required; that saves a lot... So, let's do a weight estimate of the system:

TWO REAR WHEELS: 3 kg MAX
12 STAMPED ALUMINUM PADDLES, 24GAUGE: 2 kg MAX
EXTRA DRIVE CHAIN: .5 kg MAX
wheel mounting, using salvage bike forks: 1.5 kg MAX
TOTAL 7 kg MAX weight for the business end of paddle wheel drive system. Surely I can beat this weight estimate.

So how does this estimate compare to propellor designs? It is much more voluminous..
How

portacruise

12-03-2010, 02:04 AM

Hey Porta,
When you mention "mud" motor, are you talking about something akin to the Go Devil?

Yes, something along these lines, but with the capability as noted in the movies below:

http://www.boatdesign.net/forums/inboards/prop-shaft-systems-24636-4.html See post 53 and 54.

Porta

portacruise

12-03-2010, 02:11 AM

In Austin, Tx, why would you need such shallow draft? Are you talking "Town Lake"?

Naw, I'm a river rat. Craft something along these lines, but much lighter and smaller with the capability to go in under 6" of water for extended distances and pack to remote locations: http://www.prophish.com/pedalboats.html#features

P.

portacruise

12-03-2010, 02:20 AM

In my experience with my paddle wheel driven canoe I found that paddle wheels are superior to paddles in very shallow water, and no worse in very weedy water.

The downside was the amount of water that wheels throw into the air when rotating rapidly and their additional weight and space requirements.

Michael Lampi

Hi, Mike. How did you adjust the immersion depth so the wheels didn't hit rocks or the bottom in shallows? Maybe something like this can handle both weed and shallows, but seems slow and bulky http://www.youtube.com/watch?v=BIKZvFy6Elg

V.

Dave Gudeman

12-04-2010, 05:17 AM

This is probably going to sound a little wild, but for dealing with shallow water, why not design the paddle wheels to also act as wheels? I'm not talking about anything that could handle long distances --just enough to get up on a beach or to launch from a muddy bank without having to step in the mud.

I'm also not talking about tires with ridges. Those don't look like they are very efficient at water propulsion. You want to compromise on land propulsion, not water propulsion, so you want a good paddle wheel first.

I can think of several ways to do this. If the paddle wheel is a broad stern wheel with paddle boards held between two rims then you could put tires on the rims. The tires would stick out just an inch or two beyond the paddles. They would add a bit of weight, but I don't think it would make the boat less efficient otherwise.

Alternatively, if you have two side paddle wheels, then maybe something like a bicycle tire with the paddles sticking out the sides. Again, the presence of the tire shouldn't add any inefficiency beyond the additional weight.

There is another possibility for the side paddle wheels. I wonder how it would work if there were a thin tire over the whole wheel the same width as the paddles. In other words, the paddles would effectively be wide spokes in a wide wheel. This would probably reduce efficiency, but it might not be so bad. You could put a gap in the wheel at the leading edge of each paddle for water to flow off the end of the paddle as the paddle leaves the water.

You may need to have multiple gears in order to peddle both the paddle wheel and the wheel.

portacruise

12-04-2010, 01:31 PM

The efficient paddle wheels which I have seen would be compromised significantly if also acting as rolling wheels. Here's the hpb site which show various fast paddlewheels with a little browsing http://www.humanpoweredboats.com/Photos/UniversityDisplacementHPBs/UniversityDisplacementHPBs.htm
hydrodynamosaurs, clementine, etc. I like TUHHsneda because it works using water friction instead of having to fight this friction for speed. Generally paddlewheel systems have the disadvantages previously mentioned, plus a higher profile which introduces more wind resistance and being more prone to damage at shallow conditions than say a flex prop shaft. Wide tires would be the most versatile because they would handle difficult shallow water conditions like rocks or soft mud while having an easy time with hard pack or sandy bottoms. Here a clip showing what can happen when running over a rock in shallow water with the ideal wheel shape: http://www.youtube.com/watch?v=YxkXzjHsCx4&feature=related

Hope this helps.

P.

This is probably going to sound a little wild, but for dealing with shallow water, why not design the paddle wheels to also act as wheels? I'm not talking about anything that could handle long distances --just enough to get up on a beach or to launch from a muddy bank without having to step in the mud.

I'm also not talking about tires with ridges. Those don't look like they are very efficient at water propulsion. You want to compromise on land propulsion, not water propulsion, so you want a good paddle wheel first.

I can think of several ways to do this. If the paddle wheel is a broad stern wheel with paddle boards held between two rims then you could put tires on the rims. The tires would stick out just an inch or two beyond the paddles. They would add a bit of weight, but I don't think it would make the boat less efficient otherwise.

Alternatively, if you have two side paddle wheels, then maybe something like a bicycle tire with the paddles sticking out the sides. Again, the presence of the tire shouldn't add any inefficiency beyond the additional weight.

There is another possibility for the side paddle wheels. I wonder how it would work if there were a thin tire over the whole wheel the same width as the paddles. In other words, the paddles would effectively be wide spokes in a wide wheel. This would probably reduce efficiency, but it might not be so bad. You could put a gap in the wheel at the leading edge of each paddle for water to flow off the end of the paddle as the paddle leaves the water.

You may need to have multiple gears in order to peddle both the paddle wheel and the wheel.

MLampi

12-04-2010, 02:30 PM

The paddles on my canoe's paddle wheels extended only about 5 or 6 inches into the water. There were enough blades around the 27" bicycle rim that when I did accidentally encounter a sand bar on one side it merely lifted the canoe up and over the bar.

There was for a couple of years a company in Port Townsend, WA that sold copies of their amphibious side wheeler canoe. They used standard bike wheels with blades near the rim for water propulsion and tires for hard surface propulsion.

I think there are some photos on the www.humanpoweredboats.com web site.

Michael Lampi

cutyourway

12-07-2010, 01:33 AM

Yes I agree and am passively developing such a system. I have most of the parts, so I just need a little bit more space, vision, and motivation.

The idea of putting tires on the paddle wheel is great except for a few problems I can think of:

I want my paddles to radiate FROM the rim, to maximize paddle radius and further approach linear motion. If I am to maintain this design feature, then the tires and paddles must independently retract.
The surface area of the tire will generate bouyant force, and parasitic drag. These forces may be negligible for an innovative craft, and I'm imagining that this craft should hydrofoil as much as possible... In this case, maybe tires are a great feature, since dirtbikers and ATV'ers have mastered hydroplaning!
Any high-quality tire besides 20" can get pricey. Any 26" tire worth mounting starts at $30, where my favorite 20" is only $15.

This is probably going to sound a little wild, but for dealing with shallow water, why not design the paddle wheels to also act as wheels? I'm not talking about anything that could handle long distances --just enough to get up on a beach or to launch from a muddy bank without having to step in the mud.

I'm also not talking about tires with ridges. Those don't look like they are very efficient at water propulsion. You want to compromise on land propulsion, not water propulsion, so you want a good paddle wheel first.

I can think of several ways to do this. If the paddle wheel is a broad stern wheel with paddle boards held between two rims then you could put tires on the rims. The tires would stick out just an inch or two beyond the paddles. They would add a bit of weight, but I don't think it would make the boat less efficient otherwise.

Alternatively, if you have two side paddle wheels, then maybe something like a bicycle tire with the paddles sticking out the sides. Again, the presence of the tire shouldn't add any inefficiency beyond the additional weight.

There is another possibility for the side paddle wheels. I wonder how it would work if there were a thin tire over the whole wheel the same width as the paddles. In other words, the paddles would effectively be wide spokes in a wide wheel. This would probably reduce efficiency, but it might not be so bad. You could put a gap in the wheel at the leading edge of each paddle for water to flow off the end of the paddle as the paddle leaves the water.

You may need to have multiple gears in order to peddle both the paddle wheel and the wheel.

Clemens

12-16-2010, 11:45 AM

Hello TT,
finally finished my summer project. The new platform is attached to the garage's ceiling, ready for future expeditions.

My goals:

to reduce weight
to reduce number of parts
to enlarge area of platform for bigger tent

It took a lot of effort, though.
I worked with foam, with carbon and glass fibers and with epoxy resin.

Dimensions of the new platform:
2,40 x 1,60 x 0.12 meters, the front beams protruding another 0.6 meters.

Best greetings,
Clem

spidennis

12-16-2010, 11:56 AM

Very nice Clem!

What kind of trips and performance have you got going?
I'm thinking about using a similar system on my Ultimate Florida Challenge boat and can't wait to start trying this all out. got more pics? What drive are you using?

I wonder how this system would work out mounted off the back cross spar/beam, facing backward, peddling backwards? I don't have a lot of room and that would keep the "human powered outboard" out of the way as best as possible.

Clemens

12-16-2010, 12:23 PM

Hi Spidennis,
I'm planning further multi day excursions on the french canals, on Lake Konstanz, in the lake district "Müritz" in Germany.
Floats, yokes, drive units and rudder are original seacycle parts.
Cruising speed is roughly 6-8 km per hour, once I covered a distance of 45 km in one day.
Best greetings
Clem

Tiny Turnip

01-18-2011, 02:54 PM

Hi Clem - its looking good!
I still haven't slept out on my boat, but as soon as it gets warmer, we're going to give it a go!

zipboater

01-18-2011, 06:35 PM

i am about two more weeks from having my new drive concept ready to test. I will be posting a video of the results(with gps speed data) on youtube. so far so good. i think you guys are about to see a new way to haul ass on the water. i'm like a kid with a new toy. the weather has been a factor in finishing this project. I'm building this thing in my back yard. My carport is alreadyt full and I'm juggling a lot of other plates. Portacruise, things are looking good for the 2013 race season.

I57

03-01-2011, 03:16 AM

This forum has been quiet for a while, thought I might put in my news. My stabilised monohull has been undergoing constant changes. I have removed the dipping rudders and replaced them with a rudder. I use a small 100mm x 100mm one for at the lake where I have more room to move, and a larger one for on the river where I need to turn quicker. Have put in a straight 16mm aluminium shaft, angled at 16deg. and tried a couple of different props. Even snapped off a blade when doing a speed run, came back with a one bladed prop. It was a home made fibreglass prop, and is the first one to break. Have a four blade prop, the first time the cord was to narrow and spun too fast so beefed it up and could hardly turn it. Now have trimmed it back so should be ok, one advatage of a fibreglass prop you can reshape and resize easily. Have lowered the gearbox and made a cutout on each side of the hull for my feet. This has enabled me to lower the gearbox and seat by 100mm and the shaft angle has improved to 11deg. See how it goes when I finish the work on it.

Ian

Dennis A

03-05-2011, 05:38 AM

Hi Ian
I had a similar problem of over revving due to prop slip of up to 30%. To cure the problem I doubled the cord width but then struggled to turn the prop on the faster runs. My boat is very similar to yours and had a max sprint speed of 11.2 kph.
How much are you proposing to trim back the prop.

Did you take any action on the tilting prop idea.

Dennis

I57

03-05-2011, 06:46 AM

Dennis
The four blade prop was 20mm cord with a 400mm dia, this was much to light so beefed it up to 40mm cord and could hardly turn it. Have now made the cord 30mm but have yet to try it out. Have just finished modifying the boat whereby I have lowered the gearbox by making cutouts in the hull for my feet. The shaft angle has improved to 11 deg. and have also moved the outriggers further aft. Hope to get it on the water next week to see how it goes.
I managed to get to 12.5 kph with a two bladed prop before I broke it. Tried out one of Ricks folding props and flex shaft last week and got to 13.7kph. See how it goes with the better shaft angle and using a rigid shaft. I couldn't find any details on the tilting prop, an interesting idea.

Ian

Dennis A

03-07-2011, 03:31 PM

Hi Ian
Here is a simple sketch of the swiveling prop design. The only one I know of was 2 bladed with prop from bronze and shaft from steel, but I understand that this system is used on 2 bladed helicopters.
It uses the same princples to ensure that the prop is verticle as Ricks curved shafts.
I have not tried itas I find the use of a folding prop & a curved shaft is unbeatable.

Dennis

I57

03-08-2011, 01:43 AM

Dennis
Looks like the swiveling prop works in the same way as a universal joint. The fixing pin would have to be fairly strong as it would have a large shearing force acting on it. On my first boat I used a universal joint to get the prop vertical and managed to break a couple of them. The larger the angle of the shaft the greater the load and the bigger the pin. I had a 11 deg angle on the shaft and it was not a smooth action, could feel the joint clunking around.
Making the hub could be difficult as each end would have to be a cone shaped hole angled to the same angle as the shaft. Alternatley a tube with an internal ring which the prop would rotate around, this would be easier to make but would it work as well?

Ian

Jeremy Harris

03-08-2011, 04:12 AM

I have used a double universal joint to turn a propeller shaft through a large angle (80 degrees) quite successfully. The joints do need to be massively de-rated as the angle increases, though. For example, at 45 degrees the joint can only withstand 0.25 of the torque that it will operate at when at 10 degrees. The joint I used was made by Lenze (see here: http://www.techdrives.co.uk/html/universal_joints.html) and although I used the plain steel version I believe they do make a stainless one. The double universal has the advantage of being constant velocity at both ends, so gives smooth drive with no pulsing. I have found that a 10mm bore double joint running through 80 degrees and driving a 320mm diameter two blade prop seems to work OK, although I am running at higher rpm than your pedal application (up to 680 rpm maximum) so the torque is lower.

Jeremy

zipboater

03-09-2011, 10:23 AM

You have a beautiful boat. What sort of cruising speed you achieving? I have been getting delayed by weather and the obligation of my day job but I am still plugging away at getting my boat to tests as quickly as I can. I was interested in your fiberglass prop. I am looking for innovative prop manufacture ideas. I want to experiment with pvc. I have currently outfitted my boat with twin aluminum props. Counter-rotating 7.75in. two bladed. Who knows what the pitch is? but they are symetrical and balanced well enough. I'll get it to the lake someday. Glad to see your success. It's a beautiful craft you have .This forum has been quiet for a while, thought I might put in my news. My stabilised monohull has been undergoing constant changes. I have removed the dipping rudders and replaced them with a rudder. I use a small 100mm x 100mm one for at the lake where I have more room to move, and a larger one for on the river where I need to turn quicker. Have put in a straight 16mm aluminium shaft, angled at 16deg. and tried a couple of different props. Even snapped off a blade when doing a speed run, came back with a one bladed prop. It was a home made fibreglass prop, and is the first one to break. Have a four blade prop, the first time the cord was to narrow and spun too fast so beefed it up and could hardly turn it. Now have trimmed it back so should be ok, one advatage of a fibreglass prop you can reshape and resize easily. Have lowered the gearbox and made a cutout on each side of the hull for my feet. This has enabled me to lower the gearbox and seat by 100mm and the shaft angle has improved to 11deg. See how it goes when I finish the work on it.

Ian

I57

03-10-2011, 05:40 AM

Had the boat out today using the 4 blade prop with the cord width at 30mm, still felt heavy. If I was riding a bike I would have dropped a gear or two. 20mm was too light so might trim it to 25mm and see what happens.
Zipboater - My props are made of fibreglass around a square steel hub, the end of the shaft has a matching steel square rod. I use a piece of wire to stop the prop sliding off, easy to change over props. I glue a piece of ply around the tube and cut an angled slot for the thin aluminium sheet. This is cut to shape and curved, I then twist the sheets to the correct angles and then lay a sheet of fibreglass along one side. When this has hardened and I have the angles right I lay the rest of the fibreglass then sand and paint it.
My cruising speed is about 8kph, this speed I could maintain for an hour or so depending on how my back holds up.

Ian

I57

03-17-2011, 01:54 AM

Have recently fitted a flex shaft and folding prop to the boat, courtesy of Rick. Then had the idea if a flex shaft can go up and down to avoid snags why not go from side to side to steer the boat. The flex shaft has a aluminium strut near the prop which slides in a slot in the steering arm. The arm is harder to move than a rudder so needs a bit more leverage. It works, tried it out today for the first time and turned better than with the rudder.
The flex shaft is at an angle of 11deg. the shaft has a shallow curve with a
flex section of 1.3m. The extra load when turning loads up the shaft a lot more so the steering arm needs to be quite solid.

Ian

portacruise

03-17-2011, 09:52 AM

Yes, there are certain situations where a rudder is not very responsive and this would be about the only way to turn. Like when going with the flow below the rapids on a river. You don't have the luxury of lag time when you want to avoid an overhanging branch or boulder in the middle of the stream. The flex shaft also allows travel in very shallow water as it swings up and around when hitting rocks or the bottom. http://www.boatdesign.net/forums/inboards/prop-shaft-systems-24636-4.html post 54 and 53.

P.

Have recently fitted a flex shaft and folding prop to the boat, courtesy of Rick. Then had the idea if a flex shaft can go up and down to avoid snags why not go from side to side to steer the boat. The flex shaft has a aluminium strut near the prop which slides in a slot in the steering arm. The arm is harder to move than a rudder so needs a bit more leverage. It works, tried it out today for the first time and turned better than with the rudder.
The flex shaft is at an angle of 11deg. the shaft has a shallow curve with a
flex section of 1.3m. The extra load when turning loads up the shaft a lot more so the steering arm needs to be quite solid.

Ian

MLampi

03-20-2011, 04:41 PM

Hi, Mike. How did you adjust the immersion depth so the wheels didn't hit rocks or the bottom in shallows? Maybe something like this can handle both weed and shallows, but seems slow and bulky http://www.youtube.com/watch?v=BIKZvFy6Elg

V.

Sorry...been away from this site for a while building a new boat, etc.

No, the paddles were set up so only the 6" vanes were immersed in water. The vanes were mounted on the would-be tire edges of 27" bike rims, and were strong enough to lift the canoe to which they were mounted out of the water if necessary.

I traveled up streams with as little as 2 or 3 inches of water, and tidal areas choked with weeds. I never worried about rocks, weeds, shallows, etc.

Michael Lampi

MLampi

03-20-2011, 04:55 PM

I57

03-21-2011, 01:46 AM

Mike
It is one of Rick's folding props so when I hit shallow water the blades fold and the shaft bends up, the strut slides up its slot. On one of my earlier setups I had a vertical post near the stern with a cord attached to the top of the strut ( see post #979 on this thread). This worked to a point but the cord would sometimes jam and I had to wind up the cord and stow it. Where I go I am into deep enough water close to shore. It means carrying the boat a few metres but getting wet is not a problem where I live even in the winter.

Ian

JTA

03-26-2011, 10:58 AM

Ian

Please bear with me as I'm a total newby to this stuff but I find it extremely interesting and looking forward to finding a new way to get some exercise.

After doing quite a bit of reading through these forums lately, particulary some of Rick W's from past years, I was wondering if I could get some addtional info. I came accross the post from Rick listing all the details about his boat (gear box, prop, etc) but I would like to know more about the flexible shaft (where to get it and how long it should be). Also, some of the links of where to get the prop where old so maybe you can suggest a place to get these also.

Any details/specifics (pictures) would be helpfull.

Thanks
John

I57

03-27-2011, 07:22 AM

JTA
Sizing a flexible shaft is beyond my technical ability, if you log into the
hpv boats website http://www.mail-archive.com/hpv-boats@bikelist.org/maillist.html . Someone on there can give you the details you are after.
The first step is to work out what sort of drive you are going to use. There is the twisted chain drive or a 90 deg gearbox. Depending upon the gearing will determine the prop size. For example my first boat had a bike chain turning a gearbox, the total gearing was 1:8. That is every turn of the crank turned the prop 8 times, the prop had a diameter of 250mm. My current setup is a 1:3 gearbox with the cranks fitted and the shaft running directly off the gearbox, prop size is 430mm diameter. The flexible shaft is 8mm spring steel, the tighter the curve the more strain and shorter lifespan. I make my own props out of fibreglass and use a program called Java Prop to size them.
With my latest boat I have fitted one of Ricks folding props which has steel blades. Are you building a boat or converting one? If you post some details I might be able to give you a hand. It involves the hull size(beam & length) and total load on the boat. What sort of speed you want and what conditions the boat is used (lake, river, bay). Hope all this waffle helps.

Ian

portacruise

03-27-2011, 04:13 PM

Awhile back, I did a lot of searching for the SPRING steel flex shaft in the larger diameters that Rick and Ian use and was not able to find a supplier in the USA. The flex part does not have to run the entire length if it will run through a support skeg as in Ian's design, the front portion can be rigid aluminum. The closest thing I have found that is available at just about any hardware (home depot, Lowes) store is 1/4" (6.3mm) electricians drills or extensions.

http://www.toolsofthetrade.net/industry-news.asp?sectionID=1490&articleID=1498824

I use 3/16" in my applications which are not human power related and they are way more than enough for my application. There are claims that 3mm diameter spring has enough torsional strength to handle the 250 watt human output, but like Rick, I doubt that 3mm would stand up to shock load and necessary stiffness. Using a magnetic pedal crank gearbox as Rick has developed would solve the shock load issue. But then the torsional compliance one remains with thinner diameter spring steel shaft, maybe can be minimized with shorter lengths of the flex section.

The easiest and cheapest way to go on the props for human power is to use 16X16 APC model airplane props, though this may require tall up gearing depending on how much power you are capable of for pedalling. http://www.amainhobbies.com/product_info.php/cPath/3_1577_755_756/products_id/36392/n/APC-16x16-140-Pattern-Propeller

Hope this helps.

Porta

Ian

Please bear with me as I'm a total newby to this stuff but I find it extremely interesting and looking forward to finding a new way to get some exercise.

After doing quite a bit of reading through these forums lately, particulary some of Rick W's from past years, I was wondering if I could get some addtional info. I came accross the post from Rick listing all the details about his boat (gear box, prop, etc) but I would like to know more about the flexible shaft (where to get it and how long it should be). Also, some of the links of where to get the prop where old so maybe you can suggest a place to get these also.

Any details/specifics (pictures) would be helpfull.

Thanks
John

JTA

03-27-2011, 07:17 PM

Ian/Porta

Thanks for the input. I guess my initial thought was to follow what Rick W described here (http://www.boatdesign.net/forums/boat-design/converting-bicylce-pedal-boat-25486.html post #5). Using a bike crank connected to a Mitrpak 2:1 gear box thereby getting the 1:8 ratio, using the flex shaft described attached to a model air prop as described and shown in his photo. As far as the hull goes I'm still unsure but I think I would be leaning towards a sleek/thin catamaran design somewhere in the 12'-14' range. I know a monohull with stabilizers would be faster but I'm more concerned with stability and I thought with the cat option I could sit a little higher above the water (reducing spray). Again, the main purpose would be exercise, not racing. I would be using the boat in a coastal bay and back area canals/creeks. As far as load goes, well that's why I need it, the passenger load will be in the 225lb range, as for the hull/hulls (cat) I'm not too sure. I did a little research on stitch & glue technique and feel I could probably do something like that. Another thought I had, not sure if it would work, was to use some flotation foam billets to carve them into a shape of the hull and then glass over them. Again, not sure if you could glass directly to the foam or if you need to cover in wood first. Any thoughts/insights?

Thanks
John

I57

03-28-2011, 12:10 AM

JTA aka John
Using a foam block and glassing over I reckon is the hardest and heaviest method of construction. Shaping the foam block is messy, all that foam shaving floating in the air and hard to clean up. After glassing over you have to coat it with gelcoat or some other sealant as fibreglass on its own is porous. No matter how well you seal it over time water does seep in and is absorbed by the foam, the water can't drain out and the boat just gets heavier. I'm probaly ranting a bit but I built a surfski like this once and it was a flop right from the start.
My current boat I built using 3mm plywood with internal framing every 200mm and internal fibreglass strips along the joins. It is a basic box construction but easy to make, the flat sides and bottom are ok for this type of hull. I sealed along the join on the outside and gave it three coats of paint. The result is a reasonably light strong hull.

Ian

Submarine Tom

03-28-2011, 01:45 AM

Ian, I'm sorry your fiberglas experience was bad.

John, I would recommend fiberglas or fiber/epoxy, especially for a cat. You can make one mold and then lay-up two hulls. Brace them internally and shazam! You don't have to make a mold, you can lay-up on braced veneer, you'd have every success. You'll get a terrific strength to weight ratio.

-Tom

zipboater

03-28-2011, 02:41 PM

Ian thank you for the input about your prop fabrication. I have been dry running the drive system in my boat. It consists of a 10:1 direct drive pedal and sprocket which turns a 12.5" diameter, 1/4" thick aluminum disc. I use two 4" diameter non-skid industrial grade caster wheels fastened by a tensioner that induces each wheel to travel along opposing sides of the main aluminum disc. The caster wheels are each coupled to a pulley at both port and starboard sides of the main drive disc. I have this drive set up to yield about a 27.5:1 prop to pedal ratio. This configuration allows me to drive multiple props. In this boat I am running dual props. It also has given me the option of running much smaller diameter props and thus, has made it possible to reduce the minimum operating depth. I am about three months behind my projected finish date. Oh well, onward through the fog! Good luck to you.

JTA

03-28-2011, 08:24 PM

Ian/Tom

Thanks for the responses.

Ian:
Is that the Hull from the pictures in your above post (#1053) that you are using the Flex shaft attached to your steering rudder arm? This is something I think I could tackle. So if I made two identical hulls (say 12' long) in a similar design/construction to what you are describing, would a bike crank to a gear box giving a ratio of 1:8 be sufficient to push the boat for exercise puposes? Again, I'm still unsure about the Flex shaft part (where to get), is it nothing more than what Porta described above (electricians flex drill attachment) or is this something that Rick W. has designed/produced for private use? I saw one of your earlier posts that shows your boat with the shaft (solid shaft) coming through the bottom of the hull. If I build the cat version and have a straight solid shaft coming down between the 2 hulls, I assume I would need a prop with a special pitch to compensate for the angle of the shaft right. I see you make your own props but that is beyond my abilities. This is why I was leaning towards the Flex shaft (if I could locate one) as it seems it comes right out of the gear box into the water, correct?

Tom:

Thanks but I don't think that I would be capable of doing a mold but I guess the Lay-up on braced veneer would be similar to glassing over a frame like Ian has shown, right? If you did this application, how many layers of fiberglass cloth would you need to use?

Thanks to all;
John

Submarine Tom

03-28-2011, 09:49 PM

John,

That depends. I would consider epoxying two or three veneers (on braces, so curved) together and then a couple of 16 oz cloth layers on top (exterior). That may even be over-kill, because you're running a cat there will be no point loading in your hulls. Any chance you could get a couple of used rowing shells cheap?

-Tom

portacruise

03-29-2011, 12:24 AM

Rick indicated in a post (somewhere on the archives of this list) that an electrician's drill shaft (I assume 1/4") was used at one point in Greg K. record breaking 24 hour boat. This was an endurance record, so probably no problems with low shock load due low, steady cadence....
http://en.wikipedia.org/wiki/Greg_Kolodziejzyk
This was because nothing else could be found in Canada in the larger diameters on quick notice. The flex shaft was run without a strut in that boat to get better efficiency... I think the 1/4" electrician's extension will work for what you have in mind especially it won't have much of a curve in it, unless you will be sprinting a lot. You can reduce the curve by using a stiff upper section of aluminum tube and shorter section of flex or even control the curve with skeg position to a degree. Besides, even if it breaks, you only lose a short section of shaft and cheap prop. You can carry a spare of each on board that quickly slips in for replacement. I use a quick release hex connector in my setup and this is replaced in a few seconds. Losing a homemade prop would be different as this would be a great loss of many hours of delicate, time consuming labor.

As regards your post above on converting a bike to a pedal boat, the prop in your attached picture from Rick is not a model air prop, but one of Rick's homemade ones, from what I can make out... Yes, the 2 look amazingly alike in general shape...

Unless you are racing or trying to set records of some sorts, I don't think a custom made prop is necessary regardless of configuration. At least one successful commercial version of a human pedal unit by Bob Stuart used the APC 16X16..

The flex can be configured to come straight out of the gear box and into the water as pictured in Ricks post, and is even easier to do with a cat.

P.

Ian/Tom

Thanks for the responses.

Ian:
Is that the Hull from the pictures in your above post (#1053) that you are using the Flex shaft attached to your steering rudder arm? This is something I think I could tackle. So if I made two identical hulls (say 12' long) in a similar design/construction to what you are describing, would a bike crank to a gear box giving a ratio of 1:8 be sufficient to push the boat for exercise puposes? Again, I'm still unsure about the Flex shaft part (where to get), is it nothing more than what Porta described above (electricians flex drill attachment) or is this something that Rick W. has designed/produced for private use? I saw one of your earlier posts that shows your boat with the shaft (solid shaft) coming through the bottom of the hull. If I build the cat version and have a straight solid shaft coming down between the 2 hulls, I assume I would need a prop with a special pitch to compensate for the angle of the shaft right. I see you make your own props but that is beyond my abilities. This is why I was leaning towards the Flex shaft (if I could locate one) as it seems it comes right out of the gear box into the water, correct?

Tom:

Thanks but I don't think that I would be capable of doing a mold but I guess the Lay-up on braced veneer would be similar to glassing over a frame like Ian has shown, right? If you did this application, how many layers of fiberglass cloth would you need to use?

Thanks to all;
John

I57

03-29-2011, 05:25 AM

John
The hull I made has the shaft going through it. This was to suit the gearbox I have, the shaft comes directly from the gearbox to the prop. It is a very simple setup, gearbox - shaft - prop. The less parts and bits the better, Ricks V14 uses a bike chain driving a 1:1 gearbox with the shaft running down the side of the boat. Your setup will be dictated by your drive/gearbox setup, the 1:8 ratio with correctly sized prop will have no problem pushing the boat. Get a strong sturdy gearbox as with a small one you can strip the gears ( I'm speaking from experience). The key is the right prop size, too small and you will spin like crazy and get nowhere. Too big and its like trying to ride up hill in top gear.
My boat has a solid section of 16mm aluminium rod 2m long that runs through the hull and is fixed to a 8mm spring steel flexible shaft 1.3m long.
You can use plain steel rod or 10mm aluminium rod for the flexible shaft as long as the curve is shallow (6m - 7m radius). The cat layout will make it easier to setup your drive and seat. It makes raising the flex shaft out of the water easier and also if want to steer using the flex shaft.
With your boat size try and make it as long as you can. The constraint will be transport/storage. How will you get it to the water? With my boat I transport it on the car roofracks, and then assemble it next to the water.
I have since learned that a shaft on an angle puts a large load on the prop and gets a lot of vibration plus loss in efficiency. The flex shaft allows the prop to spin vertically at its most efficient.
I did a quick rough calc. and two hulls 4m long with a beam of 250mm would draw about 100mm of water. How much freeboard would be determined by where you are using the boat.

Ian

I57

03-29-2011, 05:32 AM

Zipboater
Your props would have a terrific speed, 1:27.5 ratio. Thats about 1900rpm for a 70rpm cadence. Could you post a pic on this forum, would be great to have a look at it. These things always take longer than you think, my rule of thumb is estimate a time and then multiply by 4. Good luck.

Ian

JTA

03-29-2011, 08:02 PM

Thanks to all for your input.

Attached link (http://www.mitrpak.com/product_datasheet.php?product_id=31) is what Rick had posted in one of the earlier threads. So I understand that on one side of the gear box I would need to attach a sprocket to the shaft in order to attach the chain coming from the bike crank (I assume this is done by wedling the sprocket to the shaft ???). Can someone describe (pictures helpfull) of how you would connect the other shaft of the gear box to the shaft holding the prop (be it flex or solid)? Then, how does the prop get attached to the shaft?

Ian; as for the size of the hulls. I don't have a transport problem as I live on the water so if bigger is better (more stable/faster) then bigger they will be. Can you recommend an "ideal" size (legnth/width/hieght of the hulls and the spread in between) for my application (inland bays/canals: 225lb passenger load: water depth not an issue). Again, my off the cuff thought for the hulls was 12' long by 1' wide by 1.5' high seperated by 4' in between. Am I way off here?

Thanks Again
John

mike_sayer

03-30-2011, 04:22 AM

Hi all,

Just came across this excellent forum, and thought you might be interested in a project I'm running together with my friend Mark. We've designed, and are about to have built, a trans-Atlantic pedal-boat, which at the end of this year we're going to attempt to pedal across the Atlantic Ocean to raise £250,000 for two charities and hopefully set a new World Record. You can check it out on our website at www.torpedalo.com (http://www.torpedalo.com), and follow us on Twitter (www.twitter.com/torpedalo (http://twitter.com/torpedalo)) and Facebook (www.facebook.com/torpedalo (http://www.facebook.com/torpedalo)). I'd be delighted to answer any question you have about the design, construction and operation of the boat or drivetrain.

Thanks, all the best

Mike

I57

03-30-2011, 07:17 AM

You guys have your work cut out, 248 days to build the boat. Then fit it out and test it. Good luck!

Ian

mike_sayer

03-30-2011, 07:53 AM

You're not wrong. The whole build is being done for £0, through two main sponsors. As they're working for free, we can't demand priority over paying customers. Nevertheless, a timing plan is in place which will see the boat in the water by the end of July. Only gives us two months for testing, as opposed to the originally planned five, but if it was easy it wouldn't be as fun!

I57

03-31-2011, 03:45 AM

John
On my first boat I used a bike crank with a chain turning the gearbox. The sprocket I got from the bike shop was a problem fitting to the gearbox. I modified a few washers and bolted it on. Fixing the shaft depends on the gearbox, you could file a flat piece on the gearbox shaft and use a grub screw. I use a piece of tube between the gearbox and drill a hole at each end for a bolt. With the propeller I have been using a square rod fixed to the end of the shaft. The prop is made around a square tube, a piece of wire through the end of the square rod stops the prop from falling off. Another way is filing a flat piece on the shaft and fix the prop with a grub screw through the prop hub.
The size of hull you have shown will work but go up to 6m (18ft-19ft).
Over this length it can get hard to manouver, gives you that extra carrying capacity if you decide to do any extended trips and have to carry food etc.
Have a look at the Open waterbike website, lots of info there.
http://www.openwaterbike.com/

Ian

JTA

03-31-2011, 07:29 PM

Ian

Thanks for the info above. I started doing some hunting for supplies and I came accross some right angle gear boxes that had ratings of 5:1 all the way up to 60:1. Now these were referred to as speed reducers, meaning they were designed to have you connect some type of motor to the input side (higher number) and the output side shaft speed gets reduced down to 1, right? So can you use this in reverse, meaning connect the chain from the bike crank to the shaft on the 1 side and have the output side the larger side (higher rpm) going to your prop? Is this doing something different than the Mitrpak 2:1 described by Rick? Will the RPM's be too high for the prop? Will the crank be impossible to turn? Would this not give you additional speed?

See attached link and let me know what you think.
http://www.surpluscenter.com/sort.asp?catname=powerTrans&keyword=PGRSescribed

Thanks
John

I57

03-31-2011, 07:54 PM

John
Had a look at the website, looks like they may be worm gears from the way the shafts were positioned. If they are worm gears they won't work in reverse, its that type of gear. The mitrepak gears are spiral or bevel gears and are designed to work both ways. Better to spend a little extra on a robust gearbox that will do the job.

Ian

JTA

04-02-2011, 02:41 PM

Ian

Yes, you were correct, they were worm gears. I did not know the difference. Can't say that I was not trying to save a little $$ when I stumbled accross them (who doesn't like a deal), but the other reason that they caught my attention was the higher ratio's offered (just figured if 2:1 is good, 10:1 must be better) would yield higher RPM's at the prop. So I guess I will take your advice and go with the Mitrpak. Just one question, the setup you have, pedal crank directly into gear box, is that your own creation/fabrication or is it available commercially anywhere on the internet. I guess eliminating the chain is a plus (KISS) but do you loose any prop speed, are you still able to achieve 8:1 ratio (as Rick described) from pedal to prop?

Thanks
John

I57

04-03-2011, 04:58 AM

John
The gear ratio of 8:1 is not the only one you can use. Any ratio will work as long as the prop is correctly sized. A 2:1 gearbox directly connected to the prop will work but you will need a prop size of about 500mm dia. The slower the speed and larger the prop the more strain is placed on the gearbox. If you can get hold of a 4:1 gearbox it would be all you need, no chains. I use a 3:1 gearbox with a 430mm dia prop, the cranks are fitted to the gearbox. It was made by Involute but I don't know if they are still available, it is heavy but very strong and will last. The cost of a good heavy duty gearbox is about the same as a cheap mountain bike.

Ian

JTA

04-03-2011, 01:57 PM

Ian

Can you explain the calculation to me for the relationship between gear ratio and prop size? So in your previous post you say if you are using 2:1 (say at a 60 cadence) generating 120 RPM at prop you can use a 500mm dia prop. Or if you are getting 3:1 (again lets say at a 60 cadence) generating 180 rpm at the prop you could use a 430mm dia prop. I assume with all other things being equal (boat size/weight/length and rider) the resulting speed would be the same???

In addition to explaining the calculation can you explain at what point the legs can't take it? So for example in the above, if you are getting 3:1 as in your case, is there no benefit (increased speed) by having a larger prop (500mm) and/or is it the resistance is too much for the legs?

So in the end I want to know what will give the most effecient outcome for speed and comfort to the rider. You recommend above if I can find a 4:1 gearbox I would not need any chains. But I have been unable to find anything greater than a 2:1 (Mitrpak) that is not a Worm Gear.

So if I was to use the 2:1 gearbox and some combination of sprockets that could offer between 2:1 up to 4:1, how could I determine the "BEST" prop size for speed and rider compfort?

Thanks
John

I57

04-04-2011, 04:50 AM

John
I have a set of instructions for making a prop out of a piece of steel flat bar, approx. 30mm wide x 3mm thick. If you can make your own prop I can give you the size and angles. First step is to go ahead and make your drive unit, a mitrepak gearbox at 2:1 ratio and a bike crank and pedals. Make it as one unit with the gearbox as close to the crank as you can get it, this will keep the chain length to a minimum. When it is made you can get the exact gear ratio between the crank and the drive shaft. I can then work out using Java Prop the size of prop required, it is worked out by the cadence and the power. The program works out the width and angles of the prop, you put in the revs and the power. If you have a cadence of 60 rpm this equals 480rpm at the shaft for a 8:1 ratio, for a 4:1 ratio the shaft is spinning at 240rpm. The thrust generated by the props of different sizes is the same, a large slow turning one or a small faster turning one. It is the same principle as force by distance, the same amount of work is done. The higher the prop revs means a smaller dia prop, just as lower revs give you a larger prop. I have a chart for power levels for people of varying degrees of fitness and duration. Sizing the prop is like getting the right gear to ride in on a bike, only difference is there are no hills so you only need one gear.
If you buy a prop you have to size the drive to suit which is a bit like putting the cart before the horse. Can make it difficult getting the right gearing.
If you want the prop making instructions I can email them to you.

PS. You could use the Mitrepak gearbox in the same way I have shown on my last post. I could size a prop to suit, you would have to check if bike cranks can be fitted to the gearbox.

Ian

Submarine Tom

04-04-2011, 12:23 PM

Excellent post Ian. If I may add one thing John, the larger the prop the more efficient, generally speaking.

-Tom

JTA

04-04-2011, 08:58 PM

Ian

Thanks for the very detailed explanation that even I could understand. As for making my own props, I think it is probably beyond my skills (especially if it requires welding) but I would be interested in reading/learning how it's done. If you don't mind sharing your instructions my e-mail is jennacourt@yahoo.com.

So I did a little test on my recumbant bike in the basement for the first time this year. With no exercise in months and after a long cold winter of over eating I found I was able to keep an average/comfortable pace of 75-80 RPM; generating approximately the same Watts (75-80). When I increased the resistance and maintained the same cadence (75-80 rpm) I was generating approx. 100 Watts but I don't think I could maintain that level for a prolonged period of time (at least not until I build up some endurance).

I spoke to a guy at Mitrpak today who actually worked with Rick and Greg who was very helpful. Although they could special orderl/manufacture a 2:1 gearbox that would accept the bike cranks directly into the box (eliminating chain) the price was nearly double that of a conventional right angle box. Being my first endeavor, I think I will go with the less expensive option. Although I did not order it yet I feel pretty sure that I will end up getting the 2:1 gearbox and a sprocket combination yielding approx. 4:1 for a total of 8:1 from prop.
to crank.

Now for the hull size. I know you suggested going to 18' but I was leaning towards 16' for the simple reason of one less seam (joining of plywood sheets). Any estimate on what I would be sacrificing on 2' less? Is it worth the effort/labor to glue/laminate another section to get to 18'? If you think the effort is worth it and I have to do another seam; how big should I go to maxamize speed. Do I go to 24' (3 sheets of ply joined together)? Is there a point of diminishing returns?

If I was to stay to all of these parameters (possibly changing length based on your response to above):
Cat hulls 16' L X 1.5' H X 1' W (4' spread between hulls)
8:1 Ratio
75-80 cadence @ 75 watts

And I was unable to make my own prop; would I be able to use a 16x16 APC prop as described in earlier posts? If not any idea of what size I would need?

BTW: I purchased the ply (enough to go bigger if I want) and ordered my epoxy/glass materials and plan on starting construction as soon as they arrive (maybe this weekend). It's still only in the 50's here during the day but I hope to have it completed by the time the warm weather gets here.

Thanks for all your help
John

I57

04-05-2011, 07:00 AM

John
Go for the 16' hulls, not a huge amount of difference. If you were racing it would be different but a cruising/exercise boat is ok. The hull sizes will give you plenty of reserve bouyancy, allow you to carry extra gear. I would make the beam 6' as this will give you better stability and less drag caused by the waves off the other hull. One thing that might help is an access hatch on the deck of each hull. They have the dual purpose of draining the hull if you get a leak and also as a storage place to keep stuff dry. Good luck with the boat building.

Ian

portacruise

04-05-2011, 11:45 AM

Some builders have used an angle grinder gearbox in their boats, so that might be a cheaper alternative, especially if you can find a discarded one with a burned out motor. Probably would not work for racing, but should work for exercise purposes.

The 16X16 should work well enough for exercise purposes, or you can order just the replacement props from some commercial versions like seacycle if you need something more rugged. You can also use some of the commercial versions as a model for gear ratios. These are rented out at many water vacation spots and you can get a feel to see if it is more or less in the range you like. Then you can tweek the ratios a bit to fit your output more exactly.

Hope this helps.

Porta

Ian

I spoke to a guy at Mitrpak today who actually worked with Rick and Greg who was very helpful. Although they could special orderl/manufacture a 2:1 gearbox that would accept the bike cranks directly into the box (eliminating chain) the price was nearly double that of a conventional right angle box. Being my first endeavor, I think I will go with the less expensive option. Although I did not order it yet I feel pretty sure that I will end up getting the 2:1 gearbox and a sprocket combination yielding approx. 4:1 for a total of 8:1 from prop.
to crank.

And I was unable to make my own prop; would I be able to use a 16x16 APC prop as described in earlier posts? If not any idea of what size I would need?

John

JTA

04-05-2011, 07:37 PM

Ian/Porta

Thanks for your input/suggestions. They have all been very helpfull.

John

upchurchmr

04-06-2011, 10:29 PM

John,

I haven't followed the thread well yet, but got attracted by the question about the hulls. I built a catamaran row boat that has 11' hulls which is stripped planked (~3/16" strip thickness) with 6oz cloth inside and outside. max section above water is 6" wide by 4" freeboard, below the waterline is a semicircular shape bow to stern (except for the ends which transitioned to elliptical Mostly) the hulls support my 125# wife and are extremely easy to drive, no noticable wake. This kind of construction was relatively fast and each hull weighs about 18#. I'm a little messy so you could probably do better on weight. crossarms are 2# each, total width is 5 feet. Be carefull that you don't get the hulls too close together, I did a previous boat with 12" wide hull width at 5' beam and it was a dog with noticable wave interaction. If you want a really clean path thru the water, go semicircular. The simple mold was built in 1 weekend, the hulls were stripped in about 3 days each including decks.There was a trick to making the strips. I am pretty slow with the epoxy so that took too much time. You could see the boat in the thread on woodenboat.com forum, boat designs, "skinny, light rowboat". If you are heavier the length would have to be longer assuming you want to keep ~6" width for low wave making. I could give you a length guide if I knew your weight and what you think the entire boat would weight. Good luck.

Marc
Ian/Tom

Thanks for the responses.

Ian:
Is that the Hull from the pictures in your above post (#1053) that you are using the Flex shaft attached to your steering rudder arm? This is something I think I could tackle. So if I made two identical hulls (say 12' long) in a similar design/construction to what you are describing, would a bike crank to a gear box giving a ratio of 1:8 be sufficient to push the boat for exercise puposes? Again, I'm still unsure about the Flex shaft part (where to get), is it nothing more than what Porta described above (electricians flex drill attachment) or is this something that Rick W. has designed/produced for private use? I saw one of your earlier posts that shows your boat with the shaft (solid shaft) coming through the bottom of the hull. If I build the cat version and have a straight solid shaft coming down between the 2 hulls, I assume I would need a prop with a special pitch to compensate for the angle of the shaft right. I see you make your own props but that is beyond my abilities. This is why I was leaning towards the Flex shaft (if I could locate one) as it seems it comes right out of the gear box into the water, correct?

Tom:

Thanks but I don't think that I would be capable of doing a mold but I guess the Lay-up on braced veneer would be similar to glassing over a frame like Ian has shown, right? If you did this application, how many layers of fiberglass cloth would you need to use?

Thanks to all;
John

upchurchmr

04-06-2011, 10:36 PM

John,

After reading one of the last comments I have a suggestion. don't put in an access ports. My first boat had two for fastening the crossarms and they were the continual source of water leakage. The second boat has no openings and has never leaked (2 years). Don't get too much displacement for your weight or you will be like my first boat - totally unable to hold a course. be sure the ends are in the water, the second boat is ~1.5 inches under front and back and is a easy boat to keep on course.

Submarine Tom

04-07-2011, 12:04 AM

John, good point on the 6 oz cloth, that was a typo, I didn't mean 16 oz.

Semi-circular (cross-section) hulls for sure.

-Tom

I57

04-07-2011, 05:54 AM

I agree that the semi-circular section for the hull, gives you the smallest amount of wetted surface area. John mentioned he was building his boat out of sheet ply, difficult to make a half round section. A long thin hull 16' long x
1' beam can be easily built by having a rectangular section, the difference in performance would be minimal. The wave interaction between two cat hulls could be minimised by having two assymetrical hulls, the inside edge straight and the curve on the outside. Waves generated between the hulls would be small, might even make construction easier.
The access hatches I mentioned are about 150-200mm in dia. I have had a leak and this is the only way to get the water out short of cutting a hole. Its like getting a flat tyre, hardly ever happens but when it does thats when you need it.

Ian

upchurchmr

04-08-2011, 08:49 PM

Ian,

If you look at drag for airfoils it might suggest why you should not make an asymmetric set of hulls. A symmetric foil will a certail CD at zero angle of attack, straight ahead. when you add camber, or bend the airfoil, the graph of lift to drag moves over to the left, which means that at zero angle of attack, the CD has gone up. Since you have two hulls you get twice the penalty.

Being fixated on semicircular hulls, I can't quite understand how to build the hulls you drew. Of course, a square section flat bottom would be just as easy symmetric of asymmetric.

If you really want a square section, have you ever seen how Jim Brown built his searunner series of Trimarans? Basically he built the shape he wanted out of single curvature plywood, but did not connect the adjoining edges. then he rounded the mating edges as much as possible, leaving just the inner edges touching each other. Fiberglass the outside, fill the inside with epoxy and microballoons (for lightness) and fiberglass the inside. The result is a nicely rounded hull from plywood without compound curveature. His boats go around the world.

Marc

I agree that the semi-circular section for the hull, gives you the smallest amount of wetted surface area. John mentioned he was building his boat out of sheet ply, difficult to make a half round section. A long thin hull 16' long x
1' beam can be easily built by having a rectangular section, the difference in performance would be minimal. The wave interaction between two cat hulls could be minimised by having two assymetrical hulls, the inside edge straight and the curve on the outside. Waves generated between the hulls would be small, might even make construction easier.
The access hatches I mentioned are about 150-200mm in dia. I have had a leak and this is the only way to get the water out short of cutting a hole. Its like getting a flat tyre, hardly ever happens but when it does thats when you need it.

Ian

upchurchmr

04-08-2011, 08:57 PM

Paddle wheel fans,

About 10 to 15 years ago a group of bicyclist decided to win some local boat races for HPV. The boat ended up about 25', 8 feet wide (to fit on a trailer), 4 road race bikes welded together on top of a frame which supported twin inflatable huls. The paddle wheel was ~6' dia and ~7.5' wide. I never got to see it in action, but it was reported to throw a rooster tail about 30', went over 20 mph, and was really hard to turn. It was ridden by some dedicated road riders. Needless to say it demolished the competition and was retired after several years, because no one would enter the races.

One of the riders told me that each blade hitting the water sounded like a small shotgun, in rapid succession.

Brute force but I would have like to have seen a race.

Marc

I57

04-08-2011, 09:46 PM

Marc
Hate to sound dumb but what is the CD and what sort of forces does it apply to the hulls. The boat in question is for recreational purposes in sheltered waterways. A boat that is long and thin with a square section performs well and is easy to build. For this type of hull and where its used there is not a lot of advantage in a semi-circular hull. What I had in mind with the assymetric hulls was to reduce the waves between the hulls and keep the person dry.

Ian

upchurchmr

04-08-2011, 10:03 PM

Ian,

Sorry about the CD bs.

Cd is coefficient of drag. One of the parts of a drag equation would be a number that shows the relative effect of the shape you are using. The lower the Cd the less drag for a equal size foil section. I guess you would have to trust me (Im not sure I would if I was you - except this time) but all that means that the curved shape develops more drag than a symmetric one. I guess as usual the only way to really prove it would be to make a tow test. Not very likely I suppose. I can assure you with a good shape 6" wide with 4" separation, you will not see any appreciable extra drag between the hulls, even with a symetrical shape.

I am sure the square section hulls work, I would just rather go faster for my exercise effort. Different strokes and all that. My wife kept saying she wanted the exercise and was fine the my rather pitifull first attempt. Now with a better boat she says the same thing as she is leaving me in the dust, spray, whatever. Sounds like you had the same goal as I did. One of my design constraints was to take the boat to the lake in my pickup truck, and have my wife be able to launch it. 11' long works fine for her but I sink it almost to the decks. did you take a look at the boat? It is on the forum at woodenboat.com unders design/plans, "Skinny, light rowboat".

Good luck, Marc

Marc
Hate to sound dumb but what is the CD and what sort of forces does it apply to the hulls. The boat in question is for recreational purposes in sheltered waterways. A boat that is long and thin with a square section performs well and is easy to build. For this type of hull and where its used there is not a lot of advantage in a semi-circular hull. What I had in mind with the assymetric hulls was to reduce the waves between the hulls and keep the person dry.

Ian

xj35s

05-05-2011, 07:40 AM

I am going to derail this thread a little. I have a different issue. Big boat like a tug boat. I found these extremely cheap fan blades and was thinking of using two mounted solid with a rudder behind each. I wonder how these would run in water and if I could actually turn two of them by pedal power. I have the drive line consisting of a large Craftsman angle grinder gear box. I would link the two props together by bike chain inside the hull.

The price is almost free. I'm thinking maybe running as surface piercing so maybe 3/4 the prop is in the water. Think I could turn one around for counter clockwise props ?

I know this is Goofy and kind of far fetched But seriously, what do you think ? I could consider a deep cycle and electric motor to power these too. Will they push my flat bottom 250# chugger ?

I found the blades here. http://www.sciplus.com/category.cfm/subsection/18/start/34/maxrows/11/srch.fp/1
http://i168.photobucket.com/albums/u173/XJ35S/Chugger%20by%20Lewis%20boat%20works%20built%20by%20Earl%20Derby/AmericanScienceSurplus-MotorsBlowersandPumps_1304597896095.jpg

4'x4'x12' basic pocket cruiser.

http://i168.photobucket.com/albums/u173/XJ35S/Chugger%20by%20Lewis%20boat%20works%20built%20by%20Earl%20Derby/DSC03036.jpg

portacruise

05-05-2011, 08:26 AM

These fan blades are very inefficient in water compared to model prop blades which are available for $2 to $15 depending on size and pitch. I did try something like this blades and there is just to much resistance and they must be geared down quite a bit. You hull is also looking to be high resistance with the boxy shape.

Hope this helps.

Porta

I am going to derail this thread a little. I have a different issue. Big boat like a tug boat. I found these extremely cheap fan blades and was thinking of using two mounted solid with a rudder behind each. I wonder how these would run in water and if I could actually turn two of them by pedal power. I have the drive line consisting of a large Craftsman angle grinder gear box. I would link the two props together by bike chain inside the hull.

The price is almost free. I'm thinking maybe running as surface piercing so maybe 3/4 the prop is in the water. Think I could turn one around for counter clockwise props ?

I know this is Goofy and kind of far fetched But seriously, what do you think ? I could consider a deep cycle and electric motor to power these too. Will they push my flat bottom 250# chugger ?

I found the blades here. http://www.sciplus.com/category.cfm/subsection/18/start/34/maxrows/11/srch.fp/1
http://i168.photobucket.com/albums/u173/XJ35S/Chugger%20by%20Lewis%20boat%20works%20built%20by%20Earl%20Derby/AmericanScienceSurplus-MotorsBlowersandPumps_1304597896095.jpg

4'x4'x12' basic pocket cruiser.

http://i168.photobucket.com/albums/u173/XJ35S/Chugger%20by%20Lewis%20boat%20works%20built%20by%20Earl%20Derby/DSC03036.jpg

Jeremy Harris

05-05-2011, 09:17 AM

The key to getting good efficiency is to use a prop with as high an aspect ratio (that's the length of the blade divided by the width of the blade) as possible.

Fans and conventional boat props use wide blades for two reasons. One is that it allows a smaller diameter to absorb a fair bit of power, the second is that wide blades are easier to make strong enough to take the loads. The big downside is that wide blades are inefficient, in fact grossly so when you get to multiple blades that almost fill the available prop area.

As has already been mentioned, model aircraft props work pretty well and are dirt cheap. Better still is to make a prop, not really hard to do and it means you can get a good match to the speed you like to turn the cranks and the ratio of your gear drive.

Bear in mind that an average person can only put out about 100 watts (around 0.13hp) continuously, maybe two or three times that figure in short bursts. That's not a lot of power, so everything from the boat hull, through the drive system to the prop needs to be as efficient as you can make it. Even a 5% change in prop efficiency makes a worthwhile difference when you're only working with such a small amount of power to start with.

Jeremy

messabout

05-05-2011, 09:29 AM

XJ35s; Get out the saw before it's too late. Raise the bottom of the chugger at the transom. That is to say, get the bottom at the transom above the water line. The way it appears, the boat will drag part of an ocean behind it. The bottom is shaped as if for a planing boat which is very inefficient in displacement mode.

xj35s

05-05-2011, 10:07 AM

Okay. Thanks all. Thread back on the rails now.

Yes it is not a planing hull. Basically a barge. A wooden camper that floats. Not really meant to travel far either. I have a 5 HP briggs 4 stroke for it. I'll stick with that. Those props reminded me of some of the springer tug RC boats I've seen and I thought, HEY!

I am planning on a strip planked canoe. I'll pedal that...

portacruise

05-05-2011, 02:22 PM

Jeremy:
Interesting observation on aspect ratio. The question I have is what is the minimum width of blade where this aspect ratio breaks down and what factors of torque and rpm are involved. Maybe too complex to consider on this forum, I suppose.

I find with my actual on the water trials of hundreds of model plane props, that things can vary all over the place as far as aspect ratio. Some of this may be because of blade design which varies with the manufacturer. But even with APC which usually has more efficient blades, the wider electric blades get considerably better efficiency that the standard gas blades several pitches and diameters within the comparable range. This is especially true in the smaller diameters. For example, a wider APC10X7 electric blade is more efficient than any of the narrower 9 or 11 standard blades in my low power (40 watt) electric applications. Don't know if this would hold pedal boats though...

Porta

The key to getting good efficiency is to use a prop with as high an aspect ratio (that's the length of the blade divided by the width of the blade) as possible.

Fans and conventional boat props use wide blades for two reasons. One is that it allows a smaller diameter to absorb a fair bit of power, the second is that wide blades are easier to make strong enough to take the loads. The big downside is that wide blades are inefficient, in fact grossly so when you get to multiple blades that almost fill the available prop area.

As has already been mentioned, model aircraft props work pretty well and are dirt cheap. Better still is to make a prop, not really hard to do and it means you can get a good match to the speed you like to turn the cranks and the ratio of your gear drive.

Bear in mind that an average person can only put out about 100 watts (around 0.13hp) continuously, maybe two or three times that figure in short bursts. That's not a lot of power, so everything from the boat hull, through the drive system to the prop needs to be as efficient as you can make it. Even a 5% change in prop efficiency makes a worthwhile difference when you're only working with such a small amount of power to start with.

Jeremy

Jeremy Harris

05-05-2011, 02:49 PM

portacruise

05-05-2011, 08:45 PM

It's complex, because as the aspect ratio increases the blade torsional stiffness decreases, making the blade tend to de-pitch under load. This effect is more pronounced with model aircraft props because, when used in water, they are subjected to loads that are significantly greater than when used in air, even accounting for the difference in rpm.

I've made some blades using an APC model prop as a buck for a mould, moulding the blades using a mixture of carbon fibre tow and biaxial weave glass cloth as the reinforcement and epoxy resin loaded with bronze powder. The result was better performance than the glass reinforced nylon APC prop, presumably because the blades are much stiffer.

I'm pretty sure (but not certain) that the wider plastic blades are torsionally stiffer than the narrow ones, so are less subject to pitch change under load. This is only a theory, but the limited evidence I have to date seems to support it. It also explains why my narrow, Rick Willoughby inspired, stainless steel prop works better than a similar size and pitch plastic aircraft prop.

Jeremy

That's the thing about the electric props, they are wider across the blade, but much thinner in slice and flex more than the narrow across the blade gas props. The design is quite different in appearance and they are meant for lower rpm, so maybe they have less slip or less friction due to thinner slice. My top speed is only 3 knots, but I get greater efficiency (measured up to 20% less current draw at the same boat speed). Even the wider WOOD electric props seem to do better than narrow, but some have unusual cupping in their blade contours.

Porta

Jeremy Harris

05-06-2011, 01:27 AM

It may have something to do with prop rpm, too. As I recall, you're running these props quite fast, faster than a pedal powered boat or my electric drive, runs (I'm running at around 300 to 400pm). As blade loading is proportional to the square of rpm, even a small increase makes a big difference. Also, at higher rpm blade thickness (not the chord of the blade) plays a bigger part, as to get low drag the chord/thickness ratio needs to be high, too. This may play a greater part in the overall losses once you get, say, a 12" prop up above around 600 to 800rpm and may be why you're getting better results with the thinner section, wider chord, props.

The 13" diameter stainless steel props I've made are 3mm thick in the centre with about a 20mm maximum chord. They taper to a chord of about 8mm and a thickness of about 1.5mm at the tip. The aerofoil section I used approximated to an E192 section, which is fairly thin, probably similar to that used on the electric aircraft props. The thicker APC props seem to use a Clark Y aerofoil, which is a fair bit thicker and less well-suited to running at high Reynolds numbers.

Jeremy

portacruise

05-06-2011, 10:16 AM

My top speed motors are rated at 450 rpm no load, so run below that under load using props under 12", most in the being 10" depending on how much power/range I want.

Anyway here is a site that has a large prop selection with pictures which can be enlarged to see the different shapes and sometimes designs. You can switch to different manufacturers to compare. Generally the Master props come in scimitar, wood, fiberglass, and the last is best: wood electric which I find is the best for that brand, but ONLY at low RPM, say 300 or so.

http://www.gravesrc.com/category_s/161.htm?searching=Y&sort=7&cat=161&show=30&page=2

Hope this is of interest, thanks for your comments.

Porta

It may have something to do with prop rpm, too. As I recall, you're running these props quite fast, faster than a pedal powered boat or my electric drive, runs (I'm running at around 300 to 400pm). As blade loading is proportional to the square of rpm, even a small increase makes a big difference. Also, at higher rpm blade thickness (not the chord of the blade) plays a bigger part, as to get low drag the chord/thickness ratio needs to be high, too. This may play a greater part in the overall losses once you get, say, a 12" prop up above around 600 to 800rpm and may be why you're getting better results with the thinner section, wider chord, props.

The 13" diameter stainless steel props I've made are 3mm thick in the centre with about a 20mm maximum chord. They taper to a chord of about 8mm and a thickness of about 1.5mm at the tip. The aerofoil section I used approximated to an E192 section, which is fairly thin, probably similar to that used on the electric aircraft props. The thicker APC props seem to use a Clark Y aerofoil, which is a fair bit thicker and less well-suited to running at high Reynolds numbers.

Jeremy

I57

05-20-2011, 08:58 AM

Have used the directional prop a few times now and have decided to go back to the dipping rudders. Disadvantages were a large turning cicle and a lot of force to push the shaft from side to side. The turning arm I used was heavy to take the load as well as heavier steering arm and lever. Glad I tried it as now I know it does work but has its limitations.
The dipping rudders are bolted to a piece of angle which is attached to a drum. One end is fixed with a piece of shock cord to keep the rudder out of the water. The other end is attached to a lever to lower it into the water. Have kept the rudders about 100mm away from the side of the boat. I can adjust the rudder angle to see what works the best, also allows me to fit different rudders later on if I need to. Next step is to get it on the water and see how well it works.

Ian

Submarine Tom

05-20-2011, 12:08 PM

Have you built any lift into those dippers or are they symmetrical?

You could reduce your drag slightly by doing so...

-Tom

I57

05-20-2011, 07:16 PM

Tom
The rudders are flat on the outboard side and aerofoil shape on the inside.

Ian

Submarine Tom

05-21-2011, 01:51 AM

Interesting, thanks.

-Tom

Coach Dave

06-08-2011, 10:42 PM

I've made several outings now in my pedal powered boat and want to share some things that I learned along the way. I attached a picture of the drive unit. I used an old steel (chrome moly) bike frame and cut off what I didn’t need. The old bottom bracket wasn’t function so I replaced it. The 52T chain ring was pretty worn so I flipped it over. The crank arms were fine. I added Look Arc compatible pedals to mate with my road bike shoes. The bottom sprocket is a 14T track sprocket (3/32) threaded onto an old freewheel hub. I cut down the freewheel hub, bored it out and epoxied it to the gear head of a broken string trimmer. The track sprocket turns 13 revolutions to 19 revolutions of the flexshaft. That gives me 5.43 flexshaft revolutions per crank arm revolution. The flexshaft drives an APC 16x16 prop. With 8 people on board and a head wind I averaged 4.8 MPH for a 3 mile stretch. I mounted a magnet on the left crank arm (black band, visible just above the chain ring) and programmed the odometer for the prop pitch and gear ratio, assuming 5% prop slip. I haven’t calibrated the slippage yet so the 5% is just a guess. I’ve gone about 40 miles with this setup. This weekend I want to try out a 16T sprocket for a 4.75 gear ratio. That should let me spin faster and be a little closer to my preferred RPM range. I felt like I pushing slowly instead of spinning with the 14T sprocket. The steering wheel is below my right elbow. The rope on the drum turns the rudder. I made a kick-up rudder. The rope under the drum swings the rudder up and down. I am sitting on a boat cushion and have a youth size life vest behind my lower back as a lumbar support – very comfortable for several hours pedaling. The 2”x3”x8’ white aluminum in front of the bike frame is the aft strut that connects the main hull (28’x2’ overall) to the outrigger (24’x6” overall). Both hulls are 1/8” 3-ply birch stitch & glued construction with one layer of 6 oz. fiberglass on the inside. The outside has one layer of 6 oz. and one layer of 9 oz. fiberglass on it.

The next picture shows the prop, flexdrive and prop height adjustment. My son Daniel has red hair. His hands are on the flexshaft. I used ¼”x8’ T-316 round stainless steel stock. I ground one end square to fit the flexdrive side of the string trimmer gear head. I tapped the other end to sandwich the prop between locknuts. The parallelogram next to Daniel’s hands adjust the prop height. Initially I made the prop free swimming. At low power levels it worked fine. As I put more torque on the crank arms the prop started riding up, sucking in air and made the prop slip. It made an interesting sound but limited how much power I could transmit to forward motion. Then I came up with a strut to hold the prop at a preset level. That worked but would occasional foul up with weeds. Then I hit something hard and broke the strut. The present version is designed to swing up in case of a hard impact rather than breaking. I use a cable tie to attach the shaft to the strut. The 4 holes behind Daniel’s calf muscle are where the rudder bolts on. The six seats are stacked up in front of me. They sit on rails that run the length of the 12’ open cockpit area. Grandpa enjoyed the day immensely – watching how everything fit together.

I have more pictures to post - to be continued!

Coach Dave

06-08-2011, 10:55 PM

Picture#1 the rudder is installed now and flipped up vertically right behind my back. The weight is fairly well centered on the two wheeled dolly so it is easy to move. Grandpa is guiding the outrigger. The forward strut attaching the outrigger to the main hull is visible. Next to the forward strut is a 2” galvanized pipe sticking up with a white cap on it. That is the tabernacle where I hope to put a mast for a wing sail someday.

Picture #2 You can see most of the aft section of the open cockpit area. Since the open area is 12’ long I put a yoke across the center for stiffness. Most of the outrigger is visible.

Picture #3 You can see most of the forward section of the open cockpit area. Tim and Kwang are ready to get in the solo kayaks.

Picture #4 Five people are already seated, the cooler is bungee corded onto the forward strut, and Daniel is ½ on. Several onlookers want to see what this contraption will do.

Picture #5 Six people are on board. Tim escorts us in a 9 ½’ solo kayak. Notice that we are trimmed with too much weight aft. I made two seats for the nose that I want to test this weekend.

Picture #6 We are cutting through the water with very little ripple. Nice shot of the rudder control arms, prop shaft, prop height adjustment parallelogram and outrigger.

Picture #7 All systems are go as we head out for the main channel. It is 3 miles to Samsons Island. Kwang got tired paddling the solo kayak so he returned to the “mother ship”, climbed aboard and we towed his kayak. We hiked around Samsons Island, bungee corded both solo kayaks on top of the nose of the mother ship and had eight people on board for the return trip.

I’m having a lot of fun with this boat. I’m taking it on a 3 day/2 night boating/camping trip this weekend.

Submarine Tom

06-08-2011, 11:08 PM

Well that's certainly impressive. Well done.

-Tom

portacruise

06-10-2011, 12:16 AM

Very interesting, thanks for posting.

I think the flex shaft may be a little too thin and weak for the load. If you check the archives, Rick used 10mm or at least 8mm SPRING steel, which is much stronger, for just a single person boat. If you really lean into the pedals or accelerate rapidly, may get a failure using 1/4" ss. I also carry a backup shaft and props in case or failure, and have had to use it on a couple of occasions.

Hope this helps.

Porta

Picture#1 the rudder is installed now and flipped up vertically right behind my back. The weight is fairly well centered on the two wheeled dolly so it is easy to move. Grandpa is guiding the outrigger. The forward strut attaching the outrigger to the main hull is visible. Next to the forward strut is a 2” galvanized pipe sticking up with a white cap on it. That is the tabernacle where I hope to put a mast for a wing sail someday.

Picture #2 You can see most of the aft section of the open cockpit area. Since the open area is 12’ long I put a yoke across the center for stiffness. Most of the outrigger is visible.

Picture #3 You can see most of the forward section of the open cockpit area. Tim and Kwang are ready to get in the solo kayaks.

Picture #4 Five people are already seated, the cooler is bungee corded onto the forward strut, and Daniel is ½ on. Several onlookers want to see what this contraption will do.

Picture #5 Six people are on board. Tim escorts us in a 9 ½’ solo kayak. Notice that we are trimmed with too much weight aft. I made two seats for the nose that I want to test this weekend.

Picture #6 We are cutting through the water with very little ripple. Nice shot of the rudder control arms, prop shaft, prop height adjustment parallelogram and outrigger.

Picture #7 All systems are go as we head out for the main channel. It is 3 miles to Samsons Island. Kwang got tired paddling the solo kayak so he returned to the “mother ship”, climbed aboard and we towed his kayak. We hiked around Samsons Island, bungee corded both solo kayaks on top of the nose of the mother ship and had eight people on board for the return trip.

I’m having a lot of fun with this boat. I’m taking it on a 3 day/2 night boating/camping trip this weekend.

I57

06-12-2011, 03:11 AM

Coach Dave - What a great setup, you could start taking tourists. Even better, get all 8 people pedalling, would be interesting to see how fast it would go. It shows how much power can be generated by a pedal powered boat. A single person trying to paddle with the same load would get nowhere.

Now for my news, I've modified my boat yet again. I tried the dipping rudders but could not get them to work right. The boat would not turn any better and the rudders wouldn't always kick back up clear of the water. So now I've gone back to the directional prop but with a better setup. I made the shaft angle steeper to get more of the shaft in the water enabling me to swing it further side to side. Another bonus was being able to lower the seat, saving weight and getting a lower CG. I can turn a lot better now and if I lean into the turn and dig the outrigger in the boat comes round as good as with a rudder.

Ian

upchurchmr

06-12-2011, 09:27 AM

IM57

Looks like you are using the outrigger as a drag device. Those work pretty well as shown by dragging one oar on a row boat. But you are slowing yourself down quite a lot I imagine.
Since you are creating drag to turn the boat, shouldn't you reverse the outriggers? An asymmetric outrigger should provide "lift" towards the curved side. If you swap the outriggers side to side, the inboard one (on the turn) should also provide lift to the outside of the turn. Since the outrigger is aft of the center of the boat, it should also provide a additional direct turning power.

Nice looking boat. Can you keep both outriggers out of the water on a straight course?

Is there any reason not to dip a normal rudder? Pull it up when you don't need it, stick it in and turn it when you do. With 75 pages to this thread, I probably missed the answer.

Marc

I57

06-13-2011, 02:32 AM

Marc
I am using a steering arm to move the prop shaft side to side to steer the boat instead of using a rudder. Because the shaft will only turn so far the turning radius is a lot more than with a rudder. The outriggers are set so that they just touch the water. By leaning into the turn and digging in the outrigger the boat turns a lot tighter, just a way of turning a bit quicker if I need to. I see what you mean about reversing the outriggers, would give a greater force to turn the boat. The hull is narrow and deep and has always been slow on the turns, even when I was using a rudder. I did try Rick’s dipping rudders a couple of times but could never get them to work properly. The boat has minimal drag in the water, the skeg that moves the prop shaft is 25mm x 3mm aluminium. The boat is 5m long with a 200mm beam, on a straight run I can have one outrigger out and one skimming the water.

Ian

portacruise

06-13-2011, 03:55 PM

Ian, for low speeds or tight positioning such as in rivers or creeks, prop steering may be the only way to go, other than paddling. Prophish also uses this method for their craft, with some kind of swivel joint at the prop end http://www.prophish.com/home.html So you can pedal in places where rudders don't work. I think you have invented a clever setup for doing this type of steering.

Enjoy.

Porta

Marc
I am using a steering arm to move the prop shaft side to side to steer the boat instead of using a rudder. Because the shaft will only turn so far the turning radius is a lot more than with a rudder. The outriggers are set so that they just touch the water. By leaning into the turn and digging in the outrigger the boat turns a lot tighter, just a way of turning a bit quicker if I need to. I see what you mean about reversing the outriggers, would give a greater force to turn the boat. The hull is narrow and deep and has always been slow on the turns, even when I was using a rudder. I did try Rick’s dipping rudders a couple of times but could never get them to work properly. The boat has minimal drag in the water, the skeg that moves the prop shaft is 25mm x 3mm aluminium. The boat is 5m long with a 200mm beam, on a straight run I can have one outrigger out and one skimming the water.

Ian

upchurchmr

06-13-2011, 05:40 PM

IM57

As I remember you are using a square cross section on the main hull. I'm sure you will get better than great directional stability, just not sure you need it all.

I also like the steering setup with the prop, so long as you don't need quicker response. The mechanism seems simple and clever. (Usually not combined in the same system).

If you were ever interested in a round bottomed boat that maintained the directional stability, increased the steering response and was relatively simple to build, please drop me an email. I built a similar hull (just too short for you) and had a way to strip plank the bottom that took very little time. At least I thought it was quick compared to other less simple shapes.

Too bad you are so far away, I would build you the bottoms just to show how it could be done. My idea was to use everything above the waterline as plywood, so you would maintain the majority of the simplicity and quickness of build. I would build the hull below the waterline as a symmetrical configuration (fore and aft), so that one mold 2.5M long would be enough. Basically a table top tool.

One of these days I am going to have to copy the drive mechanism and put my money where my mounth is.

Have fun.

Marc

I57

06-14-2011, 04:37 AM

Marc
Thanks for the offer of how to build with strip planking. It might be a while before I build another boat. I am still looking at ways to improve the current boat, not sure what yet. The boat started with flex shaft and dipping rudders then to a fixed rudder. After that it was a straight shaft trying a few different props, then back to a flexible shaft and then the directional prop. Back to the dipping rudders then back to the directional prop which is the current setup. Keeps the brain working and keeps me busy.
I am restricted in the length of 5 metre as that is the maximum length I can store in my garage. If I did the same thing as the rowing shells where sections are bolted together it would make transport and storage easier. Something to think about for the future.

Ian

Coach Dave

06-18-2011, 06:33 AM

Jeremy Harris

06-18-2011, 06:52 AM

Porta,

You are correct about the 1/4" stainless steel driveshaft. It does work and I've gone 57 miles with it so far. When I am cruising at 4.8 MPH the shaft seems to be adequate. When I push it up to 6.0 MPH the driveshaft feels very springy and prevents me from developing more thrust. I measured the flexshaft torsional compliance at 4.42 Nm/Rad. I'd like to tripple that by making it stiffer. I'm searching for the right materials and will post what I learn. Until then I posted

http://www.youtube.com/watch?v=uAUb47sUdjw

from may trip last weekend on the Ocklawaha River and Silver River. I pedaled the outrigger kayak 17 miles and paddled a solo kayak 11 miles. We had 10 people on the trip, 6 solo kayaks and the outrigger kayak served as the mother ship. I averaged 5 people in the outrigger kayak although at one point all 10 people were either in the mother ship or hanging onto it.

That's impressive that you can pedal such a big craft so well.

One way to stiffen the shaft might be to just lay up a carbon fibre/epoxy sleeve over it. This is pretty easy to do, as you can get hollow braided sleeves woven from carbon fibre that you just slip over the existing shaft, coat with epoxy resin and then bind with either electricians insulating tape or heat-shrink sleeving to temporarily pull it tight to the shaft (once the resin has cured you can take the tape/sleeving off).

Here's a link to a supplier across your side of the pond that shows the stuff I'm talking about - I don't know if these are the best people to buy it from over there though. http://www.cstsales.com/carbon_braid.html

Carbon fibre is a fair bit stiffer than stainless steel, so my guess is that one or two layers of this stuff will significantly increase the torsional stiffness of your shaft, without making it appreciably heavier or that much bigger in diameter.

Jeremy

upchurchmr

06-18-2011, 08:12 AM

Coach Dave,

Great video, you must have been an intense bicyclist previously to put in as many miles as you have. Probably still are I assume.

Any idea what causes the knocking noise as you pedal? That was the only surprise to me.

Jeremy, thanks for the web site, I never noticed the braid or thought of the application.

Marc

Jeremy Harris

06-18-2011, 08:29 AM

I'd hazard a guess that you could just use a bit of aluminium, or maybe even plastic, tube as the core for a carbon fibre sleeved drive shaft like this, as the carbon fibre would be taking pretty much all the load. It might be an idea to dangle the shaft vertically, perhaps with a weight on the end, whilst the resin is curing, just to ensure that the shaft remains as straight as possible.

Jeremy

portacruise

06-18-2011, 01:31 PM

A chap from the hpb list hpv-boats@hupi.org <hpv-boats@hupi.org> found powder coated sewer rod at this address http://www.flexmax.com/maxlife/cat1.html Not sure if it is spring steel, though it is available to 3/8" diameters.

The only spring steel I have been able to find easily in USA is electrician's drill bits but only in 1/4" maximum diameter. Still, I think it would be stiffer torsionally than SS, eliminating the rubbery feel....

Porta

Porta,

You are correct about the 1/4" stainless steel driveshaft. It does work and I've gone 57 miles with it so far. When I am cruising at 4.8 MPH the shaft seems to be adequate. When I push it up to 6.0 MPH the driveshaft feels very springy and prevents me from developing more thrust. I measured the flexshaft torsional compliance at 4.42 Nm/Rad. I'd like to tripple that by making it stiffer. I'm searching for the right materials and will post what I learn. Until then I posted

http://www.youtube.com/watch?v=uAUb47sUdjw

from may trip last weekend on the Ocklawaha River and Silver River. I pedaled the outrigger kayak 17 miles and paddled a solo kayak 11 miles. We had 10 people on the trip, 6 solo kayaks and the outrigger kayak served as the mother ship. I averaged 5 people in the outrigger kayak although at one point all 10 people were either in the mother ship or hanging onto it.

Coach Dave

06-18-2011, 09:54 PM

Ian,
If I could get 8 people pedaling and actually develop 8 times as much power we could go twice as fast since speed increases with the cube root of power. Every time you double the power you can go 26% faster. Given the weight of my boat plus 4 passengers (1000 lbs total) and the hull dimensions Rick W. estimated 110W is required to move my hull at 4.8 MPH. That is a speed I can maintain for several hours. At 6.0 MPH Rick W. estimated 210W is required to move my hull. At that speed however my 1/4" ss driveshaft is very springy and limits my top speed.

Jeremy,
I want to try spiral wrapping 11 oz. unidirectional carbon fiber over a pultruded fiberglass core. The fiberglass can endure lots of flexing and the carbon fiber should boost the torsional compliance. In theory, the flexshaft should handle a larger load without fatiguing and my top speed will be limited by my legs.

Marc,
I am more of a runner than a cyclist. With my current schedule I typically get out and ride once a week. If I am taking the kayak out I pedal it instead of the bike. The big difference in position is that on my road bike the pedals are under me so I can put my weight on them. The kayak pedals are out in front of me like a recumbent bike so I can't stand on the pedals to get more torque.

Coach Dave

06-18-2011, 09:59 PM

Marc,
The knocking sound is the driveshaft hitting the strut that I use to adjust the height of the prop. If I let the prop get too close to the surface it will suck in air and the prop slips. If I run with the prop too deep I risk hitting obstructions or getting weeds tangled in the prop.

I57

06-23-2011, 04:37 AM

Tried out the outrigger steering method today, it did turn tighter. I mounted the asymmetric outriggers the opposite way with the flat side outboard and the curved side inboard. The rudders were rigidly fixed to the aft end of the outriggers, 100mm deep x 150mm long set at 30 deg. Leaning into the turn I could only immerse the rudder about 10-15mm, if I had leaned any further I might have gone for a swim. The main turning force came from the shape of the outrigger, the rudder had little effect. The rudders were set 50mm above the waterline, any lower and they would have been causing drag from the waves. With the directional prop hard over and leaning into the turn it is the best I’ve had out of this boat. Tried turning using the outriggers only keeping the prop running straight and the boat was very slow to turn, seemed better to port than starboard. This may have something to do with the prop rotation.
It might work better with better designed outriggers but the main turning force came from the directional prop.

Ian

upchurchmr

06-23-2011, 07:13 AM

I57

Interesting experiment with the rudders and switching the outriggers. Turning an idea into something usefull is the best part of this forum.
Congratulations.
Perhaps you could think of a way to try this one. Bow rudders a generally very powerful, just hard to control. If you put a short "rudder" attached on the bow, no deeper than the current bow you could have it straight ahead and not affect drag, except for a few square inches of wetted surface. During a turn, the bow would get a push, the stern also at the same time and you might get a better response. I don't have a suggestion as to how large.

Marc

atomas

06-26-2011, 07:20 PM

Hello all! greetings from Portugal!

I'm new to this forum, and first of all I want to congratulate all to the useful information that you post on this blog about HPB.

I'm currently in the start-up phase of my recumbent catamaran, and I have 2 main doubts that I hope someone could help.
1 - I made 2 hull designs that have subtle differences basically in the front of the hull. One is more agressive than the other, and I would like no now if there could be any susbtancial difference in the hydrodynamic performence.

You can see the drawing here (https://docs.google.com/viewer?a=v&pid=explorer&chrome=true&srcid=0B6DO3WYWzjhiZGMzYmFmOGUtNjU5Mi00NjI2LWFhNTQtNjA4N2YwOTI2NmQ5&hl=pt_PT)

2 - I will make the hull model to construct the mould in fiberglass. I planed to make a fisbone like model in wood and fill in with styrofoam. The problem is that I want to had a finishing material to guarantee a smooth and polished surface, ready to apply gelcoat to make the mould. Do you know witch material should I adopt for finishing purpose and the same time, neutral to styrofoam?

Thanks,

Artur

More information about the project in my blog:www.purepedal.com (purepedal.com)

upchurchmr

06-27-2011, 10:58 PM

Atmos,
If you use styrofoam, you need to fiberglass it in order to have a solid enough shape to make a mold from. I don't think there is any way around lots of sanding, then painting before you attempt to make the fiberglass mold.

Many mold makers will make a strip planked male hull shape in order to relatively quickly get a strong enough shape for making the mold. I believe you should still fiberglass it so that the mold will match the male shape you make exactly.

Or you could just make two strip planked hulls, fiberglassed and be able to go pedalling quicker and for a cheaper price. If you paint the hulls you can avoid lots of labor to make a nice finish on the wood. Then if you decide the hulls work the way you want you will have the male hull shape to make a mold.

I don't think there is any difference in the two hull shapes you showed, except the Solution B will turn a tiny amount easier.

Have fun.

Marc

Coach Dave

06-28-2011, 09:52 PM

Hi guys,
i am new on this forum,got here because i have an interest in pedalpowered
boats.
Has anyone considered or tried using a pedalpowered generator to power an electric outboard motor?
I have been toying with this thought, because it would not need a mechanical
transmission from pedal to prop:idea: :confused:

I built a pedal powered generator unit that I used to run a trolling motor on a canoe back in 2009. See picture #1. I made a wooden flywheel to supply energy during the "dead zone" at the bottom of the pedal stroke. The flywheel was sized to spin a 500 watt electric scooter at the right RPM to power the trolling motor. The seat back is leaning against the unit. Picture #2 shows us carrying the pedal unit to the lake. Picure #3 is the trail marker to Fontana Lake in the Great Smoky Mountains where we went canoeing/kayaking/camping in September 2009. Picture #4 is a side view. The trolling motor is mounted at the bow and is free to rotate 360 degrees. I have a drum on the trolling motor shaft with a rope around it to point the motor in any direction. No rudder - the trolling motor provides thrust in any direction that you want to go - forward or backwards. I also liked the fact that there is no mechanical linkage from the pedals to the prop. The downside is the poor efficiency in converting pedal power to thrust. We went 20 miles on the lake camping at water accessible sites. Picture #5 is a view from the rear. Picture #6 shows us cruising along the lake. Picture #7 - We unloaded our camping gear at Double Island and Michael tries out the pedal unit. Notice how high the seat is above the water line. A power boat went by, the wake rocked the canoe, Michael and the pedal unit went overboard. The water is 400' deep! No worries - Michael can swim and the seat base is filled with foam. We got Michael and the pedal unit back in the canoe. The pedal unit continued to work fine - we went about another 10 miles with it. When I got home I took the saw to the seat base and made it about 6" shorter to lower the center of gravity. Picture #8 - the survivors of our first ever pedal boat camping epic journey.

alanrockwood

07-04-2011, 12:23 AM

Jeremy Harris

07-04-2011, 01:19 AM

Coach Dave,

Do you have an estimate for the loss of efficiency using the generator-motor concept? I think motors and generators can be built to be quite efficient. It seems to me that an overall efficiency of >80% might be possible, possibly even in the 90% range. If so then the simpler coupling of the pedals to the prop for the electro-mechanical drive might more than justify a possible small loss of efficiency.

How was the system with respect to weight?

I looked very closely at this option for my solar electric boat; having a pedal powered option as a backup sounded reasonable. Motor and generator efficiency, using good quality brushless units with decent magnets and a good copper fill ratio, is up around 88 to 90% for each, so there will be around 10% power loss in the generator and another 10% loss in the motor, making a total power transmission efficiency of around 80%.

Propeller efficiency rarely exceeds about 85 to 90% for a really well-matched large diameter, slow rpm prop driving a pedal powered boat, so you could expect a total system efficiency using the pedals - generator - motor - propeller arrangement of around 65 to 70%. This is lower than with a direct drive, where the transmission losses will be negligible (maybe a couple of percent at most), but not too shabby when compared with a conventional propulsion system. It's also still probably more efficient than rowing or paddling.

One thing that interests me about this option is the ability to add a small battery to store excess pedal power and allow that extra power to be used for manoeuvring, going astern etc. The added flexibility this would give might make the efficiency loss worthwhile.

Jeremy

portacruise

07-05-2011, 09:55 AM

There has been a lot of development is electric drive systems for land bike since the 90's by several chaps from Switzerland. Here is a paper which can be followed for other references: http://www.hupi.org/HPeJ/0015/SeriesDriveHybridVelomobiles.pdf

The series hybrid would appear to be better than the parallel. Load leveling would seem to be the chief advantage as one could take advantage of continuing to pedal while stopped or with wind to store some energy. Better ergonomics and lower maintenance are also a plus.

The efficiencies have been as high as 90% in direct drive land vehicle situations as I recall, but would be lower due to prop slippage in a boat...

Hope this helps.

Porta

portacruise

07-05-2011, 02:37 PM

Another reference: http://endless-sphere.com/forums/viewtopic.php?f=2&t=4711

This topic was also discussed on the bike power assist list may years ago. Some more advantages for boats would be ability to change output gear ratios electronically, thus easily changing torque and rpm, which might allow efficient matches with smaller props when needed. Maybe, hands free steering, and possible stability of very narrow efficient hulls without outriggers....

The lightest and most efficient systems were configured along the lines of selsyn drives which did not encounter battery conversion losses, as I recall.

P.

Jeremy Harris

07-05-2011, 03:05 PM

Battery conversion losses are negligible with lithium cells, certainly less than 2%. The really big problem is that very high efficiency motor/generators are very expensive, as they need halbach arrays, a high copper fill and little or no iron content. Currently the very best motors (or generators) are probably the Australian CSIRO motors, but they have a very hefty price tag.

I worked with Selsyn/Synchro systems back in the early 70's (they were the way in which pretty much every radar connected the antenna rotation to the PPI rotation, by using the motor driven antenna to drive rotating scan coils at the base of the PPI tube). Their efficiency is very poor, less than 50%, as they are optimised for position synchronisation and don't allow any relative shaft slip.

A pedal - generator - motor - propeller system using a pair of CSIRO motors would probably get close to 95% overall efficiency. There's more on these motors here: http://www.csiro.au/resources/pf11g.html

Jeremy

portacruise

07-05-2011, 03:50 PM

Jeremy:

Thanks for the link, things have progressed quite a bit since I was last looking at this.

Great info on the battery losses. I would have expected the round trip losses to be higher because of mechanical> electrical> chemical conversion and then back through the 3 stages.

Porta

Battery conversion losses are negligible with lithium cells, certainly less than 2%. The really big problem is that very high efficiency motor/generators are very expensive, as they need halbach arrays, a high copper fill and little or no iron content. Currently the very best motors (or generators) are probably the Australian CSIRO motors, but they have a very hefty price tag.

I worked with Selsyn/Synchro systems back in the early 70's (they were the way in which pretty much every radar connected the antenna rotation to the PPI rotation, by using the motor driven antenna to drive rotating scan coils at the base of the PPI tube). Their efficiency is very poor, less than 50%, as they are optimised for position synchronisation and don't allow any relative shaft slip.

A pedal - generator - motor - propeller system using a pair of CSIRO motors would probably get close to 95% overall efficiency. There's more on these motors here: http://www.csiro.au/resources/pf11g.html

Jeremy

Coach Dave

07-05-2011, 09:42 PM

Coach Dave,

Do you have an estimate for the loss of efficiency using the generator-motor concept? I think motors and generators can be built to be quite efficient. It seems to me that an overall efficiency of >80% might be possible, possibly even in the 90% range. If so then the simpler coupling of the pedals to the prop for the electro-mechanical drive might more than justify a possible small loss of efficiency.

How was the system with respect to weight?

Alan,

My "generator" is the permanent magnet motor salvaged from my son's old electric scooter. It is rated at 500W. I don't have a convenient way to measure its efficiency. It weighs 9.4 pounds. It is cylindrical, 4 1/8" diameter and 5 1/8" long. The propeller is probably not very efficient - a high RPM, low diameter & pitch weedless model which is typical on trolling motors. I suspect there is ample room for each component in the drivetrain to be improved with time, effort and money. I went the cheap route using salvaged parts, got a functional system although I can't claim it is optimized. Mechanically decoupling the power generation from the propeller shaft drive does have advantages. A common application is a diesel-electric locomotive. A diesel engine turns a generator that powers a motor to drive the wheels. The torque/speed characteristics of the motor are tailored to the load dynamically - huge torque at low RPM to high power / high RPM when cruising down the track.

Coach Dave

Jeremy Harris

07-06-2011, 01:48 AM

If that scooter motor is a typical Chinese made brush one then it will be around 80 to 85% efficient; not too bad given the low price of these things.

I agree about the mechanical decoupling advantages, amongst other things it allows the incorporation of features like constant pedal rate, variable prop rate, with some fairly simple controls. Those who cycle a lot seem to prefer a near-constant cadence, so I assume this has some physiological efficiency advantage.

Jeremy

cschaffh

07-08-2011, 11:45 AM

Pedal Powered designers,

I learned a lot from hpb forums and its various predecessors and built my first boat in 2003. I've been off the radar for a while, but I am now building a new boat, based largely on Rick W's latest design. I'm partial to stitch and glue building, and I have posted some progress online. Perhaps I can pay it forward for those interested in this technique. It's been great following the latest developments. I'll update regularly and hope to be finished by Sept.

pedalplusboat.blogspot.com

Cory

cschaffh

07-28-2011, 11:39 AM

Pedal Powered designers,

Hello again. I thought I would post some information on drive components since this is common to all boats, not just stitch and glue. There are lots of drive ideas in these forums, here is one more. It is a custom box similar to recent ones Rick has made. Materials were purchased on Mcmaster.com and bearings were purchased on grainger.com. I used flange bearings since I knew I would send the design to a shop that could machine the bearing bores accurately. It is a 4:1 ratio. It weighs 5.4 lbs with crank arms. It is not cheaper than the custom mitrpak boxes, but it is higher ratio and should have higher torque capability.

I won't be able to try it for a few more weeks until the boat is done, but at least the gears have been proven by other boaters.

Coach Dave

08-07-2011, 10:56 PM

That's impressive that you can pedal such a big craft so well.

One way to stiffen the shaft might be to just lay up a carbon fibre/epoxy sleeve over it. This is pretty easy to do, as you can get hollow braided sleeves woven from carbon fibre that you just slip over the existing shaft, coat with epoxy resin and then bind with either electricians insulating tape or heat-shrink sleeving to temporarily pull it tight to the shaft (once the resin has cured you can take the tape/sleeving off).

Here's a link to a supplier across your side of the pond that shows the stuff I'm talking about - I don't know if these are the best people to buy it from over there though. http://www.cstsales.com/carbon_braid.html

Carbon fibre is a fair bit stiffer than stainless steel, so my guess is that one or two layers of this stuff will significantly increase the torsional stiffness of your shaft, without making it appreciably heavier or that much bigger in diameter.

Jeremy

I've been experimenting with unidirectional carbon fiber tape to stiffen drive shafts and decided to share what I learned so others may benefit. My starting point is my original 1/4" x 96" stainless steel shaft. The first attachments shows its compliance which I measured at 4.42 Nm/rad. One way to think about that compliance is to consider how much force it takes on a pedal (170 mm crank arm length) to deliver that much torque. With my gear ratio of 4.75 that equates to 28 pounds on a pedal. That is OK when I am spinning easily at low speed but feels mushy when I try to go faster. The next column to the right is for a 3/8" x 96" pultruded fiberglass rod with two layers of carbon fiber spiral wrapped on it. The compliance is 6.69 which is 42 pounds force on a pedal. The fiberglass rod is 0.377" in diameter which increased to 0.488" with the 2 layers of CF and epoxy. I wasn't satisfied with that so I added 4 more CF layers (see the last column) on top of the first 2 layers (6 layers total). That boosted the compliance to 19.90 which is 125 pounds force on a pedal or a factor of 4.5x my original drive shaft. The diameter of the drive shaft is now 0.642".

The second attachment is a diagram of the drive shaft with 2 CF layers on it. I used unidirectional 11 oz./yd. CF tape for these layers. For my first attempt I bought 3" wide tape thinking I would slit it to the width I needed for each layer. This tape has polyester fill thread securing the 12k tows. Once I slit the tape to the desired width the 12k tows were loose making it really hard to work with when I wrapped it around the FG rod. I wound 3 layers on the FG rod (first layer at +45, second at -45, third layer at +45 degrees). This resulted in a lumpy mess! I didn't bother with epoxy - I pulled all the CF off and decided to start over again.

Second attempt. I bought 1" wide tape, did not slit it, and wrapped two layers onto the FG rod. What I liked about this approach is the improved dimensional stability - no individual tows that I had to work with. What I didn't like - when you are working with a fixed width tape the angle of the spiral wrap turns out to be whatever it takes to avoids gaps or overlaps as you are winding a layer - not necessarily 45 degrees. The other thing I noticed is that the thickness & width of tape varies due to the tows not being firmly bound together. This yielded a stiffer drive shaft but was still not enough of a change.

Third attempt. I decided to add more layers. This time I bought 9 oz./yd. unidirectional CF tape. This tape was 5" wide and has thin strips of hot melt glue on one side that bind the tows together. I was able to slit this tape to the width I needed for each layer to be at +/-45 degrees without the tows coming apart. The thickness and width of the tape seemed to have less variation while I was winding a layer than other style of tape that used polyester fill thread.

Wetting the CF: I wound the first 2 layers, applied epoxy, put on heat shrink tubing, shrunk the tubing with a heat gun, then cured the epoxy in the Florida sunshine - we've been averaging high nineties every day! For layers 3 - 6 I wound all 4 of them then applied epoxy. I use thin epoxy that seemed to wet through 4 layers at a time without any problem. Then came the heat shrink tubing and curing in the Florida sun. A more conservative approach would be to wind one layer then epoxy then anothe layer, more epoxy, etc. Or you could work with two layers at a time - lots of room to optimize and perfect the process. If other folks try CF wrapped shafts let me know what you did and how it turned out.

Jeremy Harris

08-08-2011, 02:00 AM

Coach Dave

08-08-2011, 08:14 AM

I considered using the carbon fiber sleeves instead of the winding the unidirectional tape. My intuition is that the over/under weave of the CF sleeves would make it less stiff than winding consecutive layers of unidirectional tape alternating from +45 to -45 degrees. That is the same concept of why biaxial material is stronger than woven material. The sleeves cost about twice as much as the unidirectional tape. I didn't try using the sleeves but I think you are right - they probably would be quicker to install. Since my primary goal for the CF was to improve the torsional stiffness of the drive shaft I went with the spiral wound approach. That said, I am interested if anyone has used the CF sleeves and what torsional stiffness they measured for this type of application.

portacruise

08-08-2011, 09:27 AM

Here is a more or less commercial version of the shaft you are describing, but hollow: http://www.graphitestore.com/itemDetails.asp?item_id=1372&prd_id=99&cat_id=34&curPage=1

The manufacturer may have longer lengths and diameters or perhaps they can be spliced with metal since the whole tube doesn't always need to be flex' depending drive design. Maybe they can supply specks if contacted directly to see if that is about what you need. Rick, who generally likes to hand make just about all his parts, had someone make him a CF drive shaft to his specks, so the self make process may be challenging....

I picked up a CF shaft golf driver at Goodwill for $2 and the tapered hollow shaft is very stiff, extremely light and torsionally compliant for lower power ratings that I use in my gadgets, at about 50 watts. I suspect something like that would hold up at much higher demands but don't know the formula they use or have any measurements to prove it....

Porta

I considered using the carbon fiber sleeves instead of the winding the unidirectional tape. My intuition is that the over/under weave of the CF sleeves would make it less stiff than winding consecutive layers of unidirectional tape alternating from +45 to -45 degrees. That is the same concept of why biaxial material is stronger than woven material. The sleeves cost about twice as much as the unidirectional tape. I didn't try using the sleeves but I think you are right - they probably would be quicker to install. Since my primary goal for the CF was to improve the torsional stiffness of the drive shaft I went with the spiral wound approach. That said, I am interested if anyone has used the CF sleeves and what torsional stiffness they measured for this type of application.

portacruise

08-08-2011, 09:46 AM

I really like that box because of its light weight. Here is another thing that is being modified by some pedallers which is compact http://www.traditionalwoodworker.com/Heavy-Duty-Hand-Drill-with-Chest-Plate-1_2/productinfo/500-0344/ There are other even smaller versions but maybe not hold up to racing stresses though...

Porta

Pedal Powered designers,

Hello again. I thought I would post some information on drive components since this is common to all boats, not just stitch and glue. There are lots of drive ideas in these forums, here is one more. It is a custom box similar to recent ones Rick has made. Materials were purchased on Mcmaster.com and bearings were purchased on grainger.com. I used flange bearings since I knew I would send the design to a shop that could machine the bearing bores accurately. It is a 4:1 ratio. It weighs 5.4 lbs with crank arms. It is not cheaper than the custom mitrpak boxes, but it is higher ratio and should have higher torque capability.

I won't be able to try it for a few more weeks until the boat is done, but at least the gears have been proven by other boaters.

Coach Dave

08-08-2011, 10:33 AM

Here is a more or less commercial version of the shaft you are describing, but hollow: http://www.graphitestore.com/itemDetails.asp?item_id=1372&prd_id=99&cat_id=34&curPage=1

The manufacturer may have longer lengths and diameters or perhaps they can be spliced with metal since the whole tube doesn't always need to be flex' depending drive design. Maybe they can supply specks if contacted directly to see if that is about what you need. Rick, who generally likes to hand make just about all his parts, had someone make him a CF drive shaft to his specks, so the self make process may be challenging....

I picked up a CF shaft golf driver at Goodwill for $2 and the tapered hollow shaft is very stiff, extremely light and torsionally compliant for lower power ratings that I use in my gadgets, at about 50 watts. I suspect something like that would hold up at much higher demands but don't know the formula they use or have any measurements to prove it....

Porta

Rick did have a CF drive shaft built for him. He measured it at 16 Nm/rad which is not as stiff as he wanted. The link you provided said most of the CF is oriented longitudinally which does little for torsional stiffness. The torsional stiffness is proportional to the 4th power of the shaft radius so a 1/2" shaft has a 16x advantage over a 1/4" shaft. What you really need for torsional stiffness is spiral wraps at +/- 45 degrees. The link did say they use pre-preg CF which would be an improvement over my handmade process. I think the ideal process would be machine tightly wound unidirectional pre-preg CF over an aluminum mandrel at alternating +/-45 degrees then cured in an oven. My 8' drive shaft doesn't fit in my oven so I rely on Florida sunshine!

Arlo1

08-13-2011, 01:00 PM

Did you try the hollow CF braid that's made for this job? I've not tried it, but have hear good reports about it being a very easy way to make CF tubes and spars. It has the advantage of a double approximately 45 deg wrap, provided the right size of braid is chosen.

I'd guess that using hollow braid would be a lot easier than using uni tape for this job.

Jeremy

Jeremy we realy miss you on E.S. are you alright? Did you fix your internet problem? I tried emailing you but your acount is set up not to alow it. Hope to get you back soon.

Jeremy Harris

08-16-2011, 03:47 PM

Jeremy we realy miss you on E.S. are you alright? Did you fix your internet problem? I tried emailing you but your acount is set up not to alow it. Hope to get you back soon.

Hi Arlo,

Thanks, all's OK, I've just seen this, logged in to ES and posted.

Jeremy

joco

09-18-2011, 01:25 AM

hi guys.

right now i have few kayaks.

one off them a natives ultimate 14.5 is ropel by a bass yak kit. witch i love.

here it is

http://i287.photobucket.com/albums/ll158/paddlefishermans/IMG_8601-1.jpg

the prob its NOT self propel..not allowed in self propel fishing derbies.

many people there have hobies pedel yaks and many paddling.

me i would love to keep my kit on mine..but turn it into self human powerd.

reading the coach dave response it got me thinking.

is there is a simple way to keep it all..but make that motor go..wit my powerd.....would love to keep my hands free.most off time taugh...like an hobies.

its a little project i would love to do. this winter.

thanks for all help.

joco

joco

09-18-2011, 01:28 AM

if somebody use a little pedal systeme to charge a 12volt batteries is this SELF PROPEL..?

i want to make it simple and small.

joco

Coach Dave

09-19-2011, 08:27 AM

Joco,

I think a pedal powered generator could work for your application. To meet the self propelled criteria you should eliminate the battery and connect the generator directly to your existing motor. You will still have the ability to paddle when your hands aren't on fishing equipment. You could try using your existing seat to see if that is comfortable while pedaling. I found that for hours of sustained hard pedaling recumbant bicycle style seats are quite comfortable. However for intermittent easy pedaling to maneuver while you are fishing your current seat may be fine.

Dave

GMR

09-23-2011, 06:57 AM

I57

09-29-2011, 03:01 AM

Cat vs mono, this has been debated many times not only on this website but many others. The stabilised monohull is faster but which one, cat or mono goes back to what you want to use the boat for. Mono for speed or cat for stability. As far as wave height goes you will get wet with either boat. I'm probaly biased as my boat is a stabilised monohull with the outriggers set to just skim the surface. Having the outriggers tapering out to a larger section higher up will give you more chance of surviving a knockdown. Giving yourself room to paddle is a good idea, long slender outriggers (1/2 to 3/4 of boat length) work better in rough water, having support poles at each end keeps them solidly in position and not pitching up and down. One other thing to consider is windage, a boat that is narrow and deep will slice the waves well but will be hard to turn. Keep the above water side section low and angled, flat high sides will make the boat hard to handle when the wind is strong. Hope all of this helps.

Ian

GMR

09-29-2011, 05:58 AM

Thanks Ian,
I am thinking I may cover both types of boats by building two hulls that can be either used as two separate monohulls equipped with outriggers, or be attached to a frame and used as a cat. Sounds like the outriggers should be longer than I had imagined and I should look at the hull displacement a little more carefully. I had not really given the windage issue enough consideration and was planning vertical plywood sides, mostly because of ease of construction. I will either change the profile above the water line or reduce the deck height to minimize that effect. Not having enough room to paddle is one criticism I have seen of the Hobie Aventure Island as well.
I appreciate your input Ian and I am amazed at all the great ideas people have put forward to this site. I plan to set up a site to detail the construction and testing of this project, what ever it turns out to be!

Glen

GMR

09-29-2011, 10:37 AM

Hello again Ian,

Are there pictures of your boat(s) on the net? I'm wondering what sort of hull configuration you used, especially the beam.......and if you achieved the level of performance you were expecting/hoping for. Thanks

Glen

I57

09-29-2011, 09:59 PM

Glen
If you trawl through this thread I have a few pics up of my boats and the trials and errors I've had. Pics are of my latest boat which I have modified a few times, the pic boat4 is the latest. Boat specs are length 5metres beam 2.2 metres, total weight including gearbox is 31kg. The 5 metre length is because its the biggest I can fit in my garage, the boat unbolts for transport on the car roofrack. The boat is designed for lakes and rivers but have been on the bay on a calm day. Will be away travelling in the next few weeks and will have net access occasionally, good luck with your boat.

Ian

Coach Dave

10-22-2011, 08:11 PM

I had my heart set on building a pedal powered cat this winter until I saw a posting from several years ago where someone (Rick maybe?) said that a cat required 39% more power to reach the same speed as an equivelent stabilized mono-hull. I was going to make two hulls 18 feet long and 8 inches wide with plywood sides and rounded strip bottoms. Cross section would be consitent for the center 8 feet and have sharp bow and stern. Hull separation to be 6 feet center to center. Drive system would be bicycle components to a sturdy angle drive and then the long flex shaft to the rear to an airplane prop to start with.
This will be used on sheltered ocean areas where conditions can range from flat calm to 2 foot wind chop, likely in the same trip. I won't be racing but like my recumbent lowracer, I do like to get where I am going at the best pace possible given the conditions.....
Would I be correct in thinking that the difference in potential performance of these two types of boats would get closer as the waves get higher? I am wondering also if a useful compromise would be a mono-hull with outriggers designed for low drag when they touch flat or calm water, but with increased displacement up higher that would keep the boat upright as the chop increases. Most people seem have the outriggers biased more towards the stern...I can see that this makes more room if you need to paddle, but is there a handling (seaworthy-ness) advantage to this as well?
Thanks, Glen

Glen,

Which is better - an monohull or a cat - Like Ian said, it all depends on how you want to ust the boat. My boat started out as a mono with a single outrigger 8' out from the main hull. http://www.youtube.com/watch?NR=1&v=uAUb47sUdjw That configuration worked nicely and allowed me to position the main hull close to a dock so it is easy for passengers to load/unload. The outrigger has enough bouyancy that I can stand on it without it submerging. The stability comes at a price. The main disadvantage is drag - the additional wetted surface area means more friction. Because the drag is 8' from the center of the main hull it exerts a torque that tends to turn the boat. I went about 65 miles with the boat in that configuration on various boating/camping trips before switching to a stabilized monohull. http://www.youtube.com/watch?v=c_l86SA3i5E I put a video on YouTube because the file is too big for this forum. The boat is very stable. There are 4 of us in the boat plus our food and camping gear. My son is standing up as we get underway and the boat is not rocking. I used a 1/4" stainless steel drive shaft in the first video. The second video shows the carbon fiber drive shaft I made to deliver more power to the prop. The stabilizers are 6" wide and 24' long compared to the main hull which is 2' wide and 28' long. There are two key aspects to the dual stabilizers: 1) the weight of one stabilizer is balanced by the other stabilizer and 2) they are trimmed so that only a small part of the aft section touches in flat water. You can see from the second video that the fore section is up above the water. I have a solo kayak bungeed to each stabilizer to haul them along. When we get to a place that we want to explore in the solo kayaks we launch them from the mother ship like this next video shows. http://www.youtube.com/watch?v=oxwTNn_7OKk You can see how high the fore end of the stabilizers are riding above the water. You can also see how much wake there is from a small recreational kayak carrying one person compared to the mother ship. Toward the end of the video you can see the field expedient repair - I tied 550 cord around the stabilizer because the diagonal strut gave way. Here is a side view (Jr at the pedals) showing how the boat is trimmed with two people and all our camping gear on board. The weight is shifted aft to keep a nose up attitude. I also attached a view facing fore (heading out on a beautiful lake) that shows the trim with 4 people on board. This next photo (no ripple at Mill Creek Falls) shows there is no ripple from the fore end of the stabilzer in flat water. The next photo (outrigger up) shows the same thing. Since I use the boat for touring I added fore and aft holds (Retrieving Lunch from Forward Hold). They are big enough for tents, sleeping bag, small coolers, water bottles, etc.

Dave

Coach Dave

10-22-2011, 09:58 PM

How long does a drive unit last? Bicycle chains, chain rings, cranks, sprockets, etc. last for 1000s of miles when they are properly maintained. How about your pedal powered boat drive train - can it last 1000 miles? I don't know if mine can so I always take paddles along with us when we head out on the water. We went 28 miles on Lake Jocassee, South Carolina at the beginning of October - the trip that my drive train crossed the 100 mile mark. The picture in my post #1108 on page 74 shows bicycle components (partial frame, bottom bracket, chain ring, cranks, pedals, chain, sprocket) driving a string trimmer gear head. My current gear ratio is 4.75 rotations of an APC20015E prop to one rotation of the cranks. That gear ratio works OK on my 28' boat with 2 to 9 people onboard. So cruising around for 100 miles has worked OK. What about taking it up a notch and going for an all out sprint? We found out when we were 2 miles away from the dock at Lake Jocassee. Check out the "twisted shaft" picture. The twisted piece of metal at the bottom of the picture is the end of a 3/8" stainless steel threaded rod that I ground down to 0.182" square to connect my drive shaft to the string trimmer gear head. During a sprint there was enough torque on the shaft that it exceeded the yield strength of the shaft where it was tapered. At the top of the picture is a Grade 8 3/8" bolt. At the middle of the picture is my improvement - I ground down a Grade 8 bolt to make a tapered section that fits into the coupler in the right side of the picture. I found out that I could go slightly larger (0.205") by angling the corners slightly. The larger area and the higher yield strength steel should be able to handle 5x the torque. I never had that problem before with a 1/4" stainless steel drive shaft because that shaft was too springy. Now that I have a carbon fiber shaft I can deliver way more power to the prop. I am working on other improvements also. I attached a picture "Driveshaft at 33 degrees" showing a severe angle that the carbon fiber shaft makes as it leave the string trimmer gear head. I put it at that angle so the sprocker could be aligned with the bicycle chain ring. When I was using the 1/4" stainless steel shaft it was very flimsy - compliant enough to align with the flow once I got moving. Now with the stiffer carbon fiber shaft I am getting a sidewise force from the shaft deflecting water and a thrust vector since the prop doesn't completely align with with flow. I repositioned the string trimmer gear head to reduce the 33 degrees to 10 degrees and added an idler puller to help twist the chain. The picture "beached rudder & prop" is taken in clear enough water to be able to see the rudder slightly kicked back from hitting the bottom and the prop resting on the bottom. The downward angle is too severe for the carbon fiber shaft. With the 1/4" stainless steel shaft I had to have a strut to keep the shaft down. When I pedal hard the prop would ride up near the surface, ventilate, and I would lose thrust. With the carbon fiber shaft I let the prop be free swimming and it doesn't ride up no matter how hard I pedal. So I reduced the downward angle also. The recumbent seat is also visible in that picture. It is much more comfortable on a long trip than my initial seat shown in post #1108. I like to hang my hydration pack on the back of the seat so I can sip water whenever needed. I attached another picture "rudder recumbent seat drive unit) that gives a closer view of the seat and the rudder fully raised.

The string trimmer gear head is still working after 100 miles. It was free and already used when I got it off an old broken string trimmer. So I wonder how long it will last. How about angle grinder gears? Does anyone have experience with their longevity in this application? I am looking for a pedal powered drive train that is low price, efficient, light weight, keeps going and going and going . . . In other words it should be like a bicycle - a little bit of maintenance now and then, some adjustments when needed, other than a few flats perhaps - nothing major should wear out or break down for a few 1000 miles.

Dave

portacruise

10-26-2011, 11:20 AM

Coach:

Thanks for your update and pics! I had some questions/comments on your setup- see the main body of your message.

How long does a drive unit last? Bicycle chains, chain rings, cranks, sprockets, etc. last for 1000s of miles when they are properly maintained. How about your pedal powered boat drive train - can it last 1000 miles?

It should last 1000 mi. IF if the setup is entirely slightly heavier bike chain, like the enclosed oil bath twisted drive produced by Bob Stuart many years ago. http://microship.com/bobstuart/spinfin.html

I don't know if mine can so I always take paddles along with us when we head out on the water. We went 28 miles on Lake Jocassee, South Carolina at the beginning of October - the trip that my drive train crossed the 100 mile mark. The picture in my post #1108 on page 74 shows bicycle components (partial frame, bottom bracket, chain ring, cranks, pedals, chain, sprocket) driving a string trimmer gear head. My current gear ratio is 4.75 rotations of an APC20015E prop to one rotation of the cranks. That gear ratio works OK on my 28' boat with 2 to 9 people onboard. So cruising around for 100 miles has worked OK. What about taking it up a notch and going for an all out sprint? We found out when we were 2 miles away from the dock at Lake Jocassee. Check out the "twisted shaft" picture. The twisted piece of metal at the bottom of the picture is the end of a 3/8" stainless steel threaded rod that I ground down to 0.182" square to connect my drive shaft to the string trimmer gear head. During a sprint there was enough torque on the shaft that it exceeded the yield strength of the shaft where it was tapered. At the top of the picture is a Grade 8 3/8" bolt. At the middle of the picture is my improvement - I ground down a Grade 8 bolt to make a tapered section that fits into the coupler in the right side of the picture. I found out that I could go slightly larger (0.205") by angling the corners slightly. The larger area and the higher yield strength steel should be able to handle 5x the torque. I never had that problem before with a 1/4" stainless steel drive shaft because that shaft was too springy.

I am surprised that 1/4" SS didn't break, even without sprinting. If your design permits, you can use a two piece rigid tube/solid spring flexible steel shaft that is 1/4" electrician's drill shaft at the bottom and it would be considerably stronger.

Now that I have a carbon fiber shaft I can deliver way more power to the prop.

Where did you find the carbon fiber shaft (solid or tube?) and what diameter is it? I think you were making a carbon one, last I heard, so what procedure did you use? I am surprised that the APC electric prop has not broken. Rick W. seemed to think that even regular duty gas APC props lost a lot of efficiency because of bending and distortion.

I am working on other improvements also. I attached a picture "Driveshaft at 33 degrees" showing a severe angle that the carbon fiber shaft makes as it leave the string trimmer gear head. I put it at that angle so the sprocker could be aligned with the bicycle chain ring. When I was using the 1/4" stainless steel shaft it was very flimsy - compliant enough to align with the flow once I got moving. Now with the stiffer carbon fiber shaft I am getting a sidewise force from the shaft deflecting water and a thrust vector since the prop doesn't completely align with with flow. I repositioned the string trimmer gear head to reduce the 33 degrees to 10 degrees and added an idler puller to help twist the chain. The picture "beached rudder & prop" is taken in clear enough water to be able to see the rudder slightly kicked back from hitting the bottom and the prop resting on the bottom. The downward angle is too severe for the carbon fiber shaft. With the 1/4" stainless steel shaft I had to have a strut to keep the shaft down. When I pedal hard the prop would ride up near the surface, ventilate, and I would lose thrust. With the carbon fiber shaft I let the prop be free swimming and it doesn't ride up no matter how hard I pedal. So I reduced the downward angle also. The recumbent seat is also visible in that picture. It is much more comfortable on a long trip than my initial seat shown in post #1108. I like to hang my hydration pack on the back of the seat so I can sip water whenever needed. I attached another picture "rudder recumbent seat drive unit) that gives a closer view of the seat and the rudder fully raised.

The string trimmer gear head is still working after 100 miles. It was free and already used when I got it off an old broken string trimmer. So I wonder how long it will last. How about angle grinder gears? Does anyone have experience with their longevity in this application? I am looking for a pedal powered drive train that is low price, efficient, light weight, keeps going and going and going . . . In other words it should be like a bicycle - a little bit of maintenance now and then, some adjustments when needed, other than a few flats perhaps - nothing major should wear out or break down for a few 1000 miles.

Dave

Thanks!

Porta

Coach Dave

10-26-2011, 09:56 PM

Porta: "Where did you find the carbon fiber shaft (solid or tube?) and what diameter is it? I think you were making a carbon one, last I heard, so what procedure did you use? I am surprised that the APC electric prop has not broken. Rick W. seemed to think that even regular duty gas APC props lost a lot of efficiency because of bending and distortion."

I started with a 3/8" x 96" pultruded fiberglass rod as form to wrap alternating layers of carbon fiber onto. After 6 layers of CF the outside diameter ended up at 0.642" with 19.9 Nm/Rad compliance. That is stiff enough of a drive shaft with a 4.75 to 1 ratio on a 20x15E prop to give a nice solid feel on the cranks. See the description, diagrams and measurements on page 76 post #1140. Let me know if you have questions, want to see pictures, etc.

My boat is typically loaded down with people, food, water and camping gear - usually 1000 to 1500 lbs of total displacement. The 20x15E prop seemed to work fine pushing that boat around for the last 35 miles. It has a few minor nicks and scratchs from hitting things underwater but otherwise is holding up OK. The prop cost me about $15 so I decided to give it a try. It should slip less than the 16x16 prop that I was using previously. There are also 26x15E props available but I haven't tried them. The model airplane props are not as efficient as a purpose built prop for a specific speed/RPM/load design point. I'd like to start making my own folding props to gain some efficiency and shed weeds.

Dave

Coach Dave

10-26-2011, 10:09 PM

Porta: "I am surprised that 1/4" SS didn't break, even without sprinting. If your design permits, you can use a two piece rigid tube/solid spring flexible steel shaft that is 1/4" electrician's drill shaft at the bottom and it would be considerably stronger."

I'm guessing that the 16x16 prop was slipping quite a bit and limiting the torque I could apply to the shaft. Now that the carbon fiber shaft is operational the stainless steel shaft is my backup. Paddles are a backup for my backup. :>)

Dave

portacruise

10-27-2011, 01:23 AM

Thanks, Coach Dave.

What kind of epoxy did you use and what kind of thinner did you use to get a soak through?

Porta

Porta: "Where did you find the carbon fiber shaft (solid or tube?) and what diameter is it? I think you were making a carbon one, last I heard, so what procedure did you use? I am surprised that the APC electric prop has not broken. Rick W. seemed to think that even regular duty gas APC props lost a lot of efficiency because of bending and distortion."

I started with a 3/8" x 96" pultruded fiberglass rod as form to wrap alternating layers of carbon fiber onto. After 6 layers of CF the outside diameter ended up at 0.642" with 19.9 Nm/Rad compliance. That is stiff enough of a drive shaft with a 4.75 to 1 ratio on a 20x15E prop to give a nice solid feel on the cranks. See the description, diagrams and measurements on page 76 post #1140. Let me know if you have questions, want to see pictures, etc.

My boat is typically loaded down with people, food, water and camping gear - usually 1000 to 1500 lbs of total displacement. The 20x15E prop seemed to work fine pushing that boat around for the last 35 miles. It has a few minor nicks and scratchs from hitting things underwater but otherwise is holding up OK. The prop cost me about $15 so I decided to give it a try. It should slip less than the 16x16 prop that I was using previously. There are also 26x15E props available but I haven't tried them. The model airplane props are not as efficient as a purpose built prop for a specific speed/RPM/load design point. I'd like to start making my own folding props to gain some efficiency and shed weeds.

Dave

Coach Dave

10-27-2011, 12:51 PM

Porta: "What kind of epoxy did you use and what kind of thinner did you use to get a soak through?"

I am using 635 Thin Epoxy Resin System with 2 to 1 SLOW Epoxy Hardener from http://uscomposites.com/epoxy.html I don't thin it because it is already quite thin. I am usually working with it in hot weather which makes it even thinner. Since I was wetting 4 layers of CF at once I used a metal stud as a trough, put the shaft in a corner of the stud, poured on the epoxy, worked it in with a brush, turned the shaft about 30 degrees, then repeated until it looked like the shaft was thoroughly soaked. Then I slipped on a heat shrink tube. As I heat shrunk the tube excess epoxy squirted out the end. Then I sat the shaft in the Florida sun to "bake". Once it was cured I slit and removed the heat shrink, sanded the shaft, gave it a coat of epoxy then several coats of urethane.

Dave

hpsb

11-10-2011, 10:44 AM

Hi,

I'm part of a team of mechanical engineering students from the University of Nottingham (UK) and we're attempting to design and built a human powered boat.

We're still in very early stages and I'm very grateful to all those who have posted in this forum as it has already provided us with a huge amount of advice.

I am currently looking into our options for drive systems and need to be able to justify (preferably quantify) all the design decisions made.

From what I have read so far, I am leaning toward a twisted chain arrangement, but am struggling to find any data to help me quantify losses associated with twisting the chain. Does anyone know of any sources which might be able to help me with this?

For interest, we are aiming solely for sprint speed. Our current design thinking is a catamaran driven by two riders, in recumbent position. We will have two hydrofoils, a larger one at the rear and smaller varying pitch foil toward the front. We will have a propeller attached to the rear foil so the drive system for the propeller can be enclosed within a fairing which also supports the foil. We need to try and stay within a budget of £500 for the project.

Any help or suggestions at all would be greatly appreciated,

Emily

Jeremy Harris

11-10-2011, 11:10 AM

Welcome Emily, this sounds like an interesting project. I'm not sure that anyone has accurately quantified the losses from twisted chain drives, but the general consensus seems to be that they are small, probably only slightly higher than a straight chain drive. It helps to use the smallest pitch chain that you can find, but that will still take the drive torque OK. 6mm pitch chain (a bit smaller than the number 25 stuff more common in the US) is very flexible and if it will take the tensile load then would probably be a good choice. It's readily available here in the UK from places that sell parts for robots (try Technobots, they are a good source).

I'd suggest building a simple test rig to establish the chain losses and look at the effect of different size sprockets. The general principle seems to be to keep the sprocket sizes as small as practical on the twisted part, and keep the distance between the sprockets as great as practicable to minimise twist at each link. A fairly quick and dirty experiment on the bench would give you some solid data to work with.

One thing's for sure, twisted chains are a lot cheaper than a really efficient gearbox. Cheap gearboxes tend to be a bit lossy, especially at high torque loading, whereas a chain is probably about as efficient a drive as you can get.

Tiny Turnip

11-10-2011, 12:51 PM

Hi Emily

I have (commercial, seacycle) twisted chain drives on my catamaran. Jeremy is quite right, the losses are very small, probably the smallest you are likely to get with any transmission.
I remember Rick Willoughby, the author of this thread, did quote them somewhere.
The hydrofoil idea will potentially give you the highest speeds, but it will be very demanding of your design, development, and in particular available power (how fit and strong your 'engines' are - I'd guess you would need a couple of competitive club level cyclists at least) and how light you can build.

For a non foiling design, Rick has clearly demonstrated that a long (7 metreish ) monohull with outriggers is likely to be the fastest solution. The cat layout may be an easier, more stable platform with which to foil, but if you don't have the power to weight ratio to get out of the water, then the outriggered mono is a winner. There is a huge amount of detail on all this on this thread, but wading through it is not for the faint hearted. There's many here better qualified than me to detail the reasons the mono is better than the cat, but I'll have a go if no one else pipes up!

The fastest pedal powered boat was Decavitator, with an air prop on foils - I expect you know that. (MIT) There has also been a design with two opposing recumbent seats, can't remember if it was a foiler or not.

Incidentally, there used to be an outfit which would hire out some (rather poorly maintained) seacycle cats quite near you. I'll see if I can recall/dig out where.

Good luck!

Adrian

Tiny Turnip

11-10-2011, 03:59 PM

I did a little hunt (opening the pedal powered boats thread and using the 'search this thread' button is very helpful) plus some forum searches and found these posts:

http://www.boatdesign.net/forums/boat-design/twisted-belt-chain-drives-20535.html

http://www.boatdesign.net/forums/boat-design/pedal-powered-boats-23345-15.html#post240302

It looks like twisted chain hits about 97% efficiency, compared with 99% for straight chain.

Decavitator was Mark Drela at MIT.

I think it was these folk who used to hire seacycles, but they seem to just be advertising waterbikes now:

http://www.barrowboating.co.uk/small_crafts.php

blisspacket

11-10-2011, 07:38 PM

I'd think it a worthwhile challenge to create the formulae to evaluate hydrofoiled personpower vs. displacement personpower to achieve say 15 knots. While shop time is pure bliss, the engineering discipline demands numbers crunched. Tom Speer, Washington state aeronautical engineer, has messed with foiled cats, I believe. worth searching out.

portacruise

11-10-2011, 09:44 PM

Emily:
Bob Stuart produced the spinfin a twisted chain drive running in an oil bath for commercial use sometime ago, but it is no longer in production. http://microship.com/bobstuart/spinfin.html You can contact Bob at the hpb website. Since you are only interested in sprint speed and are using 2 motors the chain and assembly may have to be quite rugged. Once cats are on their foils and sprinting, there shouldn't much difference from a mono. Some cats have used inflatable pontoons to lighten the load.

Hope this helps.

Porta

Coach Dave

11-11-2011, 04:59 AM

Hi Emily,

Since you are looking at the drive train to operate at sprint speed with two cyclists I'd recommend establishing a speed/time/distance goal for your project. Let's say you want to maximize the average speed on a one minute sprint. Characterize your engines on a recumbent exercise bicycle. Measure how many watts your engines (the cyclists) can sustain for 15s, 30s, 60s, 90s and 120s. You can also measure their preferred RPM range at the same time. That test will quantify the speed and torque input to the drive train so you can begin analyzing components under those operating conditions.

Consider what an "ideal" drive train would do:
1) Convert 100% of the input power to forward thrust at the design speed
2) Have zero drag
3) Has 100% reliability

At high speeds the drag on underwater appendages become a very significant factor on your overall performance. You will probably want to derive a figure of merit for your candidate drive trains that encompasses drag and efficiency. The efficiency I am talking about here is end-to-end, i.e., output power (thrust times speed) divided by input power. A free swimming flexible driveshaft with the right torsional stiffness looks like a good thing to evaluate along with your other candidates.

Dave

Submarine Tom

11-11-2011, 11:33 AM

I can tell you right now that an elite athlete trained for the task can produce up to 1/2 Hp for about a minute. What you are likely to find is a good athlete can produce 1/4 - 1/3 Hp for a couple of minutes. While your average weekend warrior about 150 watts for five minutes and 100 watts for hours.

-Tom

hpsb

11-11-2011, 11:59 AM

Thank you all for your quick replies and warm welcome.

Jeremy, I will definitely try and take your advice in terms of some simple tests, there seems to be a definite disadvantage when you start twisting chains since none of the manufacturers data expects you to! And thank you for the Technobots recommendation.

We had a meeting today with a man who might be able to supply us with a canoe hull for a very good price, which would be well suited to having pontoons fitted, meaning the cat design may well take a backseat.

We're setting our aims high and hoping to get up to world record speed over a 100m flying start sprint (the decavitator and youtube have been very useful sources so far). We'll hopefully be able to persuade a few members of the university cycle team to act as our engines but will also be designing so that we (reasonably fit 20/21 years olds) can get it up onto the foils. Expectations may well have to be adjusted along the way, it's going to be a steep learning curve!

I've had a look at the SpinFin, it definitely gives me hope that a twisted chain could work, and I hope we can come up with a name as fantastic as the Lambordinghy!

I know it has been mentioned in another thread but does anyone have any experience in using a belt drive? I've come across them used in HPBs, but only at low speeds and loads.

The main reason I was initially swayed toward a twisted chain was the bulky and heavy housing that seems to be necessary in order to keep beveled gears properly aligned. I've come across one university project that built their own carbon fiber housing around their gears:
https://netfiles.uiuc.edu/ro/www/CetanHumanPoweredHydrofoilProject/cetan2_5.html

Has anyone tried this themselves or have any thoughts on our likelihood of success if we tried this (considering we are 4 students with absolutely no experience with carbon fiber)?

Again, any thoughts and advice is extremely appreciated,

Emily

upchurchmr

11-11-2011, 12:22 PM

Hpsb,

If you want to do anywhere close to a world record time you need something narrower than a canoe. I suppose the entire timed sprint will be up on foils, but you need to get up to speed and a canoe is typically heavy.

Read up on this thread, pay particular attention to "Rick"

Good luck,

Marc

Jeremy Harris

11-11-2011, 01:37 PM

I agree with Marc, you want a hull that's longer than a canoe, and lighter. Rick Willoughby undertook a number of careful experiments, developing better and faster boats with each iteration. He left this forum (a significant loss to us all) but his posts remain in this thread under the name "Guest625101138". Pretty much all he says should be read carefully, as he was methodical in his approach to getting the most from pedal power. He has a web site with some photos of his boats, here: http://www.rickwill.bigpondhosting.com/

Rick made several hulls simply using flat sheets of foam cored composite sheet, laid up on a flat surface, then cut and bonded together. This is a simple way to make a light and stiff hull.

portacruise

11-11-2011, 04:25 PM

Emily:

Since you are going for a world record and will be flying at the start with a water prop, I would think the approach will have to be adjusted. Power (trained cyclists) to weight (carbon fiber structure) ratio as well as air (Gossamer albatross) and water (minimum drag water projections -strutless props?) streamlining would come into play to a very large degree. Probably need 2 machines or a design that allows for quickly interchangable parts including fitting different pedallers. Most machines designed for a single purpose like this are as fragile as possible to save weight and durability considerations can be downgraded. The twisted chain with air prop has been proven in the decavitator as well as pedal plane records, so probably no advantage to a gearbox. Keeping down the cost may prove a challenge because of special materials with high strength to weight ratio. A small lightweight sculling hull might work better than an canoe.

Porta

Thank you all for your quick replies and warm welcome.

Jeremy, I will definitely try and take your advice in terms of some simple tests, there seems to be a definite disadvantage when you start twisting chains since none of the manufacturers data expects you to! And thank you for the Technobots recommendation.

We had a meeting today with a man who might be able to supply us with a canoe hull for a very good price, which would be well suited to having pontoons fitted, meaning the cat design may well take a backseat.

We're setting our aims high and hoping to get up to world record speed over a 100m flying start sprint (the decavitator and youtube have been very useful sources so far). We'll hopefully be able to persuade a few members of the university cycle team to act as our engines but will also be designing so that we (reasonably fit 20/21 years olds) can get it up onto the foils. Expectations may well have to be adjusted along the way, it's going to be a steep learning curve!

I've had a look at the SpinFin, it definitely gives me hope that a twisted chain could work, and I hope we can come up with a name as fantastic as the Lambordinghy!

I know it has been mentioned in another thread but does anyone have any experience in using a belt drive? I've come across them used in HPBs, but only at low speeds and loads.

The main reason I was initially swayed toward a twisted chain was the bulky and heavy housing that seems to be necessary in order to keep beveled gears properly aligned. I've come across one university project that built their own carbon fiber housing around their gears:
https://netfiles.uiuc.edu/ro/www/CetanHumanPoweredHydrofoilProject/cetan2_5.html

Has anyone tried this themselves or have any thoughts on our likelihood of success if we tried this (considering we are 4 students with absolutely no experience with carbon fiber)?

Again, any thoughts and advice is extremely appreciated,

Emily

GMR

11-16-2011, 05:39 AM

portacruise

11-16-2011, 10:21 AM

Hi, Glen.
Regarding minimum depth see post #54 on a clip I sent to Rick some years ago: http://www.boatdesign.net/forums/inboards/prop-shaft-systems-24636-4.html

Unless there is something to tangle up the prop, like seaweed, there is essentially no limitation on the shallowness with a flex shaft because of its ability to bend.

Porta

Hi Coach Dave,

I have seen photos and vids of your craft and it still amazes me that you don't have an engine hidden somewhere in there! It has changed my long term view of the sort of boats I might be able to use around here. (Nova Scotia). For now though I will stick with my plan and get a boat to play with. I have about half of one hull of my catamaran built to date and it seems to be going well. I am starting a blog and once I get a couple photos on I will supply a link. It's my first boat so there are a few small wrinkles.....but nothing serious. This won't be a feather wight but will make a great testing platform!
Now that you are using a carbon wrapped prop shaft, what do you think your minimum water depth is? I am a bit concerned about having the shaft unsupported in shallower areas since I assume that when you stop pedaling the shaft wants to straighten out. There is lots of deep water around here but it just means I will have to stay further from shore. I will be almost always in salt water so I am worried about corrosion as well. The gear and twisted chain units are attractive but I really like the idea of a shaft going over the side that I don't need to keep sealed!
1/4 stainless steel shaft sounds a little light from what I read here and I have a listing for 9/32 (303, not the best alloy) which might be better. I have lots of room on the cat so I can move components around and try to maximize the bend radius.
Glen

GMR

11-17-2011, 11:04 AM

Thanks Porta,
The idea of the prop thrashing along the bottom is certainly counter to the usual way of thinking about protecting the drive line! Is there a linear relationship between prop efficiency and angle to the flow? Is it as simple as a force vector diagram where you can separate the loads into horizontal and vertical components? Some commercial boats seem to have tried to get the shaft as horizontal as possible while still keeping the rest of the driveline inside the hull and just accept the losses.
Thanks, Glen

Tiny Turnip

11-17-2011, 11:37 AM

An image and a video of Rick's from earlier in the thread, illustrating the flexible shaft:

http://www.boatdesign.net/forums/attachments/boat-design/23439d1216205907-pedal-powered-boats-dsc06079-797573.jpg

http://www.boatdesign.net/forums/attachments/boat-design/23455d1216266495-pedal-powered-boats-v7_strutless_prop.wmv

The video shows quite clearly, how, as the boat turns, the prop moves from side to side to align with the flow.

From Rick's original post, #161 in this thread:

Mark
You may be interested in this photo:
http://boatdesign.net/forums/attachm...9&d=1216205907

That shaft operates without any support other than at the gearbox. A pushing prop is self stabilising so as soon as it starts to turn the prop just rises and aligns with flow.

This video clip shows a completely unsupported prop using an 8mm aluminium shaft:
http://www.boatdesign.net/forums/att...5&d=1216266495
I pushed the OC1 to 15kph with just that shaft. The aluminium section is 1.2m long.

I normally use a tension strut to enable going in reverse. With this and the prop beside me I can reach down and pull it up to remove fouling. Also for beaching or obstacles the prop just bounces over.

There is a balance between torsional rigidity and fatigue life. With good spring steel you can get a good compromise. I design for prop speed of 300rpm at design boat speed and 1/4" steel is just a bit thin. For sprinting I go up to 10mm spring steel and live with the extra weight to get a tolerable stress range. There is very little loss due to shaft torsional constant once you get to this thickness.

This system does result in very low appendage drag for the prop.

The other thing I have posted in earlier posts on this thread is my dipping rudders. These are only immersed when you want to turn or one just immersed enough hold a straight course.

I can provide the design data if anyone wants to have a go at a reliable curved shaft system.

Rick W.

portacruise

11-17-2011, 03:28 PM

Glen:

The inefficient aluminum prop in the film clip was from a Thai long tail which is meant to sweep the bottom like many mud motors. This would probably not work as well with one of Rick's efficient props, except maybe the folders.

I don't believe the relationship is linear between prop efficiency and angle of flow. An angled prop probably doesn't lose as much as one would think, unless it is at a very severe angle. At least the angle didn't make much difference in Greg K.'s 24 hour hpb record set with the flex shaft, about 2% compared to comparable shaft with an efficient support skeg, according to Rick. But you don't have to worry about angle with a flex shaft, as the angle always remains at the optimum.

P.

Thanks Porta,
The idea of the prop thrashing along the bottom is certainly counter to the usual way of thinking about protecting the drive line! Is there a linear relationship between prop efficiency and angle to the flow? Is it as simple as a force vector diagram where you can separate the loads into horizontal and vertical components? Some commercial boats seem to have tried to get the shaft as horizontal as possible while still keeping the rest of the driveline inside the hull and just accept the losses.
Thanks, Glen

Coach Dave

11-17-2011, 08:42 PM

Hi Coach Dave,

I have seen photos and vids of your craft and it still amazes me that you don't have an engine hidden somewhere in there! It has changed my long term view of the sort of boats I might be able to use around here. (Nova Scotia). For now though I will stick with my plan and get a boat to play with. I have about half of one hull of my catamaran built to date and it seems to be going well. I am starting a blog and once I get a couple photos on I will supply a link. It's my first boat so there are a few small wrinkles.....but nothing serious. This won't be a feather wight but will make a great testing platform!
Now that you are using a carbon wrapped prop shaft, what do you think your minimum water depth is? I am a bit concerned about having the shaft unsupported in shallower areas since I assume that when you stop pedaling the shaft wants to straighten out. There is lots of deep water around here but it just means I will have to stay further from shore. I will be almost always in salt water so I am worried about corrosion as well. The gear and twisted chain units are attractive but I really like the idea of a shaft going over the side that I don't need to keep sealed!
1/4 stainless steel shaft sounds a little light from what I read here and I have a listing for 9/32 (303, not the best alloy) which might be better. I have lots of room on the cat so I can move components around and try to maximize the bend radius.
Glen

Hi Glen,

No I don't have a hidden motor, just me pedaling. A motor would be faster but I enjoy the quiet ride. I usually have 2 to 8 other people in the boat with me and can go in the no-motor zones like a manatee santuary that is nearby. I am using a 20" diameter prop and need to keep it about 4" below the water surface to prevent it from ventilating and slipping. That makes my minimum water depth 24" although 30" or 36" gives some operating margin. If the prop occasionly hits a rock or branch it isn't a problem because the driveshaft will flex allowing the prop to move out of the way. If I see the obstacle soon enough I pick up the driveshaft to avoid striking it with the prop.

Yes, 1/4" stainless steel is too flimsy for my heavy boat. It was my starting point, served me well, and I can still take it along as a backup. The carbon fiber shaft is a big improvement and should hold up well to being immersed in salt water. I've started working on a smaller boat to be used for 1 or 2 people. It will be running at a higher gear ratio (faster shaft RPM) so it should work OK with a 5/16" stainless steel shaft. The 1/16" difference between a 1/4" shaft and a 5/16" shaft might not sound like much but it results in a shaft that has 2.44 times the torsional stiffness. I like not having any gears or seals below the water surface since those gave me problems with earlier prototypes.

Good luck with your catamaran construction.

Dave

I57

12-15-2011, 03:28 AM

Modified my boat yet again, this time have moved the outriggers to the front of the boat in an effort to reduce the drag and improve trim. On the lake last Saturday and noticed how much the bow rises the faster I go, at least 50mm in a sprint. What happens is the outriggers which were skimming the water are sinking deeper the faster I go. Have now mounted them at the bow, the weight trims the boat slightly forward but what now happens is they stay above the water the faster I go. Tested it out at the rowing course today, boat feels a bit less stable and tends to flop one side to the other, might have to lower the outriggers slightly. Didn’t take the camera so no pics yet. See how it performs the next few times out to see whether I stay with the layout or go back to the way it was.

Ian

Submarine Tom

12-15-2011, 10:41 AM

Interesting.

This is opposite to Rick's design.

-Tom

MLampi

12-15-2011, 08:44 PM

It would be interesting to hear how your boat performs with wind/waves coming from 45 degrees off the bow and when it comes from 45 degrees off the stern.

Michael Lampi

I57

12-19-2011, 04:09 AM

Had the boat at the lake on the weekend, conditions were calm with only small waves. I lowered the outriggers a bit to try and minimise the flopping from side, still does it but not as much. As much as I tried I could never achieve both outriggers out of the water, even a slight lean one way or the other was too much. Having the outriggers forward allowed me to see a lot better how much they were digging in and I could correct it before it dug in too far. The stability is just as good as with the outriggers further back, being able to better keep it on an even keel has to reduce drag and improve speed. Stick with it for now and see how it handles in rougher conditions.

Ian

Submarine Tom

12-19-2011, 10:48 AM

Would SWATH outriggers be feasible?

-Tom

ancient kayaker

12-19-2011, 09:22 PM

. . . As much as I tried I could never achieve both outriggers out of the water, even a slight lean one way or the other was too much . . .

If the CoG is above the metacenter there is no stable roll angle for the center hull.

Submarine Tom

12-20-2011, 12:28 AM

Good point. How about SWATH with foils. Roll at zero head-way would be minimal and greatly reduced once making way.

-Tom

Submarine Tom

12-20-2011, 12:36 AM

No, lets make that a SWATH foil. Providing lift (static and dynamic), roll damping (big time). So, a buoyant wing, on each side of course. Or, maybe not. Perhaps just one with vertical fins to dampen roll...

The clock on my forehead is spinning as I process... smoke is starting to come out my ears...

-Tom

upchurchmr

12-20-2011, 07:54 AM

Swath might provide roll dampening but it will not provide the initial resistance to roll, cause the buoyancy is already underwater.

A buoyant wing would work but with a huge increase in surface area when it was supporting, that is why a long skinny ama is used - less resistance a the beginning of a roll.

Vertical fins would pick up buoyancy at the cost of lots of surface area, but I can't see any roll dampening.

Tiny Turnip

12-20-2011, 09:22 AM

Interestingly, Rick W did experiment with submerged hull bouyancy, but not in a twin hull arrangement.

http://www.rickwill.bigpondhosting.com/V8.jpg

IIRC, he didn't ever expect to be able to balance his later more normal outrigger boats, just to use one outrigger or the other.

Thanks for posting your continued progress Ian, its interesting reading, viewing.

Submarine Tom

12-20-2011, 09:58 AM

Submarine Tom

12-20-2011, 12:43 PM

My mistake, I forgot SWATH meant twin hulls. I'm thinking only one with self stabilizing ailerons.

-Tom

upchurchmr

12-24-2011, 10:12 AM

Tom,

I assume you meant horizontal fins for roll damping, like an aileron on an aircraft wing. Single or double should work the same.:) A minor nit picking point on my part, sorry

Marc

Submarine Tom

12-24-2011, 11:25 AM

Marc,

No, I meant vertical as in rudder or keel. Yes, that's it, an extended keel if you will. Roll damping.

The horizontal wings on the bulb would provide roll stability via ailerons, but little to no damping.

-Tom

P Flados

01-12-2012, 09:15 PM

Rick did have a CF drive shaft built for him. He measured it at 16 Nm/rad which is not as stiff as he wanted. The link you provided said most of the CF is oriented longitudinally which does little for torsional stiffness. The torsional stiffness is proportional to the 4th power of the shaft radius so a 1/2" shaft has a 16x advantage over a 1/4" shaft. What you really need for torsional stiffness is spiral wraps at +/- 45 degrees. The link did say they use pre-preg CF which would be an improvement over my handmade process. I think the ideal process would be machine tightly wound unidirectional pre-preg CF over an aluminum mandrel at alternating +/-45 degrees then cured in an oven. My 8' drive shaft doesn't fit in my oven so I rely on Florida sunshine!

Just ran into this series of posts and saw lots of the shaft discussion over a long period of time. Carbon fiber is much better in tension than in compression. A 45 degree spiral wind in one direction on a mandrel to achieve tensile stress only would give max torsion strength and minimum torsion flex. The fact that all carbon fibers are at the same orientation that is 45 degrees to centerline greatly reduces bend stiffness. Low bend stiffness is a real plus for this application.

Given the stiffness of carbon fiber, the mandrel would be under minimal stress in service (mostly in compression due to being "squeezed" by the carbon fibers). Therefore most any material that will work during fabrication should hold up well driving the prop.

Carbon Fiber tow can be had at a good price if you are patient and shop around (I got a 5 lb spool for $80 a while back). Running a loop of tow down into a container of epoxy and then winding tightly on the mandrel can give very good fiber density. The good density from tight wound fiber applied "wet" probably comes pretty close to pre-preg for strength. Quicker but more expensive would be carbon uni "tape" wound at the same 45 degrees.

The 8' length could be a challenge. Probably need to keep the mandrel stretched tight during the winding.

portacruise

01-14-2012, 12:43 AM

Rick has gone back to a spring steel shaft in his latest boat, after experimenting carbon fiber. He has accomplished 20kph with the V15 design pictured below:

http://www.rickwill.bigpondhosting.com/V15_58.htm

His CF shafts were considerably larger diameter than the spring steel.

Some of his comments:

"The reason I can get higher speed from this boat is the low torsional compliance of the drive train. I am spinning a lower pitch prop at 7X cadence. The prop is on an 8mm diameter spring steel shaft that is only 1.4m long. The drive dynamics are much improved over my V15-6m boat with the aft mounted prop on the CF shaft.

The CF shaft has worked very well but it is so long and at 4X cadence spinning a high pitch prop the torsional compliance is noticeable above 14kph. It eventually limits top speed due to shaft recoil at the crank deadspot."

Rick sometimes posts to the hpb list.

Porta

Just ran into this series of posts and saw lots of the shaft discussion over a long period of time. Carbon fiber is much better in tension than in compression. A 45 degree spiral wind in one direction on a mandrel to achieve tensile stress only would give max torsion strength and minimum torsion flex. The fact that all carbon fibers are at the same orientation that is 45 degrees to centerline greatly reduces bend stiffness. Low bend stiffness is a real plus for this application.

Given the stiffness of carbon fiber, the mandrel would be under minimal stress in service (mostly in compression due to being "squeezed" by the carbon fibers). Therefore most any material that will work during fabrication should hold up well driving the prop.

Carbon Fiber tow can be had at a good price if you are patient and shop around (I got a 5 lb spool for $80 a while back). Running a loop of tow down into a container of epoxy and then winding tightly on the mandrel can give very good fiber density. The good density from tight wound fiber applied "wet" probably comes pretty close to pre-preg for strength. Quicker but more expensive would be carbon uni "tape" wound at the same 45 degrees.

The 8' length could be a challenge. Probably need to keep the mandrel stretched tight during the winding.

P Flados

01-14-2012, 09:43 AM

portacruise

01-14-2012, 05:03 PM

Porta,

I understand the trade offs between the options.

Looking back, I see that I did not emphasize what I was really trying to point out. A CF shaft that uses Carbon Fiber (CF ) with alternating 45 degree orientation is good for a shaft where you want good torsional strength and you WANT bending stiffness. For long - high speed shafts, bending stiffness is a plus. This improves dynamic stability which limits how fast you can spin the shaft. Some cases even warrant a layer or two of lengthwise uni fibers.

I have seen no discussion in this thread of 45 degree single orientation CF. Spiral wound steel cables with the load carrying outer layer in single orientation are used for flexible drive shafts on things like weed eaters, dremel tools, automotive speedometer cables, etc specifically to get maximum torsional strength with minimum bend stiffness.

If existing CF shafts for pedal boats have only been of the alternating orientation type, I would challenge that the existing results are not bounding and that significantly improved performance may indeed be possible.

Flados:

There was some discussion on using braided tube jackets instead of windings. Here's a commercial product along the lines http://dragonplate.com/ecart/product.asp?pID=4107&cID=79 I know this is different than winding on a mandrel.

Yes, anything is possible with carbon fiber, BUT at the expense of time and skill of the builder. Sometimes it is trial and error that is involved. Rick's CF drive shaft was custom built by a pro to Rick's mathematical specks at great $ expense and still didn't hit the target. I'm sure a perfect one could be better built on a second try. But it is faster, simpler, and cheaper to use off the shelf spring steel rod that doesn't require some artistry. Of course, CF would be the only choice in weight critical applications.

Hope this helps.

Porta

spidennis

01-15-2012, 07:02 AM

Rick has just uploaded a new V15 video

http://youtu.be/RQs6YgO93RY

upchurchmr

01-15-2012, 08:55 AM

There is another video of V15 with a more extensive fairing and single aka supported amas. Just look at the other videos when you see the one above. Now (or then) painted blue.

I57

01-17-2012, 04:22 AM

Went out in rougher conditions with the forward fitted outriggers and boat performed well. Going downwind at 45 deg to the waves the boat seemed to handle better as the outriggers were digging into the waves and kept the boat stable. Going into the wind still felt ok except every time a larger wave hit it created a huge spray of water. As it was a temporary setup to see how the forward outriggers worked I had not got around to reinforcing the supports. As a result after a rest I went out again and had only gone about 100 metres when the supports snapped off resulting in a very quick dunking in the water. Fortunatley its summer here and the day was warm as well as the water was warm, dragged the various pieces back to shore and checked nothing was missing. Have now reverted to outriggers at midships and reinforced the supports.
Have now gone back to a rudder, the directional prop worked but needed a large turning circle. Gone about as far as I can with this boat, although I have said that before. The latest change was the 10th since I built it and the weight has been going up ever since. Going to build a new boat this year, Ricks V15-5m and fit it with the involute gearbox and inline shaft.

spidennis

02-05-2012, 07:34 PM

SpinFin:
I've found very little info on this:

http://microship.com/bobstuart/lambordinghy.html

http://microship.com/bobstuart/spinfin.html

It looks like a nice sleek unit and I'm looking for options in the prop variety rather than going with the mirage drive.

Anyone got any info on this? I got an email out to the guy but it's an older page so we'll see what happens.

http://microship.com/bobstuart/pix/drive%20unit.JPG

http://microship.com/bobstuart/pix/SPINFINATCD.jpg?69,160

I57

02-05-2012, 10:04 PM

spidennis

02-05-2012, 10:27 PM

Spidennis
What I've read and heard he no longer makes these units, could be wrong and you may pick one up somewhere, ebay?
I have made one of these twisted chain drives but have never used it as I haven't found a way to keep the water out of the casing. Also the one I made was bulky and heavy, need to get some very small gears for the lower part that attaches to the prop. Other option is to go with one of Rick's flexible drive shafts, minimal amont of drag in the water.

Ian

I got a reply back! but they say they're not in production, bummer. He said he'd cc his email to me to the other partner/helper that has the molds, so who knows?

The reason I liked this was because I could stick it off the main tramp area or move it as needed. I got a special requirement and it's a bit different, I'm building a folding beach cat where the hulls end up sitting side by side with only a 3' beam when folded. This is for getting up and thru narrow sections of river and streams, think Everglades Challenge. My hulls are gonna sit about 2' high, think prindle 16 hulls and the prop drive has to work in both the full expanded sailing position and also in the narrow folded tight water position.

from what I heard Rick's drive shaft doesn't last all that long? and I'd have to find a way of mounting it to fit both hull configurations. It also needs to be pulled up and out of the way, beach landings, skinny water, seaweed, etc.

MLampi

02-05-2012, 11:21 PM

The WaveWalker folks, if they are still around, make a similar drive unit, though perhaps a bit more robust than the SpinFin.

A few years ago they weren't interested in selling them separate from their boats, but who knows? Maybe now they will sell them.

Michael

portacruise

02-06-2012, 12:12 AM

Hi, SPI:

Rick's latest, folding outriggers boat addresses some of your pull up, weed and narrow/skinny water issues with the short shaft which is within a hand's reach:

http://www.rickwill.bigpondhosting.com/V15_58.htm

Maybe a quick release hex socket could used to pull out the shaft. Somewhere in his postings on this list he estimated shaft life to be considerable, is my recollection....

Porta

I got a reply back! but they say they're not in production, bummer. He said he'd cc his email to me to the other partner/helper that has the molds, so who knows?

The reason I liked this was because I could stick it off the main tramp area or move it as needed. I got a special requirement and it's a bit different, I'm building a folding beach cat where the hulls end up sitting side by side with only a 3' beam when folded. This is for getting up and thru narrow sections of river and streams, think Everglades Challenge. My hulls are gonna sit about 2' high, think prindle 16 hulls and the prop drive has to work in both the full expanded sailing position and also in the narrow folded tight water position.

from what I heard Rick's drive shaft doesn't last all that long? and I'd have to find a way of mounting it to fit both hull configurations. It also needs to be pulled up and out of the way, beach landings, skinny water, seaweed, etc.

I57

02-06-2012, 12:59 AM

Spidennis
The flexible shaft can be either spring steel 8mm dia or machinable aluminium 10mm dia, both work ok. Your other issue is to get a suitable gearbox, I use a 1:3 ratio involute gearbox which keeps things simple. Otherwise a bike crank and chain connected to a 90 deg gearbox of 1:1 or 1:2 ratio. The setup on my proa allows me to pull the shaft clear of trhe water for beaching and in shallow water. Shaft life depends on how tight the curve is, the bigger the radius the longer the shaft life. If you trawl back through this forum there is quite a lot of info on flexible shafts.

Ian

spidennis

02-06-2012, 08:08 AM

Ok guys, I'm having a tough time seeing just where and how this is gonna mount up on my folding cat. In the unfolded position, If the peddles went off the front cross bar then the shaft could be nice and long to keep the stresses down. In the folded position then the foot crank might get in the way and the shaft will get sandwiched between the hulls leaving the prop where?

Or should I mount it over the side of the boat? Not between the hulls? As it still has to work in the folded position.

Plus it has to get out of the way for a 40 mile portage and such.

see this short youtube of my first model showing the folding.

lUUDkrRUAwY

spidennis

02-06-2012, 08:31 AM

Here is the spinfin mounted on the microship, this is a side mounting. Can either this type or Rick's "flying shaft" (if I can use that to describe it) be side mounted on my folding cat? or should I somehow get the prop off the back somehow, back by the rudders? but then the peddles and shaft?
http://nomadness.com/wordpress/wp-content/uploads/spinfin-retracted-300x224.jpg

portacruise

02-06-2012, 10:34 AM

SPI:

What is the advantage of the spinfin, since you can remove the flex shaft and maybe make a mobile mount for the cranks/gearbox? It does have to be stored out of water, clamped fore or aft of the platform, so it doesn't interfere with folding. Better with your model, would be a permanent mounting position at the rear cross, with the shaft running unsupported behind. But you would have to face backward while pedaling, using mirrors like skullers which may not be acceptable for your situation. You could also run the shaft off the side like with the spinfin. Maybe use some universal joints on the ends and a telescoping hex drive to connect the cranks and remote gearbox, but this is probably too complex.

That folding arrangement is pretty cool, but how many time would you use it on your race... Won't everything have to stay packed on the center section, or do you repack supplies each time?

Hope this helps.

Porta

Here is the spinfin mounted on the microship, this is a side mounting. Can either this type or Rick's "flying shaft" (if I can use that to describe it) be side mounted on my folding cat? or should I somehow get the prop off the back somehow, back by the rudders? but then the peddles and shaft?
http://nomadness.com/wordpress/wp-content/uploads/spinfin-retracted-300x224.jpg

spidennis

02-06-2012, 11:24 AM

SPI:
That folding arrangement is pretty cool, but how many time would you use it on your race... Won't everything have to stay packed on the center section, or do you repack supplies each time?

Porta

Porta,
In these "Challenges" there are numerous "Filters" to limit the size of the boats, they could be pilings, bridges, narrow waterways, etc, so folding and demounting the mast must be fairly quick. Then of course on the 40 mile portage it will be folded. There's enough times that a quick method of doing this is important, not just merely taking something apart.

As for gear? that all is gonna get stowed in the hulls with hatches from bow to stern. In the folded position I won't be able to get to some of the hatches. My "tent" will also be an enclosed fold up cockpit for bad weather, with the center part of the cockpit being a hard deck to which the folding hardware/mount is a part of.

I've studied the reasons for failed and aborted trips and watertribe DNFs and getting your gear soaked or lost is a major concern so I wanted to eliminate any chance of that happening. In my sea kayaking and canoe portaging trips I've learned a lot of what does work for me and I believe in double or triple water proof protection, and that means even if I have to portage all my gear on my head for 3 miles! ... and trust me every ounce I feel when doing that!

Presently I got a prindle 16 to use as my proof of concept boat, later I might go to an F16 class of hull or maybe A class, still looking for designs/plans for either. I'm leaning towards the shorter F16 class at 16' rather that 18' for the A class. 18 is better for sailing, 16 is better for the massive portage and I think that is gonna rule.

but back to the peddle prop drive, yeah I thought of sitting backwards and that wouldn't be my first choice. I need to shape my model#2 a bit and play around with that some. It is a scale model 1" to 1' to help give me scope. It also has better details on the folding operation to see just how the geometries work. I will be using a bike to tow the boat on the 40 mile portage and I've been trying to think about how I can take about the bike to use in the prop drive but then to bolt it back together again for bike operation. A recumbent bike would be best for the prop drive but I hadn't tested that style of bike in the portage mode, not yet anyway.

I didn't really want to get into all these other features but they all inter relate. It really is a system and not just separate components.

other modes of non sailing mode would be rowing with oars or to scull off the back, I'll try and use them all. They all have pros/cons, just like the peddle prop. btw, wt trend seems to be the mirage drive.
zfSN8NgWao0

http://www.duckworksbbs.com/gear/scullmatix/index.htm

9mTfzZpTlMA

spidennis

02-06-2012, 11:55 AM

this was posted Jan 14th 2012
RQs6YgO93RY

and from what I gather this is Rick filming?
I caught a glimpse of his orange v15 5.8
this is posted jan 21st a few days later

sxAjyhSOIhs

portacruise

02-06-2012, 12:39 PM

SPI:

There's a lot on google/utube on possible drives. The friction drives off bike tires are worthless especially when wet, but there was a commercial system out of Oz sometime back that took the pedal chain directly to the prop gear box. Also maybe a 2 blade air prop bike conversion might be the way to go- easier to store, lighter/no weeds/shallow water issues. There are some bikes that store compactly, Google bike Friday. Some misc. clips:

http://www.youtube.com/watch?v=ijZ2QXA-5DA

http://www.youtube.com/watch?v=ymiQbyN1z3o&feature=related

That's a lot of weight to portage 40 miles!

Porta

Porta,
In these "Challenges" there are numerous "Filters" to limit the size of the boats, they could be pilings, bridges, narrow waterways, etc, so folding and demounting the mast must be fairly quick. Then of course on the 40 mile portage it will be folded. There's enough times that a quick method of doing this is important, not just merely taking something apart.

As for gear? that all is gonna get stowed in the hulls with hatches from bow to stern. In the folded position I won't be able to get to some of the hatches. My "tent" will also be an enclosed fold up cockpit for bad weather, with the center part of the cockpit being a hard deck to which the folding hardware/mount is a part of.

I've studied the reasons for failed and aborted trips and watertribe DNFs and getting your gear soaked or lost is a major concern so I wanted to eliminate any chance of that happening. In my sea kayaking and canoe portaging trips I've learned a lot of what does work for me and I believe in double or triple water proof protection, and that means even if I have to portage all my gear on my head for 3 miles! ... and trust me every ounce I feel when doing that!

Presently I got a prindle 16 to use as my proof of concept boat, later I might go to an F16 class of hull or maybe A class, still looking for designs/plans for either. I'm leaning towards the shorter F16 class at 16' rather that 18' for the A class. 18 is better for sailing, 16 is better for the massive portage and I think that is gonna rule.

but back to the peddle prop drive, yeah I thought of sitting backwards and that wouldn't be my first choice. I need to shape my model#2 a bit and play around with that some. It is a scale model 1" to 1' to help give me scope. It also has better details on the folding operation to see just how the geometries work. I will be using a bike to tow the boat on the 40 mile portage and I've been trying to think about how I can take about the bike to use in the prop drive but then to bolt it back together again for bike operation. A recumbent bike would be best for the prop drive but I hadn't tested that style of bike in the portage mode, not yet anyway.

I didn't really want to get into all these other features but they all inter relate. It really is a system and not just separate components.

other modes of non sailing mode would be rowing with oars or to scull off the back, I'll try and use them all. They all have pros/cons, just like the peddle prop. btw, wt trend seems to be the mirage drive.
zfSN8NgWao0

http://www.duckworksbbs.com/gear/scullmatix/index.htm

9mTfzZpTlMA

Tiny Turnip

02-06-2012, 04:47 PM

Spidennis: I use a pair of reconditioned seacycle drives on my boat. I'll happily talk through what I see as the pros and cons of these units, if that's of help.
It may be worth a browse of the canoe sailing forums for thoughts on portage.

Adrian

spidennis

02-06-2012, 05:43 PM

Adrian,
Please! I'd love to hear your thoughts about your boat and it's drive system. I've been thru the whole thread as it progressed but will be going back thru it again to refresh my brain. It was YOUR boat that inspired me to this type of drive setup as I thought it could adapt to my varied requirement the best.

When the boat is deployed to the full open position almost any system could fit and operate, it's the folded position I think that is causing me problems with mounting and operation.

and I only made reference to the canoe trips for the water proofing, I don't ever plan to use a peddle prop drive, or sail or anything other than a paddle and presently use double blades with this boat but will try out a single this summer. These trips are a whole'nother animal! and I get great satisfaction out of this physical feat of varied travel.
http://www.sandslave.com/bogriverfallsportage.jpg

pics always help to visualize:
http://www.sandslave.com/badkitty/unfoldedVSfolded.jpg

upchurchmr

02-06-2012, 07:11 PM

I57
Farther back in the thread I suggested you might try a small bow rudder. Rick said it would tip you the wrong way and it seemed to drop there. If the bow rudder was shorter than the rudder it might not be able to twist the boat but still give you some more turning force. Since you are about to abandon the current boat, it might not be such an issue to try. I.E., nothing really lost. You get the changes you have made done so quick this might not be a big investment in time. Just another uninvited suggestion. Good luck.

Went out in rougher conditions with the forward fitted outriggers and boat performed well. Going downwind at 45 deg to the waves the boat seemed to handle better as the outriggers were digging into the waves and kept the boat stable. Going into the wind still felt ok except every time a larger wave hit it created a huge spray of water. As it was a temporary setup to see how the forward outriggers worked I had not got around to reinforcing the supports. As a result after a rest I went out again and had only gone about 100 metres when the supports snapped off resulting in a very quick dunking in the water. Fortunatley its summer here and the day was warm as well as the water was warm, dragged the various pieces back to shore and checked nothing was missing. Have now reverted to outriggers at midships and reinforced the supports.
Have now gone back to a rudder, the directional prop worked but needed a large turning circle. Gone about as far as I can with this boat, although I have said that before. The latest change was the 10th since I built it and the weight has been going up ever since. Going to build a new boat this year, Ricks V15-5m and fit it with the involute gearbox and inline shaft.

spidennis

02-06-2012, 08:46 PM

I57

02-07-2012, 03:06 PM

The bow rudder is one mod I haven't tried, would be interesting to try it. Have now gone back to a rudder and done away with the directional prop. Turning is much better but I slow up on turns more compared to the directional prop. The technique I used was to lean into the turn and dig in the outrigger, not having a rudder the boat didn't lose a lot of speed but had a big turning circle. Reason I went away from the directional prop was the extra stress it was putting on the flexible shaft and difficult to manouver in tight spots.
Have now started building a new boat, Ricks V15 design. Fitting it with the involute gearbox and inline shaft, lighter and faster than my current one.

Ian

spidennis

02-07-2012, 04:26 PM

I remember some sort of kayak-ish craft on foils with a front rudder and it carved up the water like crazy! I should look for that later when I got some time tonight ..... saw it on youtube.

GMR

02-08-2012, 07:45 AM

Not sure if this boat/boats will see the water this year but I am making progress. I'm building two hulls for a cat, but they will be set up to be used as singles with outriggers as well. This is my first boat since putting a plywood kayak kit together 40 years ago...a great learing experience for me! I have started a blog about this process at
http://gmrprojects.blogspot.com/
if anyone is interested. I still haven't finallized the cat frame and don't know yet how far off the water the deck should be.

Glen

spidennis

02-08-2012, 08:16 AM

Nice Glenn! ..... and I subscribed to your blog so I can stay updated.

If I can ask, just how did you strip over those v notches on the bottom of the hull? What size strips did you use?

GMR

02-08-2012, 11:14 AM

Hi Spidennis

I used 7/8 by 1/4 strips sawn from red cedar. We were using a band saw with a long guide to rip these but we still had a little trouble maintaining a constant thickness. Even though I had to taper all the strips it might have been better to use the commercial bead and cove type since the center 8 feet has a constant profile. The inconsitancies are strip thickness but also the orientation of each strip on such a small radius hull. If I did this again I would do the formers again with the CNC router but make the radius in 7/8" (or whatever strip width was) long segments instead of a smooth curve. Still be a fair bit of sanding though.....

The final strip in the center of the hull was just barely wider than the V groove but I taped popsicle sticks to the formers on the tapered ends to support these and added glue to the sides which I didn't do on any of the other ones. Even though that is one place on the hull where you really want good support, I think that will be okay as long as the epoxy penetrates well between the strips.

Cheers, Glen

spidennis

02-08-2012, 02:52 PM

Looking at the seadrive/spinfin type of unit and this Taipan F16 that I photoshopped to get a better look at what's what I think I see an option for this drive.

Note the tramp and where it sits in relation to the rest of the boat, if from there it folded forward using my system then the tramp/platform would nearly be at the very bow, and with the seadrive mounted like Adrian's boat I could clear both bows while in the folded position and I'd not have to move anything in the way of the prop drive system.

I'll have to work up my second model to reflect these ideas and see if the geometries work out.

http://www.sandslave.com/badkitty/Taipan_F16_badkitty2.jpg

http://www.sandslave.com/badkitty/unfoldedVSfolded.jpg

so this is close to what I want "Bad Kitty" to look like, peddle up front, tent on center platform, and that would either be in the expand OR folded position. For the EC (Everglades Challenge) I plan on doing the "Nightmare" thru a very tight and skinny waterway and might have to wait for the tides to change inwhich case I'll just camp in the folded position till the water comes back in. On the Suawanne or St. Mary, or on the portage I can sleep the same way while folded up, if need be, and the prop drive is out of the way.

I'm liking how this seadrive system is panning out ....... but will also come up with a flying shaft system as well and then choose which direction to go.

http://www.sandslave.com/badkitty/Clems-seacycle-tent-middle2.jpg

spidennis

02-09-2012, 11:03 AM

After fussing around with model #2 I see that the now extended length platform of 8' still isn't long enough to get close enough to the bow to set in the seadrive/spinfin.

I could though not fold the boat all the way to some thing close to folded but not all the way, then I could run the seadrive but if that were the case then I could also run the flying shaft type as well?

C7eOkMzuXiM

joco

02-13-2012, 03:36 PM

those natives propel sher look like a spinfin and so on.

http://www.nativewatercraft.com/boat.cfm?id=13

i did try them..they good...love the going forword and backword compare to an hobi that can not go backward..plus the speed was good to...and its easy to instal and take out etc.
joco

Scheny

02-14-2012, 04:29 AM

Hi guys!

I am currently inventing a new approach for human powered boating. My idea was not have the longest and sleekest boat, but instead to have the smallest/lightest and removing the drag of the wave.

You say thats impossible? No, in fact, it creates a small wave and surfs on it, reusing its energy this way.

Key benefits:

Stable monohull
Light weight
Easy to build
+50% speed at same weight/dimension
-35% energy consumption at the same speed

The prototype will be start building in March. Information can be found under:
http://www.openwaterbike.com/projects/the-open-wavewaterbike-project/the-wave-interference-hull

Data:
Length: 2.6m
Beam: 0.75m
Draft: 0.35m
Weight: 20kg
Displacement: 105kg
Cruise speed: 12km/h (6.5kt)

Well, it won´t be the fastest, but at this values maybe the most popular.

I am not a company and I do the research in my free time. After finishing the prototype, I will start to sell plans, but if there is enough demand, I can let it produce too.

If you are interested, contact me.
Sincerely, Andreas

http://www.waveless.at/images/phocagallery/Zero/thumbs/phoca_thumb_l_wavebike_render2.pnghttp://www.waveless.at/images/phocagallery/Zero/thumbs/phoca_thumb_l_wavebike_render4.png

upchurchmr

02-14-2012, 06:46 AM

Good luck.

What does it mean
+50% speed at the same weight/dimension? You started off comparing to a "long, sleek" boat. So are you talking about the same weight or the same length?

spidennis

02-14-2012, 06:49 AM

Andreas,
it sounds interesting .....
but could you resize that image file please?

Scheny

02-14-2012, 08:13 AM

Good luck.

What does it mean
+50% speed at the same weight/dimension? You started off comparing to a "long, sleek" boat. So are you talking about the same weight or the same length?

The drawback of this hullform (displacement glider invented by D.I. Theodor Eder) is, that the effect of wave interference can only be achieved while maintaining the dimensions. So for constructing a 105kg displacement boat, the length is only 2.6 meters, lowering the hull speed normally to about 4 knots. The wave eliminating effect rises the practical hullspeed to about double the speed normally achievable with a non-sleek displacer. +50% was measured in tow tank testings I got from the inventor while comparing it to a boat with the same length and weight. His calculation show a cruise speed at cadence of about 5.5 knots, but they are related from a 14 meter long boat. Because of higher efficiency in the drivetrain (in comparison bigger prop with slower speed), I am expecting a cruisespeed of nearly 7 knots.

@spidennis: The image is an external link to a picture on my unfinished project page, thats why I can´t resize it from here.

spidennis

02-14-2012, 09:12 AM

all that technology and can't resize a pic?
ok, here you go ......

Scheny

02-14-2012, 10:18 AM

Thx, I have changed the link now to a smaller thumbnail instead. I am not very used to writing in forums and have just now realized the attachment button for pictures ;)

I57

02-14-2012, 04:53 PM

Andreas
What sort of drive system are you going to use for the wave interference hull? If you were to use a drive leg would the extra drag affect the performance?

Ian

Scheny

02-15-2012, 02:09 AM

As the hull has some sort of a keel, it nearly pushes you for building an internal drivetrain, having the nice sideeffect of reducing drag. The "keel" has a "height" of 13cm on the stern, which suggests to use a 12x12 APC prop (30cm diameter) with a gearing ratio 1.333 times higher than for a 16x16. This gives the boat a nice draft of only 35cm and won´t affect the performance too much. Of course, it is possible to use bigger props too, but in this case, the driveshaft would be in water on a length of 0.5-1 meter, incrementing drag and the draft would also increment by 10cm (4'').

I plan to use a HTD belt with a 90° twist, as this method is absolutely maintanence and corrosion free and very cheap, as it will use only one custom built part, which can be lasercut very cheap. The whole drivetrain with the best and only new premium parts will cost me only 150€ (but can be built for half or less).

The highest amount of drag will result from the twin rudder arrangement, but anyone can build a single or dipping ones too. The major goal in research was convenience and not top speed. In my opinion, the advantage of stability, light weight and small storage area is worth to reduce top speed from 15km/h to 12km/h. The idea is to have the performance of a commercial 5m boat at half the dimensions and weight (and only a factor of the price). If there will once be series production, I want it to be as cheap as a series built race bicycle (not a carbon one ;))

As I said, it will not be the fastest HPB in the world, but I try to make it the best ;)

Greetings from cold Austria, Andreas

u4ea32

02-15-2012, 12:22 PM

Submarine Tom

02-15-2012, 02:14 PM

U4ea32,

Aren't you being kinda harsh on the guy for trying?

Let him run with it instead of wasting his energy arguing with you, dude.

Where about's in LA are you?

-Tom

Dennis A

02-15-2012, 04:01 PM

portacruise

02-15-2012, 09:31 PM

I think these are meant for low torque, high rpm power drill applications. Might work for awhile if rapid acceleration/prop weed entanglement etc. can be avoided.

Porta

I was browsing at the local Axminster tool centre and spotted a angle drive unit that could be used for a bent shaft over the side drive system This is a little lighter than i would like, but I think that it would be fully suitable for those with lower power out puts. It has ball race bearings, hardened pinion gears, 8 mm A/F hex input shaft and 10 mm keyless chuck. The handle holes are on both sides and could be used for fixing. The price quoted was £23.70 which is about 20% of the normally used industrial units.

Dennis A

Submarine Tom

02-15-2012, 09:34 PM

Squidly-Diddly

02-15-2012, 09:47 PM

B-70 Valkyrie mach 3 bomber.

No idea if concept could translate to surface vessel.

It was a shock cone it was surfing on.

Jeremy Harris

02-16-2012, 02:37 AM

I was browsing at the local Axminster tool centre and spotted a angle drive unit that could be used for a bent shaft over the side drive system This is a little lighter than i would like, but I think that it would be fully suitable for those with lower power out puts. It has ball race bearings, hardened pinion gears, 8 mm A/F hex input shaft and 10 mm keyless chuck. The handle holes are on both sides and could be used for fixing. The price quoted was £23.70 which is about 20% of the normally used industrial units.

Dennis A

Dennis, this is the same as the unit that broke on me at Beale Park last year, in the "Cordless Canoe Challenge". Having stripped it to do a post mortem I found that the bevel gears were held to the shaft by tiny steel pins that aren't able to take a lot of torque. They're OK for relatively high rpm, low torque, use, but I'd hesitate to recommend them for driving a large diameter prop.

Scheny

02-16-2012, 03:29 AM

Dude, it is impossible. Take a high school physics class. Put down the crack pipe.
I would rather encourage you, but at your level of intellectual development, that is impossible too.

Hallo David!

I know that promising -35% sounds somewhat unrealistic, but you have to count in the peripheral values. EVERY boat reduces wave buildup by lengthening the hull, as the angle with which the water is pushed aside gets smaller. This is how the hull length is calculated. I have to confess, that I am too sceptic about promised advantages bigger than -5% from someone new.

The approach of the displacement glider is something already tested and used since almost 20 years, it has only not been used in such a small boat. Increasing hull length is a somehow two-dimensional approach. The DG-hull cares about pressure distribution in three dimensions. The -35% only apply compared to a boat with the SAME DIMENSIONS AND WEIGHT. If you compare it to a boat like Will`s, with same weight, but twice the length, it will surely have worse characteristics than his.

As I said, it will not be fastest of any, but the fastest of its size. By the way, i have one master degree in safety relevant electronic engineering (and work in a company involved in your new space program too). For sure, this is not purely physics, but still I am not someone juggling with values too easily handed ;)

@squiddly-diddly: surfing on its own wave was spoken only literally. That was only a way to explain, how you can imagine the technology.

Hope I could strengthen your believe in this project a little bit. But to be true, I am also sceptical about the practical top speed, but I am convinced enough, that I have put in already many hundreds of hours.

Andreas

Jeremy Harris

02-16-2012, 03:48 AM

Andreas,

The key issue here is that the power needed to push a small boat through the water at low speed is almost entirely dominated by viscous drag (skin friction). Wave-making drag plays virtually no part in contributing to low speed drag at all, unless the boat waterline length is very short.

The key to minimising the power requirement (which is critical when you only have around 100 watts of power available for propulsion) is to minimise the wetted area for the length of hull needed to get the speed you're looking for. There are compromises, driven by things like ease of construction and stability, that mean that the ideal long, narrow, semicircular hull (which would give lowest wetted area as a rule) may not be ideal, but to go for a design such as you have suggested, where the wetted area is very high, seems a poor choice for such a low powered craft.

There is a good reason that pretty much all the successful pedal powered craft are converging on the same general hull form, long, narrow stabilised mono hulls or sometimes twin hulls. That reason is to do with efficiency, as many experiments have shown that hull form to need the least amount of power for a given speed.

portacruise

02-16-2012, 09:24 AM

Scheny:

Maybe the 35% reduction applies to high speed powered boats, something like a jet ski?

Anyway if it works at 100 watts, I want one!

Porta

Hallo David!

I know that promising -35% sounds somewhat unrealistic, but you have to count in the peripheral values. EVERY boat reduces wave buildup by lengthening the hull, as the angle with which the water is pushed aside gets smaller. This is how the hull length is calculated. I have to confess, that I am too sceptic about promised advantages bigger than -5% from someone new.

The approach of the displacement glider is something already tested and used since almost 20 years, it has only not been used in such a small boat. Increasing hull length is a somehow two-dimensional approach. The DG-hull cares about pressure distribution in three dimensions. The -35% only apply compared to a boat with the SAME DIMENSIONS AND WEIGHT. If you compare it to a boat like Will`s, with same weight, but twice the length, it will surely have worse characteristics than his.

As I said, it will not be fastest of any, but the fastest of its size. By the way, i have one master degree in safety relevant electronic engineering (and work in a company involved in your new space program too). For sure, this is not purely physics, but still I am not someone juggling with values too easily handed ;)

@squiddly-diddly: surfing on its own wave was spoken only literally. That was only a way to explain, how you can imagine the technology.

Hope I could strengthen your believe in this project a little bit. But to be true, I am also sceptical about the practical top speed, but I am convinced enough, that I have put in already many hundreds of hours.

Andreas

portacruise

02-16-2012, 09:32 AM

Hi, Jeremy:

Do you think using larger hardened pins would help, at least for your canoe challenge? Or is the plastic? housing likely to give way and let the hardened gears slip their mesh?

Porta

Dennis, this is the same as the unit that broke on me at Beale Park last year, in the "Cordless Canoe Challenge". Having stripped it to do a post mortem I found that the bevel gears were held to the shaft by tiny steel pins that aren't able to take a lot of torque. They're OK for relatively high rpm, low torque, use, but I'd hesitate to recommend them for driving a large diameter prop.

Submarine Tom

02-16-2012, 10:03 AM

There you go, thanks Jeremy, I knew somebody broke one. Could the pins be bored out larger and replaced with lower grad?

Jeremy, isn't Rick's world record breaking boat quite a contradiction to your last post (#1242)? Cat, square cross-section hulls, huge wetted surface area...?

Perhaps it's getting away from "low speed".

-Tom

Jeremy Harris

02-16-2012, 03:08 PM

The drill right angle 'box I broke had internal shafts that were about 3/16" to 1/4" diameter where the bevel gears fitted, with pins that were only around 1/16" in diameter. I reckon it'd be tough trying to get bigger pins into such a small shaft, although maybe they could be increased to maybe 3/32" or 1/8" maybe. Still not very big if it's driving a big prop at low rpm, IMHO.

Rick's using rectangular hulls because their easier to build, I believe, and the penalty for the sort of very narrow beam, pretty long, hulls he's making doesn't seem to be that significant I guess. The thing that bothers me about the design Andreas has posted is all that wetted area under the flat part of the hull. I believe that's going to add a lot of drag and result in a hull that will take a fair bit of power to move at anything other than very slow speed.

Submarine Tom

02-16-2012, 03:30 PM

I understand. Thanks for clarifying.

I was under the impression that Rick found the "square" hulls lower drag than round. I know he did extensive hull testing but perhaps he was willing to accept the marginal gains for ease of construction.

The square vs round has been a hot topic on other threads of late, just wanted to query.

Thanks again.

-Tom

I57

02-16-2012, 04:02 PM

Ricks V14 & V15 boats have square sections for ease of construction. He is able to make the boats very light as the design simplifies construction. His latest boat has an all up weght of about 20kg, this includes drive and outriggers. I am currently building a boat to Ricks V15 design, the reason is speed. I have designed and built my own boats but have only achieved 14kph in a sprint.
Greg K ( I can't spell his surname ) from Canada who did the world 24hr distance record used a boat designed by Rick. The hull had a rounded section and was about 8m long. This was a boat which was optimised for maximum speed and a lot of time and effort was put into it. Yes the rounded section is the best but comparing square vs round the differences for these type of boats is small.

Ian

Submarine Tom

02-16-2012, 04:03 PM

Thanks I57!

-Tom

Scheny

02-17-2012, 02:55 AM

I had a long conversation with Mr. Eder. He confirmed, that the boat will have an increased wetted area (I calculated 145% compared to the minimal possible at same dimensions), but he told me, that the -35% already include the increased wetted area.

The tank tests have been performed with a boat of 6m length, as far as I can remember, so his own 14m version may have performed a little bit better and my 2.6m version maybe will only have -30% consumption.

Anyway, you will get all technical data as soon as the prototype is built (and I will publish everything up to the last diagram, there will be no secrets :))

There are two other designs with a displacement-glider hull I would like to evaluate (with building/testing/planwriting there is no spare time left this year for me). If anyone is interested in building a kayak to be equipped with a Torqeedo Ultralight with following dimensions, he/she can contact me for plans:

Length: 3m
Width: 0.85m
Draft: 0.35m
Speed: 10kph (limited by prop)
Weight: 25kg (incl. motor)

Andreas