Pedal Powered Boat for the Baltic Sea / Coastline

[KalleA]

Hello,

having followed Rick W's threads on pedal/prop boats ("PPB") with great interest, I am beginning to seriously consider building a pedalboat myself. It would be an excercise and touring boat, to be mainly deployed along the Baltic coastline. I want the lightest and most efficient boat possible within the constraints of being able to safely handle the somtimes rough waters of the Baltic Sea. In essence, it should have the functionality of my sea kayak, but a more efficient and leg driven propulsion with electro/hybrid retrofit potential.

In all, the criteria and initial thoughts are:

1. Seaworhty enough for the Baltic coastline

2. Size. Around 8 m length (transport is a secondary concern, if any, but it should have decent maneuverability for the smaller rivers and waterways I would also pedal on)

3. Live Load. I weigh around 100 kg at 2 m height, plus say 10 kg for food/drink/eqpt.

4. Fit-out. Nothing beyond the seat/pedal/prop assembly. Perhaps I will need a bilge pump?

5. Hybrid. I would want to be able to retro-fit an electric motor at a later stage.

6. Driveline. Probably a normal crank/sprocket/chain/90 deg gears with a flexible propshaft. It should be possible to easily lift the prop out of the water for clearance/beaching. I am intrigued by pendular swing arms w roller cams as an alternative to the crank setup, but it's probably better keep it simple at this stage.

7. Superstructure. It should be an open boat, but I think with some form of fairing and/or wave deflection, given the conditions on the Baltic. Don't know how wet a performance optimised boat might get, but a cockpit with a spraycover secured to the cockpit rim, like on a kayak, might be an acceptable option. (Note: this is partly why the pendulum swing arms could be interesting, as they would allow for a lower superstructure than a crank/pedal setup.)

8. Construction. The boat should be as light as possible, and carbon over foam core would be OK w me, if it makes sense. Clearly, the best and cheapest weight reduction would come from lowering my CBD (Cheese Burgers/Day) intake...

9. Displacement. I'm guessing the boat w. outriggers incl. seat/driveline could weigh in below 30 kg + 110 kg live load = approx 140 kg.

10. Hull. This is one area (of many) where I am reasonably clueless, and would be grateful for input. From what I pick up here, I gather a long and narrow (wide enough to fit my bum inside) stabilised monohull should be the way to go.

What are the relevant considerations for the above conditions, and how might such a hull look?

Cheers

[Guest625101138]

A key input is the power you are able to develop or would reasonably achieve with some training on the boat.

If you do not have an idea of your power level then head off to a gym and find a recumbent cycling machine that has adjustable load and a power meter. Most reasonable ones have this but you need to know how to adjust it to get the data. If there are three machines then try all three to see that they give similar results ie the power indicated matches the effort. Find the load setting that feels easy and spin a bit faster than loafing along. This is usually around 70rpm.

You need to cycle for about 1 hour and see what is comfortable after this time.

If you have a road bike then you can get some idea from the speed you can sustain on flat ground.

There are other methods that are quite accurate and involve finding a building with about 10 stories or more and doing a few trips up and down the stairs.

The engine is a vital part of the design.

If you already have a good idea on your power output then just advise accordingly.

Rick W

[KalleA]

A key input is the power you are able to develop or would reasonably achieve with some training on the boat.

If you do not have an idea of your power level then head off to a gym and find a recumbent cycling machine that has adjustable load and a power meter. Most reasonable ones have this but you need to know how to adjust it to get the data. If there are three machines then try all three to see that they give similar results ie the power indicated matches the effort. Find the load setting that feels easy and spin a bit faster than loafing along. This is usually around 70rpm.

You need to cycle for about 1 hour and see what is comfortable after this time.

If you have a road bike then you can get some idea from the speed you can sustain on flat ground.

There are other methods that are quite accurate and involve finding a building with about 10 stories or more and doing a few trips up and down the stairs.

The engine is a vital part of the design.

If you already have a good idea on your power output then just advise accordingly.

Rick W

Many, many years and kgs ago, I used to be a cyclist. My VO2 max was around 80 ml/kg/minute. Present engine capacity is hardly worth testing, but I guess that, with a bit of training, somewhere in the 120 to 150 W range might be realistic for longer period sustained level.

I've got my eyes on a nice recumbent trike for getting back into something resembling shape.
http://www.hpvelotechnik.com/produkte/scorpionfs/index_d.html

http://img262.imageshack.us/img262/1813/scorpionfslinksgraubl.jpg

Cheers

[Tad]

See http://www.gartsideboats.com/blueskies.php for a successful boat of this type.

She's 20' by 3'4", weight about 250 pounds.

[KalleA]

See http://www.gartsideboats.com/blueskies.php for a successful boat of this type.

She's 20' by 3'4", weight about 250 pounds.

Yup, Blueskies is pretty. Hadn't seen her before:

http://img216.imageshack.us/img216/9810/blueskies1.jpg

Too heavy, wide and comfort oriented for what I am looking for though. 250 pounds is heavy. My rowing boat only weighs around 30 kg:

http://img235.imageshack.us/img235/2608/explorer46sidanrauiri.jpg

Noticed that Blueskies is a stitch-and-glue build. I've recently seen some very nice stitch-and-glue kayaks (glass/epoxy over spruce) that compared very well with carbon fibre kayaks of similar design and dimensions - the weight was very similar to my total surprise.

Cheers

[Tad]

stitch-and-glue build.

I usually associate stitch and glue with plywood hull skins. Paul states that BlueSkies was built "canoe fashion, of strips over temporary molds, then glassed inside and out."

[KalleA]

I usually associate stitch and glue with plywood hull skins.

My bad. I think everyone associates stitch-and-glue with plywood hull skins.

Paul states that BlueSkies was built "canoe fashion, of strips over temporary molds, then glassed inside and out."

That's what my dyslectic mind wanted to say: strip building!

http://img165.imageshack.us/img165/6613/news0501065.jpg

Cheers

[Guest625101138]

A 140kg displacement hull optimised for 6kts (3.1m/s) requires 114W on the hull or about 140W at the pedals. It has 7.7m LWL and 0.3m BWL.

This would be a likely starting point. For ease of build you would go to single hard chine. This will make it narrower on the WL and shorter as well. Power will go up a fraction.

I doubt that there would be value in making a hull wide enough to sit in. There is really no advantage if it has outriggers. If you intended to have a boat that could handle any conditions then you would go for a ballasted keel to give stability. There is merit then in going wider to lift the metacentric height and also sitting lower to reduce the CofG.

Fairing around the seating position would make it more comfortable in a seaway. This could be made as a bolt-on module and include all the drive components as well as the outrigger mounts. The seat could be part of the fairing.

Rick W

[KalleA]

I doubt that there would be value in making a hull wide enough to sit in. There is really no advantage if it has outriggers. If you intended to have a boat that could handle any conditions then you would go for a ballasted keel to give stability. There is merit then in going wider to lift the metacentric height and also sitting lower to reduce the CofG.

Fairing around the seating position would make it more comfortable in a seaway. This could be made as a bolt-on module and include all the drive components as well as the outrigger mounts. The seat could be part of the fairing.

Rick W

1. Thanks for all the input.

2. The idea of a bolt-on module as you outlined is very appealing.

3. My initial thinking re the hull was that, given the Baltic waves, the lower COG from a lower seating position inside the hull would add some initial stability, with the outrigers for ultimate stability. A bit like a longer, possibly narrower, propeller driven sea kayak. (In a kayak, apart from hull shape, one uses body balance, paddle and ultimately eskimo rolling, neither of which is possible with a propeller boat.)

I.e. something between this:

http://img368.imageshack.us/img368/9214/gkp5280007743190.jpg

and this:

http://img368.imageshack.us/img368/2610/within.jpg

(Both pics from http://www.adventuresofgreg.com - an incredible source of information!)

4. I understand that there will be a point, depending on the expected wave/weather conditions, where a keel becomes the preferred option to outriggers. At what sort of wave heights might that be?

I have studied the wave data for the Baltic, and was surprised at the annual variances in mean significant wave height - from less than 0,5 m to over 1,2 m from one year to another, wave frequency is 3 - 4 s. Would one be right in assuming that such conditions, even 0,5 m wave heights, already favour the keel approach?

Cheers

[Guest625101138]

Here is a first go of something that is quite easy to build in flat panel. The cockpit tops would need to be single side flat panel and then outside done after placing.

This boat has a hull power of 120W at displacement of 145kg.

I can operate in waves to about .6m but it gets uncomfortable because I get green water over the seat. OK if it is hot.

Fairing would make waves more tolerable. The stability is a matter of having enough buoyancy in the outriggers up to about 1m waves. If you want to operate in an angry sea with bigger than 1m waves then you should really go for the deep keel.

I have been out in 70kph wind but only with short fetch distance so waves only around 0.6m. Under these conditions my greatest concern is just getting blown over with wind picking me up as I crest a beam sea. Of course if they are gentle waves left over from some weather then they do not present too much problem.

The higher you sit the more influence your body has on dynamic stability. Once you get a bit of speed up it is surprising how much roll you can induce by steering adjustment. George Tatum's Wavebike made use of this and was dynamically stabilised once under way. It had tiny outriggers that were spring deployed just before coming to rest. (see dragrace image)

If you are likely to encounter 30+kph winds in open water some distance from shelter then a keel is probably a better option. It will not perform as well as the sit-on hull.

Rick W

[KalleA]

Here is a first go of something that is quite easy to build in flat panel. The cockpit tops would need to be single side flat panel and then outside done after placing.

This boat has a hull power of 120W at displacement of 145kg.

Looks very nice, and quite buildable. What software do you use? Seems I will have to try and learn to use something like that.

I can operate in waves to about .6mm ...

Wow! You are very precise...:D :D

Fairing would make waves more tolerable. The stability is a matter of having enough buoyancy in the outriggers up to about 1m waves. If you want to operate in an angry sea with bigger than 1m waves then you should really go for the deep keel.

I think that what you have produced here will be a good starting point for my first pedal boat. Better get something on the water and gain some experience for potential future iterations.

There seems to be a lot of practical building information on http://www.adventuresofgreg.com, so I'll give that a thorough read now.

Thanks for all the help!

Cheers

[Guest625101138]

L

Wow! You are very precise...:D :D



..

One too many "m" s. I think of wave height in feet- so 2ft. Going to windward that is the height of wave that will keep coming over the deck with enough height to drench the seat. I usually slow down to allow the boat to pitch enough.

I use Michlet/Godzilla to determine the optimum hull form and then load the resulting hull offsets into Delftship Pro for the rest of it. You can get a free version of Delftship that has most of the functions of the Pro version. The basic Pro version is low cost and I felt compelled to make my donation to the developers because I have had a lot of value from it.

Greg is doing a good job of blogging his activities. He generally does good work. He has time to test ideas put to him. He made a mess of the the propeller he fabricated but he solved that by getting the next one milled and it was very nice. Actually it took the machine shop 4 goes and two were OK. Only one was near perfect. Actually it turned out better than my original design because it ended up thinner than design after polishing it. I actually compared it with my V11J prop on his boat.

Rick W

[Guest625101138]

Regarding the wavebike - George used to ride it in the surf. He could get a good portion of the hull air borne when driving through waves. It had a monstrous rudder so small movements generated large steering force.

Rick W

[KalleA]

I use Michlet/Godzilla to determine the optimum hull form and then load the resulting hull offsets into Delftship Pro for the rest of it. You can get a free version of Delftship that has most of the functions of the Pro version.

I've downloaded and installed Delftship now. Can't find any download links for Michlet/Godzilla though. Any tips as to where to find that?

Cheers

[Guest625101138]

It is no longer being supported so was removed from the cyberiad site.

Rick W

[KalleA]

It is no longer being supported so was removed from the cyberiad site.

Shame. From what I've read, it sounds like a useful and interesting application.

1. Do you know if the information on the cyberiad site about an upcoming new version 9.01 still is current and correct?

2. Would it be illegal / improper / impossible to get hold of a copy? I understand it is/was freeware?

Cheers

[KalleA]

Here is a first go of something that is quite easy to build in flat panel. The cockpit tops would need to be single side flat panel and then outside done after placing.

This boat has a hull power of 120W at displacement of 145kg.

Having looked at the design, I have a few questions (that probably show that my vehicle building eperience to-date is confined to racing cars):

1. Is there an "optimal" longitudinal positioning of the outriggers? I've noticed that on your boats, they are normally behind the pilot.

2. Should the arms that transversely fix the outriggers (akas?) be perfectly stiff, or might there be some advantages from a "suspension"?

3. From the plans, I get the impression that it could be possible to lower the seat slightly into the deck, like on a surfski. Would such a lowering of the COG be beneficial in any way?

Cheers

[Guest625101138]

Having looked at the design, I have a few questions (that probably show that my vehicle building eperience to-date is confined to racing cars):

1. Is there an "optimal" longitudinal positioning of the outriggers? I've noticed that on your boats, they are normally behind the pilot.
The main reason I do this is so I do not have to hop over an outrigger to get into the boat. If you mount them a long way back you can get them to ride the divergent wave at a normal speed but the end up well aft. The reason I put them beside the cockpit was to get the iakos high. They need to be clear of green water otherwise the slow you down when they hit waves. This is a far more important drag component to consider for rough water operation.
2. Should the arms that transversely fix the outriggers (akas?) be perfectly stiff, or might there be some advantages from a "suspension"?
My iakos are a torsion arm. They will ride over little waves with less drag than if they were rigid but my outriggers are shorter than what you need.

3. From the plans, I get the impression that it could be possible to lower the seat slightly into the deck, like on a surfski. Would such a lowering of the COG be beneficial in any way?
You can lower the seat and still have the cockpit self-draining but it creates a weak point in the structure and makes it harder to build. The deck as I have drawn it is a flat plane. Very simple to build.

Cheers

What I provided is intended to be easy to build and perform well. There are a myriad of variations. I was not too careful with the detail of the cockpit set up as I just put it around one of my frames. I expect it is slightly too narrow. It needs to be as wide as the deck. The clearance for pedals also need to be checked.

I have attached a couple of photos showing different outriggers. I really like the conical ones but they are harder to make than the ones depicted on KA77.

The only time I have completely capsized pedal boats is when I have been using a single outrigger. This is one of the reasons I like two.

These boats respond reasonably well to "body english" so in some ways there is an advantage in sitting high. The standard seating position in an OC1 is about 100mm above water level and this is roughly what I achieve. The advantage in sitting low is less windage but then with fairing this would not be so much of an issue. THe KMT is so low that getting a few centimeters lower will not make much difference. You rely on outriggers for static stability and body english in conjunction with the rudder once moving.

The dipping rudders I have on V11J do not respond well enough for dynamic stability so I rely solely on shifting weight. This is somewhat annoying but I put up with it so I have less drag. On KA77 I have shown a decent size under hull rudder. This will be very powerful and will cost about 5W but essential for a seaway.

Rick W

[KalleA]

I have attached a couple of photos showing different outriggers. I really like the conical ones but they are harder to make than the ones depicted on KA77.

Wonderful looking creations! Guess the yellow "banana boat" is based on a kayak? Finish looks really professional.

What's the best approach to making the conical outriggers? Laminate and vacuum bag four cones over a male mold, and then bond them together butt-to-butt with a re-inforcing strip? Does one fill them with foam?

The orange boat looks very intriguing, and promts a few thoughts. As my planned operating conditions seem to possibly place me in the borderline zone between outriggers and keel, I wonder if a keel approach could be combined with submerged bouyancy?

1. Assume a keel of, say, 30 kgs and 1 m below the waterline. This could result in an empty weight of around 50 kgs, I guess, and a total displacement near 160 kgs.

2. If the submerged hull were to be 1 m below the waterline, I'm guessing that a cylindrical/torpedo shape might be good (minimizing wetted area)?

3. The idea would be to place the keel weight on the "inside bottom" of the submerged hull. I.e. a combined submerged hull/keel. Does that make any sense, or would it just be the same as making a less bouyant submerged hull (can't get my mind fully around that)?

4. No idea what's the right superstructure approach with submerged bouyancy - does one just have a "pod" on/above the waterline, or does one go for, say, an iLAN hull with very low displacement?

5. For flexible draft, and some practical means of entering and exiting the boat without stabilisers, perhaps the submerged hull could be mounted on a daggerboard-like arm, so that it could be raised to touch the underside of the superstructure/upper hull. Since the top of the upper hull (deck?) would be above the waterline, sealing the leg ought not to be necessary/critical.

6. As an underwater leg would be in place, could it make sense to mount the prop at the end of the submerged hull, with the angular gearbox inside the hull (disregarding the issues of access) and driven by a chain/sprocket from the crank?

7. Might the added drag from the "daggerboard/drive leg" and possibly greater displacement be compensated for by less wave drag (or whaterver the correct term is)?

8. How did that orange creature perform?

Cheers

[Guest625101138]

Submerged buoyancy does not work unless the majority of the mass is contained within the submerged buoyancy. I have tried it with two examples, V5 and V8. The first one almost drowned me. The second one took 2 hours to work out how to get on it.

The wave drag on KA77 at 6kts is 3% of the total drag. There is nothing you can do with other designs that will get less than this. You can get zero wave drag but the hull has more wetted surface so viscous drag goes up.

V7 is a Pahoa OC1 built in Australia. It is built from moulds. The canoe cost AUD3500 and the main hull weighs 16kg. It had a slight modification to allow for the drive frame. The frame weighs 10kg and was built be Greenspeed recumbents. It cost AUD1050. It was my pride and joy but did not work much better than V6. Total boat weight is 28kg. I can build lighter now. V11 design is about 1kph faster for the same power. That is a huge difference when you know that power is a cube function of speed.

V10, the orange boat, was a dog. It sat flat but under way it had a tendency to nose dive. I could not easily alter the seating position to lift the bow. I think I got it to 13.5kph.

I re-analysed all the hulls I have used once I got Michlet and it confirmed what I had already learnt about the drag.

The best option for a keel is to increase the inherent stability of the hull and place a small lead weight as deep as you can realistically go. Also sit within the hull. You could expect to achieve around 5kts with this set up. It is no longer beachable unless the keel can be retracted. This makes it twitchy to board. It ends up being a heavier boat. It really needs a trailer for transport.

Rick W

[KalleA]

Submerged buoyancy does not work unless the majority of the mass is contained within the submerged buoyancy. I have tried it with two examples, V5 and V8. The first one almost drowned me. The second one took 2 hours to work out how to get on it.

It seems there's almost nothing you haven't considered, and in many cases actually tried and tested. Your generosity and patience in sharing this wealth of knowledge is greatly appreciated.

I gather you have now pretty much nailed it as far as high performance pedal powered boats are concerned - i.e. that further potential improvements are likely to be small, and found in fine-tuning efficiencies, rather than in conceptual quantum leaps. How will your current project differ from it's predecessor(s), is it mainly in lower weight?

I understand that KA77 represents pretty much the performance optimum for its intended live load and deployment conditions, and that the main potential for further efficiency/performance gain could be in using a smaller rudder for calmer waters and yours truly losing weight. A couple of final questions:

1. What sort of performance would be gained from, say, a 15 kg reduction in live load? How far from "optimum" would the hull be in such a case, as designed for a slightly higher displacement?

2. How does a stronger engine influence optimal hull shape? If memory serves me well, I figure it should be possible for a good cyclist to push out over 300 W for a couple of hours. Not that I have any intention or ability to get back to such levels, but just out of curiosity.

3. You mentioned that you prefer conical outriggers. What is the reason?

4. I'm trying to get my mind around Delftship now, in order to be able to play around with a superstructure to fit my dimensions. Would it be possible to get a copy of the .fbm file?

Cheers

[KalleA]

V7 is a Pahoa OC1 built in Australia. It is built from moulds. The canoe cost AUD3500 and the main hull weighs 16kg. It had a slight modification to allow for the drive frame. The frame weighs 10kg and was built be Greenspeed recumbents. It cost AUD1050. It was my pride and joy but did not work much better than V6. Total boat weight is 28kg. I can build lighter now. V11 design is about 1kph faster for the same power. That is a huge difference when you know that power is a cube function of speed.

Out of curiosity, I looked up the Pahoa:

http://img530.imageshack.us/img530/8891/pahoalg.jpg

The Pahoa is 630 cm, so substantially shorter and, I guess, quite a bit heavier than the V11. So, the combination of hull dimensions/shape and displamement meant a 10-ish per cent speed improvement, which would otherwise have required a 30 per cent more powerful engine, is that about right?

If one wanted to use an existing hull, and convert it to pedal/prop, I would have thought that putting outriggers on a single sculler rowing boat might be the most efficient route. At approx. 8 m loa, 30 cm beam and 14 kg (regulated min weight), how far is such a boat from your optimised hulls?

Cheers

[Guest625101138]

Reducing weight by 15kg would reduce power requirement by maybe 5W. It is that order.

If you were designing for a tronger engine the design speed would be higher. The resulting boat is likely to be shorter to reduce wetted surface.

The conical outriggers wave pierce very nicely. I like this because the outriggers do not upset the attitude of the boat. They may not be the best for rougher conditions. The ones you see on outriggers have elevated bows but then modern OCs only have one outrigger and you cannot afford having it buried.

The fbm file is attached. Don't worry too much about the drive frame. This was just taken from an existing model. It will give you the proprtions.


The Pahoa is a nice hull in rough water but mine is not self-draining so it sort of defeats the purpose. I did not want a rough water boat. I could not justify the AUD7000 for a new single scull to the treasurer but it was my preferred hull. The reason I went for the Pahoa was the cooperation of the supplier/builder to make some small changes.

The scull is not quite as good as an optimised hull for pedal power. An optimised pedal boat with an elite cyclist would outperform an olympic sculler. Sculling does not have the biomechanical efficiency of cycling and the hull speed fluctuates quite a lot during the stroke. The hulls tend to be longer than the ideal pedal boat for the same weight. A lightweight mens would be very close to ideal for you. If you can get one second hand it is a good starting point. You may want to put more buoyancy in the bow. The red and boat in this clip is a women's single scull that was provided free to Pete:
http://www.youtube.com/watch?v=ckWqIgmVM4Y

Rick W

[KalleA]

An optimised pedal boat with an elite cyclist would outperform an olympic sculler. Sculling does not have the biomechanical efficiency of cycling and the hull speed fluctuates quite a lot during the stroke.

A friend of mine, who is a former olympic sculler, pointed out that the body movement constricts lung volume/oxygen uptake, and that you must adjust your breathing to the stroke frequency rather than breathe however might be individually optimal. It seems the pedaller has a number of advantages over the sculler. It would be really interesting to see a direct comparison/race where the only variable was the propulsion system and the engine.

Cheers

[Guest625101138]

A friend of mine, who is a former olympic sculler, pointed out that the body movement constricts lung volume/oxygen uptake, and that you must adjust your breathing to the stroke frequency rather than breathe however might be individually optimal. It seems the pedaller has a number of advantages over the sculler. It would be really interesting to see a direct comparison/race where the only variable was the propulsion system and the engine.

Cheers

A true comparison would involve both boats and propulsion systems optimised. The hull for the pedallerwould be somewhat shorter because the thrust is steady and speed is constant. The scull should have a sliding rigger as this is better than just a sliding seat.

Going on what olympic scullers can achieve I expect a sprint cyclist would win quite easily in a pedal boat. Also at these higher power levels foils are feasible with a pedal boat and you would expect that a pedal boat with fairing could outperform a rowing 8 over 2000m. The speed variation for a sculler would not be very good for foils.

The fastest single person pedal boat has achieved almost 19kts - close to twice the speed of a single sculler.

Rick W

[KalleA]

A true comparison would involve both boats and propulsion systems optimised. The hull for the pedallerwould be somewhat shorter because the thrust is steady and speed is constant. The scull should have a sliding rigger as this is better than just a sliding seat.

Going on what olympic scullers can achieve I expect a sprint cyclist would win quite easily in a pedal boat. Also at these higher power levels foils are feasible with a pedal boat and you would expect that a pedal boat with fairing could outperform a rowing 8 over 2000m. The speed variation for a sculler would not be very good for foils.

I agree that a true comparison should have each hull optimised for the respective propulsion, and that putting the pedal/prop on a scull hull would impose a relative disadvantage. Still, I guess it would win comfortably, particularly over longer distances. I think that this would perhaps be the most powerful display of the advantages of pedal/prop. Simple for anybody to understand: "put a pedal/prop on a boat and it goes faster..."

The sliding rigger is obviously superior to the sliding seat, but nobody seems to even realise that they exist. Ever since they were banned from competition in the early 80's, they seem to have disappeared. You don't even see them on the lots of non-regulated boats, where the sliding rigger makes tons of sense.

My underlying thinking was that pedal/prop (done properly) is a much better option for many forms of leisure/pleasure and performance boats than people in general realise, and that some simple comparisons/races might be the most powerful and effective way to convey that.


Hydrofoils are cool, and probably the most efficient aproach for a sprint, but they are hardly practical for anything beyond just that - a shortish sprint with a powerful engine - are they? By the way, I just saw some very impressive hydrofoil kayaking on YouTube: "Hydrofoil Kayak Vs K1 Sprint Kayak" http://www.youtube.com/watch?v=U95UReP4mdo

http://img142.imageshack.us/img142/593/flyak1.jpg

Cheers

[Guest625101138]

I understand the Flyaks top out at around 25kph. Decavitator did 37kph. When you think speed is a function of roughly speed squared for foils you start to realise how superior pedal is.

With optimising foils you could target about 20kph for long distance operation of one to two hours with a top athlete.

Greg K has more or less demonstrated the advantage of pedal power over long distance.

I think it will be a long time before pedal power has any serious recognition. Most people conform to the norm. It also has taken a lot of effort to overcome some of the basic weaknesses compared to paddling. I still take a paddle as a back-up when I go long distances. Kayakers do not vcarry a spare paddle. So reliability remains an issue.

Rick W

[KalleA]

I understand the Flyaks top out at around 25kph. Decavitator did 37kph. When you think speed is a function of roughly speed squared for foils you start to realise how superior pedal is.

With optimising foils you could target about 20kph for long distance operation of one to two hours with a top athlete.

So, with a small electric motor and some modest battery capacity (say 1 kWh of Lithium batteries), one could have a really fast little boat with some decent range, and capable of some pretty impressive sprints.

Greg K has more or less demonstrated the advantage of pedal power over long distance.

He has indeed, though 24 h is an insane period. How fast would an optimised non-hydrofoil boat go with 400 W at the pedals? This is what I believe a world class cyclist can sustain for a few hours.

I still take a paddle as a back-up when I go long distances. Kayakers do not vcarry a spare paddle. So reliability remains an issue.

An issue the size, weight and cost of a paddle...

Cheers

[KalleA]

OT

I just found this battery from Torqeedo, http://www.torqeedo.com/en/hn/products/power/technical-data-measures.html.

http://img90.imageshack.us/img90/3779/torqueedopower2677.jpg

At 2 kWh and 19 kg, it's probably a bit too big for adding to a pedalboat. At least it's reasonably long and narrow for going deep into the hull. At 3.300 Euro, it isn't exactly cheap.

Cheers

[Guest625101138]

There is discussion on electric foiler on this thread:
http://www.boatdesign.net/forums/boat-design/electric-foiler-foil-assist-25980-3.html
http://www.boatdesign.net/forums/attachments/boat-design/29230d1234253339-electric-foiler-foil-assist-6m_foiler.png

The best lift to drag you can get on a small foiling boat is around 20. So a boat that weighs 100kg will have a water drag of 50N. Windage will be significant as well - say 10N. So total drag is 60N.

I understand Lance Armstrong can sustain 460W over 20 minutes. So in a good foiler he would be nudging 8m/s as a sustainable speed and something higher in a shorter sprint over 2000m.

Rick W

[KalleA]

There is discussion on electric foiler on this thread:
http://www.boatdesign.net/forums/boat-design/electric-foiler-foil-assist-25980-3.html
http://www.boatdesign.net/forums/attachments/boat-design/29230d1234253339-electric-foiler-foil-assist-6m_foiler.png

The best lift to drag you can get on a small foiling boat is around 20. So a boat that weighs 100kg will have a water drag of 50N. Windage will be significant as well - say 10N. So total drag is 60N.

Thanx for the link.

I understand Lance Armstrong can sustain 460W over 20 minutes. So in a good foiler he would be nudging 8m/s as a sustainable speed and something higher in a shorter sprint over 2000m.

So, on the typical rowing distance of 2.000 m, Lance would take around 4 minutes. To be compared with Drysdale's single scull world record of 6 min 35 sec, or the M8+ world record of 5 min 20 sec...

Now, how fast would Lance be in a "traditional" displacement boat, i.e. with no foils?

Cheers

[Guest625101138]

The 460W would get 6m24s. I expect that over 6 minutes an elite cyclist training for 5 minute output would do significantly better than this power though.

Rick W

[KalleA]

The 460W would get 6m24s. I expect that over 6 minutes an elite cyclist training for 5 minute output would do significantly better than this power though.

Right. In other words, a cyclist would comfortably beat a sculler - even on a hull optimised for sculling, in conditions optimised for sculling (flat water) and on a distance optimal for sculling. On longer distances, and in rougher seas, the cyclist would totally outclass the sculler. Give the cyclist an optimised boat, and the difference becomes even greater.

I bet you very, very few people know that.

Cheers

P.S. With "cyclist" vs. "sculler", I obviously mean pedal/prop vs. the archaic concept of sliding back and forth whilst lifting, turning, lowering and dragging a couple of sticks through the water...

[Guest625101138]

I doubt that there are very few people who know a single person pedal boat has hit almost 19kts over 100m. When you think that power in flight mode is roughly square of speed you can appreciate how significant this is over the speed achieved with rowing sculls.

I have never asked the question but I am betting that when the designers of Decavitator were contemplating 20kts in a human powered boat they did not contamplate oars as the likely means of propulsion. If they did I expect it would have had fleeting consideration.


Rick W

[KalleA]

Hydrofoils sound really interesting for lightweight electroboats. What are the drawbacks? What about seakeeping? How does a foiler perform in various weather conditions, compared to a stabilised monohull?

Cheers

[Guest625101138]

The only boat I flew was V8 with its submerged buoyancy. I have added a foil to V7 but only got partial flight before uncontrollable roll.

It was like a cushion of air in waves up to about 1ft or so. Would be the same with a foil. Once waves hit the hull it will slow you down.

A foiler brings in even more complexity than just the propeller. It would be OK on a rowing course. In operation on open water there is the problem of the foils fouling. For a boat weight of 120kg you would need to sustain 250W to make it worthwhile over displacement mode. There is extra drag if you want to operate at reduced effort without flying.

I looked at it very closely for Greg's record attempt but displacement mode was best at his sustainable power level.

Rick W

[KalleA]

I think I will try to summarise what I believe I've learnt sofar:

1. For wave conditions up to around 0,5 metres, the long-and-narrow stabilised monohull is the most efficient hull approach. Such a boat, optimised for 145 kg displacement and with a 140 - 150 W engine will cruise along at 6 knots.

2. If one can push out 250 - 300 W continously, the hydrofoil becomes viable, and speeds around 20 knots obtainable. This may be out of reach for the vast majority of pedallers, but easily achieved with a tiny electric motor.

3. As waves get closer to 1 m and above, a keel will be required for seaworthiness. The added weight and drag from the keel will shave about one knot off the speed with 150 W at the pedals, i.e. 5 knots instead of 6.


For me, the preliminary conclusion is to begin with a stabilised monohull, the KA77, but with an eye to eventually re-configure it with an added electric motor and retractable foils along the lines of what you outlined in the "Electric foiler" thread. The idea of being able to speed along to one's destination, and then pedal around in, say, the nearest archipelago, is very appealing.

Cheers

[Guest625101138]

This is a good summary in relation to a single person craft.

The sea keeping ability of a boat is a function of size. An outrigger stabilised monohull for a larger crew size would be suitable for heavier conditions. With a very large crew with a boat weight getting near 2t you could get a stabilised monohull with ocean going ability.

Rick W

[KalleA]

The sea keeping ability of a boat is a function of size. An outrigger stabilised monohull for a larger crew size would be suitable for heavier conditions. With a very large crew with a boat weight getting near 2t you could get a stabilised monohull with ocean going ability.

Right, it's of course shown by iLAN boats such as EarthRacer, that stabilised monohulls can be oceangoing.

So, what's the low-down on outriggers vs. keel, shape vs. gravity?

- Performance and efficiency. Could one say that, for a given live load, a keel approach will, typically, always be heavier and have more drag than an outrigger solution?

- Safety. Is one aspect safety and self-righting ability? I.e. that a keel might ultimately be safer, as one can avoid staying upside-down.

- Comfort. I sort of visualise/imagine that, in rough and choppy seas, the waves could lift the outriggers and rock the boat in ways that might be more uncomfortable than a keel in similar conditions. Is that so?

Sorry for all the novice questions on basic stuff. I am getting some litterature this weekend to accellerate the learning curve. Any books to recommend?

Cheers

[Guest625101138]

You can achieve self-righting without a keel providing the pilot is belted in. My V12 achieved this although it did not ever get to the lid stage to completely seal it up:
http://www.youtube.com/watch?v=PYoW3XjHRbw
It had no keel. It had swing arm drives so my legs did not need to go very high. My CoG was 380mm above the keel and the KMT was 420mm. So stable once seated but absolutely impossible to board unless someone held it upright until I was seated.

Greg's first ocean boat also achieved self-righting with only internal ballast. The deck he built was quite high and heavy so it ran the risk of sitting on its side without the ballast. The slide out outriggers allowed him to stand up in it once they were deployed.

From a pure speed perspective fo a ballasted boat there is some optimum where a deep keel combined with a hull that you sit into is better than an internally ballasted hull. But there are a whole lot of issues with a keel. The overall fastest is the outrigger stabilised monohull but then it is not self-righting.

The comfort aspect is difficult for me to say. Sea motion does not bother me too much. If I feel secure I am comfortable. I start to feel insecure when bouncing across waves tops at 40kts. That will not happen in a pedal boat. I like the way a deep keel yacht lifts to quartering waves without hardly altering heel. I would not take any of my current pedal boats into open ocean as they do not have the strength to cope with heavy seas and are borderline stable. It would be like taking a racing kayak or rowing scull out there.

The second sea trial Greg did used a deep keel with enough weight to allow him to stand. I think he preferred this motion but it still made him seasick.

There are comfort factors but I believe they are somewhat subjective. Plenty of people get seasick on ocean liners at the point they start to feel the swell.

Rick W

[KalleA]

You can achieve self-righting without a keel providing the pilot is belted in. My V12 achieved this although it did not ever get to the lid stage to completely seal it up:
http://www.youtube.com/watch?v=PYoW3XjHRbw
It had no keel. It had swing arm drives so my legs did not need to go very high.
From a different thread http://www.boatdesign.net/forums/boat-design/paddle-vs-pedal-26668.html#post265316:
The critical part of the design is to link the two arms via the pull cord so you get an enforced motion or simple harmonic motion. I did a dynamic model of the legs and swing arms to optimise the geometry. It is a very pleasant motion for a relaxed pace and I am reasonably confident can be set up to be more efficient than cycling.

Do you have any details on your swing arm drive? Like what you used for stroke length, arm length, axle diameter, pull chord geometry, return springs (if any), etc. At first, I felt it would involve too much fabrication work compared to just using a bike crank with pedals, but maybe it's doable. I figure one fabricates a couple of axles that bolt onto the crank, just like the pedals. Then the roller bearings are fixed inside the swing arms and slid onto the axles. A bit or lathe and mill work, but nothing complicated.

Swing arms interest me for a number of reasons - the lower COG, the lower fairing, the motion as such, and the potential to use the same frame/setup for a FrontRower setup for shallow waters.

From a pure speed perspective fo a ballasted boat there is some optimum where a deep keel combined with a hull that you sit into is better than an internally ballasted hull. But there are a whole lot of issues with a keel. The overall fastest is the outrigger stabilised monohull but then it is not self-righting.

I believe your Faux-Tri concept is self-righting, right?

Cheers

[Guest625101138]

Look at posts #73 and #75 on this thread:
http://www.boatdesign.net/forums/boat-design/pedal-powered-boats-23345-5.html

The wire had mechanical advantage over me. I stroked my feet about 400mm and the chord stroked 600mm. This is not fixed. If desired you can reduce or increase stroke.

The length shown in Warren's boat were taken from what I determined to be optimum. With a tall person it might be different. At a cadence of 60 and at low power level it is more biomechanically efficient than cycling.

The swing arm system has a major drawback in that there is no reverse. Until you do not have it it is hard to appreciate the value of reversing (or stopping) on demand.

The no load tension in the system impacts on efficiency and has a lower limit for the intended speed of stroking. You cannot pull back on the pedals so cleats cannot be used.

The saving you would make in lower CofG is not worth the trouble for an outrigger stabilised boat.

The faux-tri is intended to be self-righting. It will rely on having batteries locked down in the central hull to achieve this. The lighter the solar the cells the better as well.

Rick W

[spidennis]

after googling most of the day, and reading and watching tons, I came across this thread and the links included and have been here quite awhile now!

I too have plans on using pedal power in a "one off" boat. I want to build something like a sea kayak / surfski cross using the hobiecat mirage drive in a "foamie" design. I haven't found much in the way of photo documentation on building a foamie boats except for here:
http://www.ptone.com/Kayak/surfboat/building/
I wish I could find more about this style of building as this i believe is gonna be the best method for me (easy). I watched a bunch of youtube videos about shaping surfboards but a kayak is quite a bit more involved. I was wondering on is there any kind of patterns to be made or used to help shape the hull and deck? I hadn't yet built a boat but for some reason I awoke this morning thinking that this is the time and way about doing this.

there's the 260 mile Texas water safari race about to start in a few weeks and I'd like to enter it next year. It's mostly a shallow river race with an open bay section at the end. I believe that using both paddle and peddle of the mirage drive, I can exhaust my whole body by the time I got to the finish line.

there's also the adirondack 90 miler that I'm gonna enter this year but I'll have to paddle it this year, next year will be different!

so after I look around at various boats on line and come up with a hull and deck design, and i think i can build it, then comes the tough part, building it! any suggestions would be welcome!

edit:
one more thing ....
since I live at the beach, and we have great sand for sandsculptures, and I'm a sandcastle instructor, I figure I'd practice my hull designs 1:1 in sand on the beach. If I did this in my backyard I'd suppose I could use the sand sculptured hull to build a mold and fabricate a boat with that method instead? would that be possible?

[Guest625101138]

The Mirage drive is not very efficient. At best you could expect 50% efficiency. A good prop will get 85% efficiency.

Using both arms and legs is only advantageous in anearobic operation. For long distance pedalling alone is most efficient and will give the best result.

The method of glassing over foam is more difficult than flat panel construction and the resulting boat will probably be better using flat panel.

You can find some interesting reading in this thread:
http://www.boatdesign.net/forums/boat-design/pedal-powered-boats-23345-20.html

Rick W

[spidennis]

Rick,
your boats are absolutely fantastic! when I started seeing your boats here I knew I was in the right place!

with all the talk on props, and the number of boats built with it, I'll have to give that a try, but for a few of my requirements I can see where the mirage drive might have an advantage, for me at least, right now.

For one, it's already built, no engineering on my part needs to be done. I make the mounting well and install it. No welding, no fabricating (I don't yet do any welding, yet being the operative word!).

Two, it's shallow draft. very important on the texas water safari, the adirondack 90, and around my local waters where I have to beach a lot. I position the "wings" so that they are flush with the hull bottom and use the paddle, when I have to.

when a friend first bought his hobie kayak with the mirage drive i though it was a silly toyish contraption until I put my feet to the peddles. I put the paddle down right after that! the same could happen if I got prop drive boat?
50 vs 85 percent difference?

rick, that link you provided I got into yesterday and still not thru it! good stuff in there, big time good stuff! You do realize though that my first prop drive boat will be heavily influenced by your designs? they'll be a big, big difference though, your boats look good!

I can't wait to try out shaping my hull designs in sand. It's really hard to describe hull shape with mere words, but I hope that with a few pics I can show what I got going on.

I still need specifics on foam, mat and glass though .... possibly some of the local surfers and boat builders might be able to help me out? yeah, I got a few trips to make, time to make a few visits huh?

50 vs 85 ...... that's haunting me ..... you've built a fair share of boats, along with the others here .... that's got to mean something .... am I already at a turning point? .......

[Guest625101138]

If you want to be competitive against kayaks rather than just compete then the best boat will be something like my current designs. The annual river race that I do has deal with logs and sand bars less than 1ft deep. My curved shafts handle this.

Did you follow this thread in your reasing:
http://www.adventuresofgreg.com/HPB/2008_09_15_archive.html
The build is discussed in earlier part of the blog but it is not the easiest or fastest.

If you are serious you should only consider carbon fibre. I would go for flat panl construction. It results in a quick build. You will build a whole boat with a gearbox for the cost of the Hobie flappers I believe. Last I heard they cost about USD800 but they have since reduced.

Don't believe the sales hype with Mirage. You will only ever see them demonstrated side-by-side paddles in pulling. There have been a couple run in the Murray Marathon and they are a joke from a competition point of view. My prop set-up is more practical in shallow water and weedy areas.

My last boat V14 does not have a weld in it apart from the prop but I could use a Bolly carbon fibre prop that gives around 80% efficiency instead of my fabricated prop.

Rick W

[spidennis]

rick, you really got me thinking ...... and now all my idea are up in the air, again ...... so what's it like to portage your v14? On the Adirondack 90 Miler there's some portaging to do, one is a real beast. It's 1.25 miles, starting up a knarly set of steep rocks, then levels out to some up and down uneven and rocky parts with stream crossings, then a long down hill part, again pretty uneven. I've done this with a plastic two man kayak that weighs 70 lbs and for the downhill sections I had wheels that made it easy, but I had to tote it on my shoulder going up the tough parts. On the v14 I'm not sure on where to even grab a hold of it to tote it short distance ....

[Guest625101138]

V14 can be built for less than 20kg (44lb). Greg got CP2 down to 18kg but it was pared to the bone. He did not use a shaft strut. He used a 1/4" shaft. I use an 8mm shaft.

With the rudder and prop set up I use the boat can be set down on the ground without risk of bending anything. This makes it easier to transport - could be slid if required but would suffer scratching on rocks of course.

V14 balances very nicely in one hand lifting by the drive frame just in front of the seat. However for long distances it is easiest to just carry on the shoulder.

V14 is 1.2m shorter than the V11 series boats and this makes quite a difference in ease of transport. The outriggers are best transported folded up over the seat although on V14 I have them plug in so they do not fold.

I expect if you constructed using 200gsm cloth over 6mm Corecell you would get a very nice, light hull. V14 took 38 hours to make the hull in actual work time. You need to allow time for epoxy to cure. The outriggers take almost as long and are good practice for the main hull.

I am not familiar with the the races. If you have rapids I think this might be an interesting challenge because you will need about 18" of water to run a prop or even use the Hobie flappers. You can have the prop bounce over things but you would not want this to be the continuous mode. You also need to be aware of heavy impact on the outriggers. It took me a while to get a boat that worked well in the Murray. Logs are the big issue there. If you did not see this then it might give an idea of how V11J goes in competition with an early model engine:
http://www.boatdesign.net/forums/attachments/boat-design/28050d1230859349-pedal-powered-boats-mm_2008_rw.pdf
You will see how the outriggers fold up for transport. This boat is noticeably heavier than V14 but I still carried it unaided on all but the last day when my wife helped me carry it the 500m to the start line. In that condition there is an extra 3kg of water and food that tips over the scales for easy portage for me. It would be up around 30kg. One condition of her being the support crew was that she did not need to do anything with the boat - just meet me at the end of each day and enjoy leisurely shopping, visiting wine cellars and long lunches. Low weight was a high priority for V14 and the method of construction aimed at achieving that.

Rick W

[spidennis]

I'm not sure the v14 will be able to do the beginning sections of the texas water safari as it might just be too wide of a boat for the narrow river sections. also steering could be a problem in the rapids and it might require a front rudder for quicker steering?

some pics of some of the rapids are here:
http://sports.webshots.com/album/563807230gbyyLo

If I can portage the 1.25 miles on the adirondack 90 miler the v14 might do good there. I wonder how wheels would work out on it over rocky trails?

I've also considered that around florida race. they have a 40 mile portage that requires a bicycle to tow the boat. since this v14 is already part bike, or possibly another design as you're basically camping out of your boat for a month, some even sleep in their boats .....
http://www.watertribe.com/UltimateFlorida/UltimateFloridaOverview.aspx

the bottom line is I guess one boat won't do everything, kinda like motorcycles. and now that my brain is scrambled I gotta regroup my thoughts ....
I'm still thinking a seakayak-ish boat but with your drive system instead of the hobie mirage drive that I can also use paddles with might be a good all around boat for the different bodies of water i'd be paddling in.

[Guest625101138]

For those conditions you would really want a folding prop. I think you would inflict a lot of damage on the Hobie flappers. Has anyone tried a Mirage drive in the event?

I have dipping rudders that work reasonably well. I have them on levers now so they can be applied quickly. They are out of the water most of the time.

You would also want to beef up the bottom of the hull to take the wearing over logs.

You lose a lot of speed if you make the boat wide enough to be stable without outriggers. There is another idea where you have trimaran configuration at the surface but a mono underwater and mono above the water. Trouble is this starts to get heavy.

Rick W

[spidennis]

ok rick, you're keeping me on track, thin is fast! so how do I make the v14 design do what I need it to do?

quicker turning (for texas water safari) and portaging (for adirondack 90), and a bit of storage for overnight
training/camping, a prop that can be raised to protect from (small) rapids, and can I use a kayak paddle as a backup?
(and when going thru rapids when the prop is raised) and if I feel crazy enough, that 40 mile portage for around florida race,
can I turn the kayak into a self propelled wheeled vehicle? (with enough storage for days worth of supplies?)

for those following along, this is rick's website:
http://www.rickwill.bigpondhosting.com/

He's done homework, he's proven his designs with results, so it only makes sense to follow success!

http://www.sandslave.com/v14/V14_Side_Viewb.jpg

http://www.sandslave.com/v14/V14_Port_Bowb.jpg

[Guest625101138]

ok rick, you're keeping me on track, thin is fast! so how do I make the v14 design do what I need it to do?

quicker turning (for texas water safari) and portaging (for adirondack 90),
V14 turns reasonably well and could be better with bigger rudders. I would recommend the dipping rudders but there are some minor improvements.
and a bit of storage for overnight training/camping,
There is a lot of space in the hull and it has quite good reserve buoyancy. You would need a hatch that can be put in the deck to get access. These are available.

You would need slightly larger outriggers and these could be mounted closer to the hull to reduce beam. Folding up would be easiest for transporting. If large enough they would enable a hammock of sorts to be set between the iakos.

a prop that can be raised to protect from (small) rapids,
I have used a pull cord to lift the prop on other designs. I will be making a folding prop soon and I expect this would be a good choice for the rapids. It is best if you do not need to worry about lifting it.

and can I use a kayak paddle as a backup?
Paddling in a recumbent position is not easy. You might want a foot well but this becomes a place that traps water.
(and when going thru rapids when the prop is raised) and if I feel crazy enough, that 40 mile portage for around florida race,
can I turn the kayak into a self propelled wheeled vehicle? (with enough storage for days worth of supplies?)
I remove the prop shaft on V14 for transport. It takes less than a minute if you use pins. Take some engineering to set up fold down wheels.


You would need to set down the requirements and concentrate on getting something to test that has the ability to expand to the ultimate boat. There is nothing like experiencing the conditions to determine the challenges.

Rick W

[Guest625101138]

You should start a separate thread for the Adirondack Challenger (or whatever) and use it to build ideas. I can give you a hull design to suit your capability. V14 is optimised for 11kph at 130W - my rated continuous output.

Rick W

[spidennis]

oops! I totally hijacked this thread! sorry about that ..... I'm starting up my own thread now ........ if the mod wants to he can delete my tangents ....