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Happyness is \pedal boating

Rick
I have been playing with pedal boats for over 7 years and had the following;
2 cats; 1 proa and a canoe all of which have been propelled by twisted chain drive units.
On my present project I cribed the flat sided construction and the total drive systen from your V14, but mine is shorter at 4.87 m, narrower at 0.210 m and lighter at 28 kg but I am sorry to say a lot slower.
The transon is flat for 2 reasons,

Ease of lifting onto my car roof without tipping sideways when balanced part on the ground and on the roof.

I read a small article in World of Waterbiking, that I thought sugested flat sterns virtually enlarged the boat and give a smoth flow behind the ship.
This can be done on streamlined shapes for airflow so I was intersted to see if it worked for water.
On the river I use, the current can be fast at times and I think the prop measurment system is quite good and I have been using this for 5 years.

Dennis

 

Dennis
My V14 boat weighs 22kg.

The V15 design I am building for my sister is 5m long. It will have slightly more drag at 11kph than V14 but should actually be a bit faster at full power because I have made it narrower.

From the photos on the ramp it looks like your stabilisers are immersed all the time. If this is so then being so short and heavily loaded they will add tremendously to the drag. They will not provide much roll resistance either because their waterplane area is quite small.

The best shape for the stabilisers is a long narrow flat bottom with pointy ends. I give mine a bit of rocker in the bow so they lift a bit when going through waves. In calm water they should be set up to skim the surface when the boat is loaded. This gives the highest roll resistance with least drag. Your V-bottom means they have to have a good deal of surface immersed before you start to generate much roll resistance.

Your boat should be able to get to 10kph without much effort and possibly 15kph or more depending on your power output in a sprint. The stabilisers will not have any wake when set right. If the transom of the main hull is submerged at all it will cause considerable drag.

 

possible steel flex shaft material

I built another flex shaft from a cut section of 3/16" electrician's flexible drill and am impressed with its strength and flexibility. The drills are available up to 72" and 1/4" diameter just about anywhere. This is excellent almost indestructible material, stiff enough for my low power strutless applications but may be too flexible if used without a strut in HPB. Here's an example:

http://www.mytoolstore.com/ideal/ide14-12.html

Porta

 

Vic
That is what Greg ended up using on his copy of V11A but he used 1/4". He could not get hold of lengths of spring steel.

I always use the strut for normal mucking about. Greg operated well without a strut but the hull is very easily driven.

I find 1/4" a bit rubbery at higher power with 1:4 gearing so prefer 8mm. 3/16" would need to be geared higher than 1:4. To use 8mm means I have to increase shaft length to increase the curve radius. The torsional rigidity is a function of diameter to the 4th power so a small increase in length to allow the extra diameter provides big gains in the system torsional stiffness.

 

Out Rigger Performance

Rick
Your comments on the outriggers are appreciated & will be followed up.I have built is the ability to raise up the outriggers in stages by up to 70 mm.
The V bottomed out riggers were existing , left over from my failed proa project. I was interested in their performance as they had a similar sectional shape as the ouriggers on the cardboard Icarus boat by Mark Battley which was one of the first outrigger stabilised slim HPB to have a good performance.

Dennis

 

Dennis
The outriggers can be built light as they are not supporting a large load. My new ones use 100gsm cloth on 3mm thick foam. They are 2m long and weigh 1.2kg. I could not stand on them if they are on hard ground but they can be handled roughly and not suffer damage.

I have a friend here who has made his with 3-ply and they are more than strong enough.

The shape is simple to make with 4 strips of ply and some 1" thick blue polystyrene foam for 3 bulkheads. Mid section is 100mm wide and 150mm high.

 

Ebay auction for Mitrpak

Hello all,
I am a new member but I have read up quite a bit on HPB's. I will make the first cut on a plywood 24 ft outrigger canoe project on Friday. I am going to use sail power primarily but do not want a gas motor for extra power. I plan to use it for a cruise up the Columbia river in the U.S. and if that goes well then some Mississippi river fun.

I have read the entire thread but have a few questions. First, will this gearbox from this http://cgi.ebay.com/MITRPAK-GEAR-BO...tem&pt=LH_DefaultDomain_0&hash=item27aea8037c e-bay auction work? They also have an HAR 10 137465 R-2. I can not seem to find them on the Mitrpak website.

The second question is with regards to flexible drive shafts. From what I understand the flexible drive shaft would connect to the gear box which would turn the propellor. How does a spring steel or aluminum shaft work? Does it just rotate and spin the propellor?

Thanks for any help,
Rustin

 

The number does not look standard. There is no indication of the ratio. The R-3 might be 3:1. It really does not matter other than the input gearing you will require to get a suitable shaft speed. It is a good price. Including postage it is less than half a new box of this size. The box is bigger than you need so a little extra weight.

The curved shaft is mounted to the box and prop. You have to set the curve on the shaft to ensure the shaft has infinite fatigue life. This means the shaft will be operated well below its yield point. Hence there is no perceptible loss in the shaft due to the forced curve because it operates in its elastic range.

The allowable radius depends on the material you can source. Spring steel is the best apart from the need to protect it from corrosion.

 

Thanks for the information. I am going to go ahead and order one. Since my shaft is going to be spending a lot of time in the water would it be better to just get a sealed flexible drive-shaft like the kind that goes onto a drill? Again thanks for taking the time to answer.
Best regards, Rustin

 

Rustin
I expect you would find a sealed flexible shaft would feel very rubbery. You need to check the torsional compliance. If the shaft has a lot of compliance it winds up on the power part of the crank and then unwinds through the deadspot on the crank. It is like trying to pedal in mush. There is absolutely no notion of coasting. I know the values of compliance that give reasonable feel for various drive ratios.

You can use stainless steel but the allowable curve radius is much higher than spring steel. There are various ways to protect the shaft from corrosion.

If you post a few sketches of what you plan to build then you may elicit some useful comment.

 

I don't use a rear skeg with my flex shafts, and if that is the way you will be running your boat, YES it simply rotates and spins the prop. The prop self adjusts to the horizontal with a variable curvature as allowed by the longitudinal stiffness of the shaft and thrust of the prop. I believe Greg K used an unsupported flex shaft in this way when he set the 24 hr hpb record.

Porta

 

Well, I just bought one of the units. I see that the seller sold a second one to another buyer for 55$. I will report back on the condition when it arrives.

Portacruise,
I will not be using a skeg. If the shaft is as easy to take out of the water as some of the videos on this thread suggest then I will have some sort of bracket to keep it out of the water when I am using sail power.

Rick,
I re-read about some of the issues with mush-like feeling that the flexible drive shaft can produce and feel like I should find some spring steel. When I searched for it I found some pretty long spear fishing bolts made from spring steel. From reading the thread it appears that 8mm is the way to go. I may be wrong, but does the length and degree of curvature of the shaft depend on the boat dimensions?

I have found a website that shows the exact plan for the boat I will build. It is here http://homepages.paradise.net.nz/garyd/24TackingSail.pdf
I purchased a book from the designer that has some more detail. I plan to build it then incorporate the pedal drive into it. The rear section will be where I intially plan to put the pedal unit. There will be a lot of leeway with regards to decking and bulk head support, so I can mount it on the rear deck or inside the rear compartment. If it is inside the compartment I may have trouble with visibility and that is why I think it needs to be built first.

I start my summer break on Thursday afternoon and will have over a week before the begining of summer school to work on the build. I plan to have most of the boat done except the 'glass before I start the summer session.

Thanks again,
Rustin

 

The allowable curvature for infinite life depends on shaft diameter and the fatigue limit of the material. If it is good quality spring steel then you can curve as tight as a 3m radius.

So you need to layout a curve with 3m radius with you prop blade tip at least 50mm below the surface. The larger the radius the better margin you will have. If you go as low as 3m you have to set the gearbox shaft and strut at exactly the right angle and position relative to each other. Going to a larger curve gets more tolerant.

An 8mm shaft up to about 2.5m long feels OK working at 4x cadence or higher.

The logical place to locate the shaft from a thrust line point of view will be down the port side of the main hull as this will roughly be the centre of drag.

I think you would find the boat easier to operate with a proper rudder than the makeshift with the paddle. Otherwise it is not too bad. I prefer twin outriggers to a single outrigger because you can set the outriggers to have no drag when the boat has no roll.

 

I just recieved the unit in the mail. It is in great shape. It looks and feels like it had very little use. I had an untimely truck repair that dipped into my boat budget and it looks like I may not make the first cut until late August. I bought a 10 dollar crawfish trap and will be fishing for the next week until my summer semester starts. Not an equal trade-off but fun nevertheless.

I originally thought that the twin outriggers were the way to go. There is a plan in the book that I have that already incorporates them into the design. In addition to that I already have a large supply of foam core that I was able to procure for free with the idea of using it for the amas for this boat. Then I got a surplus windsurfing rig. I wanted it for the mast and sail. The board itself is useless to me but in good condition. I was going to cut it up and glue the outer edges together to make a single ama and thus the idea for the single outrigger came about. I am now thinking of how to get two seperate amas out of the board by using the edges as the downward facing part and then using my surplus foam core to shape them up.

 

I would consider what the best shape for the ama would be before letting its shape be dictated by something you have that might do.

I expect that you will want to use your body to counter the sail moment. In this case I would be considering an ama that is long and slender with a flat bottom section having slight rocker in the bow. This provides good initial stability without much immersion and then develops dynamic lift at speed.

I would have them almost as long as the main hull and have the bows of all three hulls aligned. The amas would be set higher than the waterline of the main hull.