Paddle Drive for a kayak

[SteveP]

I'm looking for info about human powered paddle drives.

I'm considering experimenting with an enclosed shallow paddle wheel - a bit like a hybrid jet drive.

I need a shallow snag less drive for the Yak because we drag thru shallow gravel flats often and a wheel would be perfect . Also a wheel will climb over obstacles like limbs in the water.
Perhaps a two or three blade set up could just stop with no blades below the hull for shallow dragging times.

I'd like the smallest diameter wheel / paddle set up that could work even if I need to gear up for high wheel rpm

I'm thinking a 27 speed chain transmission off a road bike would perhaps make a good start as I have no skill in making the initial calculations, and perhaps just picking thru the range would lead me to sweet spots. Plus I have some and they are cheap !

I could quickly chop up a bicycle add some paddles to a 26 inch bike wheel and have most the rest of the work done, except mounting to a boat...


My initial question are:

- More paddles or less ?

- Would a wheel with three 4" x 4" paddles move enough water.

- Do paddle wheels work better at higher rim speeds ?

- Does it matter what happens to the splash, performance wise, because I 'll need to enclose the whole wheel

- Could a small diameter wheel work better than a huge diameter wheel.

- Could small paddles at hi rim speed work better than large paddles moving slower ?



thanks ! for any directions to videos and web sites !

-----------------------------

[Rick Willoughby]

I'm looking for info about human powered paddle drives.

I'm considering experimenting with an enclosed shallow paddle wheel - a bit like a hybrid jet drive.

I need a shallow snag less drive for the Yak because we drag thru shallow gravel flats often and a wheel would be perfect . Also a wheel will climb over obstacles like limbs in the water.
Perhaps a two or three blade set up could just stop with no blades below the hull for shallow dragging times.

I'd like the smallest diameter wheel / paddle set up that could work even if I need to gear up for high wheel rpm

I'm thinking a 27 speed chain transmission off a road bike would perhaps make a good start as I have no skill in making the initial calculations, and perhaps just picking thru the range would lead me to sweet spots. Plus I have some and they are cheap !

I could quickly chop up a bicycle add some paddles to a 26 inch bike wheel and have most the rest of the work done, except mounting to a boat...


My initial question are:

- More paddles or less ? 12 is a good number.

- Would a wheel with three 4" x 4" paddles move enough water. Of course but not very effectively.

- Do paddle wheels work better at higher rim speeds ? No.

- Does it matter what happens to the splash, performance wise, because I 'll need to enclose the whole wheel Any splash is wasted energy. If you make a jet wheel then it will be better to direct the jet backwards rather than upwards.

- Could a small diameter wheel work better than a huge diameter wheel. No. You need a good surface area to get good efficiency. 12 paddles about 1.2m wide by 100mm deep on a 1m wheel is a good size for a human powered craft. Immersion would be 100mm.

- Could small paddles at hi rim speed work better than large paddles moving slower ? No. See above.



thanks ! for any directions to videos and web sites !

-----------------------------

There are a number of threads that cover paddle wheels. Fundamentally they need to be large to get an effective result.

If you make a decent size wheel it will easily support the weight of the boat. Most human powered boats use a wheel on either side like the boats shown in this clip:
http://www.youtube.com/watch?v=-QjRM-cQpHw
You might need to replay the clip a couple of times to pick up on all the wheels shown but once you have, you will have a good idea of relative performance versus size.

Rick W

[billberit]

I have experimented with paddle drives for some time and have found they are more trouble than they are worth. The noise, and maintenance, especially in salt water, is a killer. Steering is another problem, and in a light weight craft like a Kayak, a real problem, since the drive unit is quite heavy and the mechanism is complicated. Steering by ore while peddling is a tough act. If you wish to pursue this, try a very small diameter wheel assemble with 5 or 6 blades to start. Each blade must be in the water no more than 50 percent of its height. More than that and it starts to act as a vertical pump. 25 percent if advised. Overall diameter of the wheel assemble should be as small as possible to keep weight to a minimum. Wheel speed is to be kept low to conserve energy and keep noise down from slapping. Materials can be sheet aluminum or SST, with all parts coated for salt and chemical protection.
I strongly suggest developing a really good propeller drive, since there none too many on the market. They are much more efficient and next to maintenance free. Plastic props from electric drives work well and won’t ware you out quickly.
It takes a lot to beat the efficiency per input and maneuverability of a good old ore!

[rwatson]

Try looking at

http://www.autocanoe.com

for a working example - may be worth getting plans?

[ancient kayaker]

-I wouldn't like to hve to peddle that along the road in the rain for too long!