Originally Posted by 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 ? 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.