Pedal powered dinghy works at last

[alan craig]

I calculate that you should go about a knot faster with plain socks
This is a great project and you clearly want to stick with it. My suggestion is to buy a used 16ft. open canoe or possibly tandem kayak and cut off the last 3ft. Then make and fit a transom to the new back end and transfer your technology to what would be a much more suitable hull. Allow for a slightly larger diameter paddle wheel in the future.
I have a sawn-off bicycle frame for a pedal boat project but it will have to wait until I stop messing around with li-ion batteries and solar charging.

 

[Andrew Kirk]

Actually my mind has turned to a pedal powered paddleboard! I mean, why not? It could be used in surf or other less calm waters. The socks are an important part of the project.

 

[portacruise]

Maybe a good way to cool off during the hot summer?

 

[Andrew Kirk]

An update on my boat.
Training by boat. https://mountainbiker.online/2021/09/02/training-by-boat/

 

[Andrew Kirk]

Development of my boat has continued apace! I found that it was to "high geared" and I could only turn the pedals around 30 times per minute, which is way too slow for a cyclist. To improve things I've added a chain and sprockets into the drivetrain to enable me to turn the paddlewheel at half the rate of the pedals. After a few attempts I've got it all working correctly and now think it's about as good as I'm going to get it. Yes, I know a longer, slimmer hull would give me more speed but as a bit of fun on the canal speed is not so important. Stability is good and I think I could now contemplate a longer trip, like 10 miles.
https://mountainbiker.online/2021/10/10/a-boat-based-workout/

 

[clmanges]

@Andrew Kirk , I don't know why anyone hasn't suggested this before, but I think you can make your paddlewheel more effective by adding sides to it. Flat plywood rings, the outer diameter being the outer diameter of the paddles, and the inner diameter being the maximum depth of immersion of the blades.

As it is, when a paddle blade enters the water it's pushing some of the water backward but letting quite a bit of it out the sides.

Can someone else confirm this?

 

[Andrew Kirk]

The crazy thing is that if I calculate the tip speed of my paddlewheel it goes......diameter 0.8 meters X Pi = 2.513 meters. If it turns in 2 seconds then that's a speed of 1.257 m/sec or 2.81 mph. Now the gps app. Strava may tell me that my average speed is 3.5 mph but this is not true. Measuring the distance travelled using Google Earth and knowing the time informs me that I tend to cruise at 2.6 mph. Not so different to my paddlewheel tip speed.
I'd be fine with this and call it efficiency but thinking a little more about it it's not just the tips of the wheel that contact the water. About 12cm of blade is in the water so at this point the paddlewheel speed is only 1.968 mph! Am I defying the law of conservation of energy? I doubt it!
I've wondered if my flat transom is dragging the water along behind it which could explain my figures but whatever the explanation I'm happy that I can reach hull speed in a sprint and cruise at two thirds of this figure. From my cycling experience I'm guessing that my energy input will be less than 200 watts at a cruise.

 

[portacruise]

Here's an interesting paddle design that goes way back, with very good portability, and simplicity, if it could just be made drier....

 

[clmanges]

Here's an interesting paddle design that goes way back, with very good portability, and simplicity, if it could just be made drier....

I'm not sure the wet ride is a bug. It may be a feature.