JEM Watercraft

Hi,

I'm contemplating building a Gander River canoe, but with the addition of pedal power to drive a small prop for a bit of cruising on the English rivers and canals.

The wineglass shape of the hull seems to lend itself well to the addition of a prop and small rudder at the back. The early questions that I'm wondering about are:

1) What's the best place to locate the propshaft, and how should it be built in to the hull? This will be affected by the choice of prop size, ie. whether to use a large prop/low revs or a small prop/high revs solution. I favour the small prop, as it will keep the draft shallow, and reduce the weight. I have a 25:1 gearbox which will spin a small prop at 1500-2000rpm based on a cycle rate of 60-80 per minute.

2) With the high seating position required for comfortable pedalling is the beam wide enough for stability?

The final plan is to have 2 sets of pedals, both facing forwards, with belts linking back to the gearbox hopefully enclosed under the rear decking, though this will depend on the final position of the propshaft.

Any suggestions as to how to do this thing are welcome, as I'm not a boatbuilder - yet!

wow, that's the most interesting question I've had yet.

There's a few concepts shown on this page that might be useful:

http://www.humanpoweredboats.com/Photos ... edHPBs.htm

My favorite concept is: http://microship.com/bobstuart/spinfin.html . I like that one the most because it does not require any sort of through-hull mounting.

As for best position to mount, I'd guess you'd want to balance the boat by having the majority of wieght at midship.

GRC can be built without the decks and bulkheads. So mounting everything right off the floor should keep you plenty stable.

Depending on how you mount it, keep in mind it'll be heavier and require deeper water to launch.

To keep CG low whilst under way, consider a recumbent position for pedaling. Could sit upright when you get to destination.

Thanks for those comments and links, some interesting ideas for the future there.

I think the best plan is to just get on and build it and then do the tweaking and trials. I'm pretty confident of getting a half decent cruiser out of this, but I'm sure whatever I do it'll need some upgrading over time.

A recumbent position is ideal for a low CG for sure, but as my physio pointed out this position is very poor for the spine, also with your legs in front you have to "carry" the dead weight of your legs on the pedals, as opposed to when you are on a bicycle when they are below your body. Final position will be a compromise, but 10-12" off the floor should be just about enough.

The final weight is very relevant as ideally I want one person to be able to get this boat out of the water, mainly so that it can be carried around the locks rather than queing-up and going through. Things can get a bit busy in the summer.

It's gonna be a fun project and I'll be back on this forum for sure.

Splash

Splash, I have to tell you two things. First off, I wish that you achieve success and obtain good fortune in this project. Secondly, if you do it will prove me wrong.

This type of design looks to me like it has "Rube Goldberg" written all over it. So, go ahead and prove me wrong. I'll raise a glass in your salute.