First wet test

So.......first wet test on Saturday morning. Jane, myself and Kevin went to Cox Lake near Tantallon where we met Bill who had paddled over to help. We put the hulls and frame parts together without incident and then clamped on the boom with all the drive train, the seat, and the support tube that held the steady bearing bar for the prop shaft. We had the center of the main frame marked and positioned the assembly with the center of mass where we thought it should be. Right on the money, because when it was thrown in the water it was about 1 inch out of the water on the bow and stern. This was installed with duct tape, c-clamps, retchet straps etc!
I kept one rudder dry and installed a telescoping tent pole to the other with a ball style tie rod end. Since this was still not long enough we duct taped a paddle to the end of the handle.. Nothing but the best.....

The prop was an APC plastic model airplane prop ( 16 x 12) and I should have taken a picture of it before it went in the water. It is on the end of an 11 foot aluminum shaft, 3/8 in diameter, or just under 10mm.
52 tooth crank sprocket, to a 14 tooth sprocket on a 2:1 Miterpak right angle gear box.

The prop is installed on a stainless steel stub shaft which goes through a Delrin block. This is bolted to a 1.5 x .125 aluminum flat bar going up to the frame. This is what I wanted to use to set the maximum depth of the prop. All the joints used 1/4-20 bolts with self-locking nuts so they could all move without falling out.

The first thing I noticed was how easily the boat moved through the water. A very light effort with a canoe paddle would move it right allong. I started to pedal gingerly and everything worked great. However, when I used just slightly more effort I could hear the prop hitting so I went back to shore. Turns out that when pedalling, the bow in the shaft is very much exagerated and this effectively shortens the shaft which changes the angle on the aluminum flat bar. So we experimented with woving the hinge point forward but eventually ended up taking the guide off altogether. This worked great for about 10 minutes and while I was starting to push just a little, one blade snapped off the prop!! On examination we could see that the other blade was white and soft at the same location and it broke a few minutes later. by this time we were just using a loop of rope to lift the prop for shallow water. I really don't want the prop dragging on the bottom when I stop pedalling....

I think maybe the gearbox is just too far above the surface and the blades are working too hard to try and straighten shaft when pedalling. There was more flopping of the drive shaft than I expected but this could be due to not enough of the shaft in the water.

Over all I was extremely happy with the first outing and now will start the refinements!