I tested my human powered boat 6 days ago. It’s powered by treadles oscillating a fishtail. Well, why be conventional? It was dismally slow but on a positive note it didn’t leak at all. As a Consequence of this I’ve done some modifications. I increased the size of the fishtail by about 350% to get more leg power into the water. I also upped the size of the rudder but feel that the main enemy to steering had been my lack of speed. I rebuilt the wheels I use to lug the boat down to our 127 mile long waterway and was ready yesterday though short of time. So today, after walking the dog, it was time for my second test.
It was mainly sunny as I made the 0.7 mile journey to the water and the wheels were working well. I lacked the stomach churning nervousness of my first attempt. I may even have been excited! As ever since lockdown there were plenty of walkers on the canal bank and I chatted to a few as I prepared to launch. I even had a few compliments about the look of the boat, which was gratifying. I climbed onboard without drama and pushed off. I treadled gently and was again met with little in the way of forward motion. I realised that I wasn’t moving the treadles through their entire arc of motion so gave a bigger push. Now I was moving, though still quite slowly. “I’ll see you in Leeds”, quipped one observer.
The boat was bobbing under power and didn’t seem any faster if I treadled quicker. There seemed to be a sweet spot where I made the most progress. I could turn well enough initially but as the boat slowed in the turn I was unable to complete a u-turn. It was simple enough to use the paddle for this. I also notice that the fishtail was catching the rudder, which hadn’t happened in the garage. I decided to ascertain my speed, however disappointing. I could already tell that walkers were faster than me, so it must be less than 3 mph. I started Strava as if I was on a bike ride. There is a canoe category but I didn’t know what information it would provide so I stuck with the familiar. After a few loops I was noticing that the right foot treadle was much stiffer to press than the left. This seemed wrong since the left treadle lifts the mechanism whereas the right has the assistance of gravity. I was feeling confident and relaxed on the water, with still no signs of leakage but had gathered all the information I needed from my test so I climbed onto the bank and hauled out.
By remarkable coincidence the engineer who I spoke to after my first try walked by, this time with his wife. He asked me how it had gone and I gave him a brief rundown. I said I’d like try a larger up and down movement of the tail and he pointed out that this might cause more bobbing of the boat, which he’d noticed it was doing. I noticed that one of the stops which control the angle of the fishtail in the water had bent and said that this can’t have helped. Shortly I realised that my thought was wrong. It was surely the bending of the component which had given me some speed and made the right treadle so much more effective whilst the left did little. That’s it. I need to allow the fishtail to achieve a bigger angle than I’d originally set, at 15 degrees from horizontal. I measured the angle where the stop had bent and now the tail was giving 30 degrees.
My next changes are obvious and I thought about them as I pulled the boat home in a happy and relaxed state. Ideally I’d like to be able to alter the tail’s angle of attack whilst on the move to find an ideal figure. I need to do some design and construction of a mechanism for this or at least to allow easy adjustment by lifting the boat out. I’m now far more excited about the boat’s future but what did Strava reveal?
The peak to the left looks like a GPS error but a little later I reached a speed of over 2 mph. The maximum hull speed of my boat is 4.2 mph without it planing and skimming across the surface so over 2 mph on a second test looks good. Tomorrow I hope to ride the mountain bike. Life is good.
Mountainbiker 