Modifying my boat.

My homemade, pedal powered boat took a long time and many incarnations before I was satisfied with it. I tried 4 different propulsion systems before I found one which propelled me at a satisfying speed. I then only needed to strengthen it for reliability and I had a boat which I could cruise around in without every trip being a test of some new addition. I could now travel for a few miles, taking over an hour and use the boat as a form of exercise. The experience was, however, rather different to riding a bike. The resistance of the water was preventing me from turning the pedals at any rate much faster than 30 rpm, compared to cycling where, to get good performance, you’ll turn the pedals 60-90 times per minute. I started to think that this was pedal boating and that I couldn’t improve matters but after a couple of recent trips I became anxious to make the necessary alterations. Sailing was very stressful to the leg muscles like a weight training exercise but barely raised my breathing beyond what I’d experience whilst walking. I believe that I’ve been powering the boat using fast twitch muscles. These muscles are used for sprinting, power lifting and the like. They barely need oxygen to fuel them whilst in use unlike slow twitch muscles which are used for endurance sports like marathon running or long distance cycling. In these exercises you’ll breath much harder to provide sufficient oxygen for the use of the muscles. I expect that by increasing the rate at which the boat’s pedals turn I’ll transfer the power input from fast to slow twitch muscles which will cause me to breath harder but give much improved stamina before fatigue sets in. The boating experience will then be far more like my usual sport of mountain biking, at least in terms of the way it uses the leg muscles.

The pedals had been attached directly to the paddle wheel with long rods so that both elements turned at the same rate.

The previous incarnation, which was close to perfection but not quite close enough.

What I needed to do was to introduce a way to change the rate at which the pedals turned compared to the paddle wheel and a chain and sprockets seemed sensible. I didn’t, however, want over 4 meters of greasy flailing chain running the length of the boat so elected to still use the rods, now shortened, to turn a layshaft which would take the power to the wheel via the chain and sprockets. I fabricated the layshaft and brackets to then fit inexpensive mountain bike sprockets and a rather groovy gold chain which, whilst cheap, looks good.

Adding the layshaft has allowed me to push the rods further out to give more shoulder room and I added a chain tensioner made from a piece of nylon rod which has laid around for the past 20 years waiting for such an occasion. I took the boat to the canal only to find that the chain came off quickly. I knew I needed to make some chain retaining devices which I’ve now constructed. I would have tested today but after showers and a surprisingly tiring carpet laying exercise in a small bedroom it will have to wait until tomorrow.

The pedals are very simple. I’ve called the boat “Perseverance” to acknowledge the perspicacity and perseverance which the build has demanded. If all works satisfactorily then a splash of paint and I’ll be finished.

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