Weight, efficiency, range, etc.
Posted by: guideboatguy on Nov-20-12 12:34 PM (EST)
If weight, efficiency and range matter, then there is no other choice except a small gas outboard. If cost enters into the picture (as it often does), then electrics have the advantage, at least in the short term, though I'm not sure about how the cost of gas versus batteries compares in the long run. I just did a quick check and found that a 4-cycle, 2.5-horsepower outboard motor from Mercury weighs less than a deep-cycle battery having moderate capacity. I didn't see a two-stroke motor of that size, but if you can find one, it will weigh less. Compared to the weight of a battery plus an electric motor, the weight advantage of the gas motor is huge. The weight advantage remains even when carrying several days worth of fuel, and of course, several days worth of cruising can't be done at all with an electric. A small gas motor will be much faster, which if you plan to go far, might be important. Finally, small modern outboards are amazingly quiet.
That said, most people choose electrics, I think mainly for the low cost. Just don't forget that the law requires that the battery be not just covered, but securely attached to the boat so that it can't move. Then remember that the weight of a battery and electric motor might be more than the built-in flotation of your boat can carry, meaning if you ever tip over, you lose everything. Extra flotation might be a good idea.
Also, too much power that's suddenly applied to make a sharp turn can roll a canoe right over, especially if done at slow speed, so with a gas engine it can be necessary to use some common sense. You'll also need a good mounting system for either type of motor, but it's probably more important that the mount be sturdy with a gas motor.