[Bushwacker]

Connor's right - it's all about torque. Years ago Chrysler and Evinrude used to make "sail drive" models of about 6 hp similar to his Yamaha with lots of gear reduction and big slow turning props. Too bad they don't still make the old British Seagull. Very simple (some would say primitive) with exposed flywheel and gas tank (looked like a 1930's vintage outboard), no recoil starter, but very light (maybe 30 lbs) with LOTS of torque. Lots of brass and nickle and virtually indestructible. My neighbor had a 5 hp model, with a 5 blade prop about 10" diameter with about a 5" diameter hub and lots of gear reduction. With that thing on his dingy, he could TOW his 20 TON 42' Wheeler sedan cruiser! But I'm sure it wouldn't pass emissions laws and OSHA would go nuts with an exposed flywheel and starter rope!