Ashley, I think our friend is talking about a petrol strimmerlike the council men use cutting down the weeds at the edge of playing fields. I had a friend down in Cornwall who fitted one in a model boat which was then powerful enough to tow a rowing boat with four people in. What he did was to chop the drive shaft and expose enough of the inner shaft to cut a thread in, then fitted a prop between two sets of locknuts torqued right up. set free of its load, the model flew over the water as it had a planing hull, you know the picture, a boat balancing on the tips of its propeller with occasional excursions down to the water making lotsof wake. Thinking about it, it must create the sort of problems like a racing car clutch, can your universal joints carry the torque ? and is the propeller going to tear itself out of the hull ? I have visions of the model doing a bluebird as the bottom half is going quicker than the top half, and could easily overtake or undertake to be exact. The beauty of that motor was that it had the pull cord starter. My son has a pair of IC racing cars for his children, and recentlytook one of the cars down our road for his daughter to play with, that engine had a pull cord starter, and sounded like a ferrari formula one car coming down the road at max chat, I remember thinking, that would be ideal in a boat as long as it had an efficient exhaust to get rid of the oilthat went straight through the engine without igniting, but you were right Ashley electric is much more efficient, and as an electronics technician I am more at home with it, I can’t see me running an IC boat in the bath, which is what I do to check waterline for ballast etc. She who must be obeyed would go ballistic.