I know it sounds like something a few guys thought up after a six pack or three. But its true and its real, I just saw it on TV! It is a device that fits into a well in the middle of the (in this case fibreglass) canoe. About 18" high, perhaps 8" wide and maybe 12" long. Inside was a vertically mounted electric motor with a whopping 680 Watts of raw power attached to an impellor and a downward angled (25 deg?) and rearward facing exhaust. The unit did not protrude below the canoe. Weight is 11kg not including the battery. Cost $1200 of our folding.
The show is one where people show their "inventions". The inventors come on and answer a few questions from panel. The lady on the panel asked "If the unit goes through a hole in the bottom of the canoe, how come water doesn't come in?" The answer was that "The unit goes in a well, and that the water level is higher outside the boat than in the well! Its just physics." What the?