Gary Thorberg, from Farmington, Minnesota, mounted a 3HP outboard gas engine on his W500 fishing kayak. His goal was to break the speed record for this kind of watercraft, and he did it, big time, clocking 9.6 mph. Interestingly, there was no difference between upwind and downwind, which raises the possibility that Gary simply reached the upper limit of this motor’s speed, which is set by factors such as RPM, propeller size, pitch, etc.
9.6 mph is over twice the W500’s hull speed. Hull speed (a.k.a. Froude Number) is a constant number that increases relatively to the hull’s length at waterline. In other words, it’s harder to make shorter boats go at higher speed than it is to make longer boats to go at high speed.
Gary’s W500 was planing.
In comparison, here is a quote from an article about dinghies outfitted with outboard motors:
“Another option is an outboard motor. Two horsepower per meter can reach hull speed. Ten horsepower per metre will put a flat-bottomed dinghy on plane. A 10-foot (3.0 m) dinghy with a hard V-bottom hull and a fifteen horsepower outboard can reach speeds of 25 mph (40 km/h).”
To put things in perspective, the W500 is about 3.5 meters long…
NOTE: This video shows an experiment, as part of a research and development (R&D) effort.
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