designed for slow running cordless electric drills
mount m10 shaft in your drill,
screw drive shaft into propeller,
lock the propeller with 2x m10 nuts and you are ready to go
works fine for canoe size, SUP, etc
After several runs I added a wooden counter bearing block for easy steering with the second hand: One hand holds the drill, second hand close to water surface holds the wooden counter bearing for steering.
Just drill a 12 mm hole into the wood. For thoose who want to over-engineer this: add some ball bearings. :)
picture was taken while printing with 0.8mm nozzle and 0.4mm layer hight. this is really on the edge for the Prusa MK3 but prints in less then 3 hours!