OTF
Coney Island Whitefish Biologist
First of all - be VERY careful about safety with these, a scooter switch stuck in the "on" position can be extremely dangerous, dragging a diver up or down uncontrolled. Carefully consider a very reliable switch mechanism, or some sort of redundant killswitch. Runaway scooters can and do bend people.
If I were going to DIY a kickass scooter on a budget I would poke around for a GOOD deal on an old (dead?) past generation scooter, one of the large ones meant for lead acid batteries like a Farallon. That provides a cheap well-engineered housing and prop. I would replace the electronics with a large modern brushless motor, ESC, and LiFePO4 batteries with onboard BMS (or power tool batteries). Similar setup to an ebike. Make sure any penetrations, shaft seals, and o-rings are replaced and reliable.
Marinizing a big brushless motor and running it wet is also an option, and eliminates the shaft seal. Wet running brushless motors have a lot of advantages, though encapsulating the rotor and stator properly is nontrivial. Bearings, shafts, and hardware need to be swapped for corrosion resistant materials.
If I were going to DIY a kickass scooter on a budget I would poke around for a GOOD deal on an old (dead?) past generation scooter, one of the large ones meant for lead acid batteries like a Farallon. That provides a cheap well-engineered housing and prop. I would replace the electronics with a large modern brushless motor, ESC, and LiFePO4 batteries with onboard BMS (or power tool batteries). Similar setup to an ebike. Make sure any penetrations, shaft seals, and o-rings are replaced and reliable.
Marinizing a big brushless motor and running it wet is also an option, and eliminates the shaft seal. Wet running brushless motors have a lot of advantages, though encapsulating the rotor and stator properly is nontrivial. Bearings, shafts, and hardware need to be swapped for corrosion resistant materials.