Unless they are stainless steel then chains and chain sprockets will rust when exposed to salt water.
The motor is most efficient when it is delivering its power at high RPMs. If the motor is lugged and put under a heavy load at low RPMs then its efficiency declines and much of the power that it consumes is turned into heat instead of output shaft power.
If you are interested in special ordering a gear motor with belt pulley, or if you have any furher question, then please let us know.
11mm OD with a 4mm wide x 2mm deep keyway is the shaft size for both 350W gear motors. This is the part of the shaft that the sprocket or pulley fits on and there is a larger diameter shaft section behind the 11mm section, and a left-hand 8mm threaded shaft section after the 11mm section. The 350W motor with chain sprocket has a 9mm long 11mm OD shaft section, and the 350W motor with belt pulley has an 18mm long 11mm OD shaft section.
The sprocket on the 350 Watt gear motor is designed for #410 chain which is 1/2" x 1/8". #41 chain is 1/2" x 1/4" so it will work with the #410 sprocket, however, there will be a little side-to-side play between the sprocket and chain which is usually not a problem especially in slow speed applications.
Regarding our 36 Volt thumb throttles, THR-68 has a battery level indicator and does not have a switch. THR-136, THR-137, and THR-138 have a battery level indicator and a latching switch. THR-138 has 2.8mm male terminals which are compatible with the throttle connectors on our controllers.
Please let us know if you have any questions.