A motor assembly includes a structural unit for mounting a motor, for mounting and enclosing electronic circuitry, and for providing a corridor for air to flow and cool the motor and/or the electronic circuitry. The motor assembly includes a substantially water-resistant motor that rotationally drives a fan for cooling the motor and/or rotationally drives a propeller for providing propulsion to watercraft. The electronic circuitry of the motor assembly receives and transmits instructions to a command post by way of electronic signals and distributes power to the motor. The structural unit seals the circuitry from the surrounding environment.