What type of propulsor is typically used in electric motor driven, transverse, tunnel bow thrusters to limit the starting current of the single speed drive motor?

Correct Answer: Option C — Controllable-pitch propeller

Controllable-pitch propellers allow the drive motor to start under a no-load or low-load condition by setting the blades to zero pitch. This significantly reduces the starting torque and current draw, preventing excessive electrical stress on the ship's service generators during the startup of large transverse tunnel thrusters.