The purpose of the main reduction gear in a marine gas turbine propulsion installation is to _________.

Correct Answer: Option B — transfer high-speed gas turbine rotation to low-speed propeller rotation

Marine gas turbines operate at extremely high rotational speeds, often exceeding 3,000 to 10,000 RPM. Conversely, marine propellers require significantly lower speeds for efficient cavitation-free thrust. The reduction gear serves as the mechanical interface to step down these high turbine speeds to the optimal propeller shaft RPM.