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

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

Gas turbines operate at extremely high rotational speeds, often exceeding 3,000 to 10,000 RPM. The main reduction gear is essential to step down this high-speed output to a lower, efficient speed suitable for driving a marine propeller, which typically operates at much lower RPMs for optimal thrust and cavitation control.