Question 333General Subjects - Assistant Engineer

The correct answer is D) Gas turbine. Gas turbines typically operate at high rotational speeds, often in excess of 10,000 rpm. To interface with the propeller, which requires much lower rotational speeds, a geared-drive system with a double reduction is employed. This allows the high-speed gas turbine to be coupled to the propeller shaft, with the gearing system reducing the rotational speed to the appropriate level for efficient propeller operation. The other propulsion modes (slow-speed diesel, medium-speed diesel, and high-speed diesel) do not inherently require a double reduction geared-drive system, as their operating speeds are more closely matched to the needs of the propeller.