If the speed of the propeller is 135 RPM, the speed of the engine camshaft shown in the illustration will be __________. Illustration MO-0003

Correct Answer: Option A — 135 RPM

Standard four-stroke and two-stroke diesel camshaft speeds maintain a fixed ratio relative to the crankshaft, but direct-drive marine propulsion plants synchronize propeller RPM directly with crankshaft RPM. Therefore, camshaft speed remains equal to the crankshaft and propeller speed of 135 RPM on a direct-drive two-stroke engine.