Things To Know In Main Engine System Of A Ship. A ship's main engine system is the core propulsion system, typically a large diesel engine, that drives the ship's propeller and moves it through the water. It encompasses various subsystems responsible for fuel delivery, combustion, power generation, and control. The main engine converts the chemical energy of fuel into mechanical energy, which is then transferred to the propeller via a crankshaft and potentially a gearbox or electric motor. ■ If