Question 61Motor Plants - Assistant Engineer

The correct answer is C) securing the fuel supply. The main propulsion diesel engine in a vessel is normally shutdown by securing the fuel supply to the engine. This is the primary method for shutting down a diesel engine, as cutting off the fuel source will stop the combustion process and cause the engine to stop running. The other options, such as shutting off the air supply, overspeeding the engine, or securing the ignition system, are not the typical or recommended methods for safely shutting down a main propulsion diesel engine.