What is a "cold start" in marine diesel engines?

A "cold start" in marine diesel engines refers specifically to the act of starting the engine without pre-heating. Diesel engines require a certain temperature for optimal combustion, and pre-heating is crucial in ensuring that fuel ignites properly when the engine is cold. When an engine has been inactive for a period, its components can cool down significantly. Pre-heating helps to raise the temperature of the fuel and engine components, leading to more efficient combustion and reducing wear on the engine parts during startup.

In contrast, starting the engine with insufficient fuel or starting it on low battery may lead to operational difficulties but does not specifically define a "cold start." Similarly, starting the engine after a long period of inactivity might indicate that the engine is "cold," but without pre-heating, it does not encapsulate the full implications of starting without the necessary heat to facilitate proper operation. Thus, the most accurate definition of a cold start among the options provided is the lack of pre-heating before engine initiation.