Definition(s)
Main Propulsion Engines
Main propulsion engines and turbines are defined as those which drive main propelling machinery directly or indirectly through mechanical shafting and which may also drive electrical generators to provide power for auxiliary services. Auxiliary engines and turbines are defined as those coupled to electrical generators which provide power for auxiliary services, for electrical main propulsion motors or a combination of both.
Source: Rules and Regulations for the Classification of Mobile Offshore Units, Part 5, Main and Auxiliary Machinery, June 2013, Lloyd’s Register, Global Standards