Ship engine control device and method

Detect the actual rotation number (Ne) of an engine (11) and feed back to the input side of a control unit (12). Input the actual rotation number (Ne) and a fuel index (FIe), which has been outputted from the control unit (12) to the engine (11), to an Rσ computation unit (13). Calculate a load resistance factor in the Rσ computation unit (13) from the actual rotation number (Ne) and the fuel index (FIe). Find the root mean square value (Rσ) of fluctuation components of the load resistance factor. Revise a target rotation number (No) downwards according to the root mean square value (Rσ).