A vessel’s engine and propeller are optimized and designed for a given operational and max. speed. If the operational speed of the vessel is generally lower than the one originally optimized for, it may be beneficial to consider derating of the main engine and propeller. Derating as a retrofit product offers reduction of the total fuel consumption by improving the match between the operational speed and optimization speed. Derating is usually an attractive option for fuel oil savings if a reduction of 10-15% of the max. speed at SMCR can be accepted. A standard derating calculation made by MAN Diesel & Turbo takes into account the benefit gained from exchanging the original propeller with a new propeller having an optimized diameter designed for the required optimizing speed and reduced max. speed.

Engine type

All MC/ME engines above 50 bore