Evaluation of Fuel Consumption for Ships in Actual Seas

Amendment of MARPOL Annex VI was adopted at International Maritime Organization at 2011 and it enters into force from January of 2013. Requested are the measures for the reduction of greenhouse gas emission from ships. For that purpose estimation of the fuel consumption of the engine in ship operating condition with accuracy becomes important. In operation ships encounter winds and waves. As for the engine, the operating conditions are changing by the disturbances in actual seas. In this paper a calculation method of ship fuel consumption is proposed considering the engine operation modes. The considered modes are the revolution constant or the power constant. The calculation treats the limits of the engine operation. The limits are the torque, the over loading protection and the fuel index of the engine. If the engine operating point is over the limits, the engine controls the revolution to decrease. At the same time the ship speed decreases and the fuel consumption per hour also decreases. The relation between ship speed and fuel consumption is discussed here.