Abstract
There exist two outstanding streams of researches on the optimization of ship routing operation : the optimum solution of ship speed distribution under the weather and the optimum steering control to reduce the propulsive resistance. Up to now, they have been studied separately each other.
In this paper, the fuel saving criterion for the navigating ship is formulated precisely on the basis of the propulsive motion equation under the weather condition. It consists of some vital ship operation variables such as displacement, ship speed (main engine output), course deviation, rudder angle and many physical characteristics data determined definately for a given ship.
Although it is rather complicated with lots of ship's paramaters and main engine performance data, it is proven that this totalized criterion can be hierarchically decomposed to two performance indices by applying the optimum control theory and the non-dimensionalization technique for the ship maneuverability parameters. As a result of this hierarchical decomposition, the ship speed distribution under the weather can be evaluated with the value of performance index for the optimized steering control in use.
This feature ensures the real optimization of the ship routing operation, justifies approximately the seperate approach of the above two streams and suggests the possibility of integration of optimum ship operation control technique.
