1軸CPP装備船の減速時の操縦性能

Abstract

When a ship proceeds to a harbour, the captain may order "stop engine". In case of the fixed pitch propeller (FPP), the propeller is usually idling according to the ship's forward speed, and this propeller idling can still keep the rudder effectiveness. While the controllable pitch propeller (CPP) is equipped, the propeller blade angle is turned to 0°instead of the engine stop, and brakes ship's speed. This 0°of CPP blade angle, however, may shut the inflow stream of rudder, which introduces a significant reduction in manoeuvrability. In this paper, hydrodynamic forces acting on hull and rudder are investigated. And the following characteristics are pointed out in regard to the forces (1) decreasing the rudder force significantly. (2) producing an additional yaw moment induced by the rotation of CPP with 0°of blade angle. Several coasting manoeuvres are simulated based on the hydrodynamic forces. Then they are confirmed by the free-running model tests. In order to improve the reduction in manoeuvrability during these coasting manoeuvres with 0°of CPP, a new control sequence of CPP is proposed here. This idea has been applied to the full-scale ship "Shinyo-maru". From the tests, it is proved that the new CPP controller well improves the coasting manoeuvrability of the CPP equipped ship.