Mathematical model for automatic berthing simulation of a twin-screw ship

Abstract

Compared to the ship’s manoeuvres with medium and high forward speeds in the open sea, the ship’s forward speed becomes very low in the harbor, the drift angle increases up to about 90 degree or more, in particular, during berthing motions. More attentions should be needed in the simulations of harbor manoeuvres. In this study, 3-DoF mathematical models are established based on the captive model tests of a twin-screw ship, which was designed as an initial hull form of Korea Autonomous Surface Ship (KASS). In order to consider the hull forces and moments during berthing motions accurately, large angle static drift, yaw rotating, and astern resistance tests are carried out, and the hydrodynamic characteristics are considered in the hull model. Propeller model is modified so that the open water characteristics at 4 quadrants are included. After thruster models are added, the berthing motions are simulated, the proposed models are verified by using the free-run model test results.