Low Speed Ship Manoeuvrability: Mathematical Model and its Simulation

Abstract

In case of offshore support vessels, it is quite important for their behaviours in low speed manoeuvrability. It is not easy to operate offshore support vessels and it raises an importance to train crew by a ship handling simulator. Therefore it is quite hot issue for ship handling simulator vendors to provide mathematical model of support vessels, but from the users’ point-of-view the model used for the simulator is not clear. Up to now some mathematical models are proposed in the literature, but the validation is not yet done carefully. For example, cross flow model is the main part for hydrodynamic force in low speed ship manoeuvring. From model ship experiments of various types of ships and from some comparison study, it is found that further discussion is necessary. In this paper, sway force and yaw moment as well as surge force will be treated in low speed condition with certain sway and yaw motions. There are many experiment results for such hydrodynamic forces and moment, especially for sway force and yaw moment, for sway motion, but those for yaw motion is quite limited. In this paper, such hydrodynamic forces and moment for both sway and yaw motions are calculated and validated with experiment results. Some manoeuvring simulation will also demonstrate which terms and/or expressions in the mathematical model are affecting the motion.