Unified Mathematical Model for Ocean and Harbour Manoeuvring

Mathematical models for ship manoeuvring have greatly progressed after IMO standard for ship manoeuvrability was settled. These models have been well developed based on experimental and theoretical approaches, particularly for the ocean-going navigation where the forward speed is high. However, for harbour manoeuvring, there are still few works because of the complicated modelling doe to the large drift angle and turning motions that are induced by low forward speed. In this paper, the authors developed the simple and unified mathematical model that can be available from ocean-going to berthing manoeuvre. The principle of the model is based on linear hydrodynamic force and cross-flow drag theory. Then, the model is applied to the captive model test results of several ship models. From the comparison between measured and calculated by the mathematical model, it is found that the presented model can be well used for the prediction of very wide range of manoeuvring motion. The merit of this model is that the conventional linear hull force derivatives can be applied, and that the coefficients regarding to cross-flow drag are minimized and easily predicted by the regression formulas proposed here. This model is expected to be used for real time simulators as well as the manoeuvring simulation in early design stage.