The use of mathematical models and associated computer simulation is a well established technique for predicting the behaviour of large marine vessels. For a variety of raisons, mainly related to effects of scale, existing models are unable to ad equately predict the manoeuvring character istics of smaller vessels. The accuracy with which the performance of a boat under autopilot control can be predicted also leaves much to be desired. The paper presents a mathematical model to simulate small boat behaviour and so can assist with the design and testing of boat autopilots.
The boat model is presented in six degrees- of-freedom, which, with suitable wave disturbance terms, allows motions such as broaching to be analysed. Instabilities in the performance of an autopilot arising from such sea-induced yaw motions can be assessed with a view to improving the control algorithms and methodology.
The research rectifies the glaring omission of a small boat mathematical model, the framework of which could be expanded to encompass other marine vehicles. Initial results are promising and show good agreement with real data.
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