The rapidly growing demand for more information on the manœuvrability of ships is distinctly recognizable nowadays, especially by an industrial service institute in the field of ships’ hydrodynamics like the Netherlands Ship Model Basin. At this moment, means like manœuvring basins, rotating arms and towing banks with planar motion systems are available at many places. The information obtained from ship-model tests in such facilities is still insufficient to satisfy all questions. There is a growing interest in training people under the circumstances which will confront them on ships in the near future. Governments, harbour authorities and shipowners like to know the criteria by which a decision to enter a harbour with a large ship can be taken. The human aspects of manœuvring very large ships have raised an interest in designing semi-automatic pilots. A clear explanation of the role of the human operator was presented by Segel at the ‘First Symposium on Ship Manoeuvrability’ in Washington in 1960. That paper discusses the many items that influence the path of the ship, which the pilot, captain or helmsman desires to follow. The block diagram presented in Fig. 1 illustrates the complexity of the phenomenon.