The ship manoeuvring simulators of Flanders Hydraulics Research (FHR) are used as a policy-supporting instrument (study and advice) and as a training installation for nautical experts. Both applications require realistic simulation models. Such manoeuvring models are developed by the FHR and describe the hull, propeller and rudder forces at various under keel clearances in a horizontally unrestricted environment. The manoeuvring models are derived from a large set of scale model tests carried out in the towing tank for manoeuvres in confined water at Antwerp. The towing tank tests and the resulting manoeuvring models make abstraction of external factors such as current and wind, so that these effects are not directly contained in the manoeuvring models but are added via specific modelling. For example, the influence of current is taken into account by evaluating the hydrodynamic hull forces at relative speed components defined as the difference between the ship speed and the current speed. Wind effects are modelled on the basis of external forces corresponding to the aerodynamic force components on the ship's superstructure. Both for the calculation of wind forces on ships and for the influence of current components on the manoeuvring behaviour, FHR wishes to evaluate the current modelling in the simulators and optimise it where necessary.