Focussing on the sea-going maneuverability of a 105-passenger hovercraft, the authors made investigations through series of model tests and computer simulations. The wind forces acting on a scale model, which represents superstructure and cushion form, were measured in a wind tunnel test. Oblique towing tests with self-lifting model were carried out for the hydrodynamic characteristics between cushion skirt and water plane. Regarding the characteristics of control surfaces, the force measurement tests with ducted propeller and rudder in wind tunnel were carried out. Based on these results of model tests, the authors developed a simulation program which employs proper mathematical models for each force components, namely cushion skirt, wind, propellers, rudders and thruster. The output of simulation showed fairly good agreement with the results of actual sea trial. Especially in the case of course keeping in beam wind, the reverse of check-helm direction around Froude number of 1.0 experienced in actual operations were confirmed through computer simulation. Lastly the results of extensive investigations on the sea-going maneuverability of the hovercraft are explained.