The object of the assignment is to improve the formulations of the ship-ship interaction forces in six degrees of freedom for real-time simulation applications. By ship-ship interaction forces is meant the part of the hydrodynamic force which is solely due to the interaction phenomena, since superposition of hydrodynamic and external forces is the presumption in the ship-manoeuvring simulators of FHR. Existing formulations can be used as a starting point, but new innovative prediction methods are not excluded.