An assessment is made of the hydrodynamic interaction forces acting on a tug sailing freely in the vicinity of the bow of a large container vessel. For this purpose, a series of towing tank test have been performed during which the model of an azimuth stern drive tug was towed together with the model of a container carrier. Forces and moments on the tug model were measured for a range of relative positions and drift angles at multiple forward speeds. The model test results were incorporated in a fast-time simulation program to assess the steering action required to keep the tug at a fixed station by controlling the thrust and azimuth angle of both thrusters. Through simulations at different positions at which the towline is passed, an assessment is made of the most suitable position to perform this action.