The role of tug boats is significant when assisting ships with limited manoeuvring capabilities. Hence, knowledge of the hydrodynamic interaction effects that act on a tug under these operations is of great practical value for the tug master in order to avoid damage, collision, or capsizing. Computational Fluid Dynamic (CFD) simulations are increasingly being adopted as a tool of analysis for determining the interaction effects in such vessel manoeuvres. However, one of the major challenges faced in CFD, is that the results can vary greatly depending on the numerical model settings. This paper investigates modelling techniques and the accuracy of CFD generated interaction forces and moments acting on a tug hull operating at different drift angles, and at lateral and longitudinal locations along a tanker hull against Experimental Fluid Dynamics (EFD) data.