The maritime industry relies heavily on model-scale testing performed in towing tanks for designing hulls and propellers. Alongside model testing, Computational Fluid Dynamics (CFD) has proven itself to be a valuable tool for complementing model-scale tests and gaining insight into flow features that are impossible or prohibitively expensive to measure. For smaller than ship scale simulations, the maturity of numerical tools arises from extensive Verification & Validation (V&V) exercises and the organization of several workshops. Currently, a significant advantage of CFD, namely its direct applicability to full-scale ships, is still not widely utilized due to the lack of experimental data available for validation exercises. Over the last decades, several initiatives have started to contribute to increasing confidence in full-scale CFD results. From the numerical side, workshops such as the one organised by Lloyd’s Register in 2016, Chalmers University in 2024 and the Wageningen Workshop in 2025 have focused on full-scale simulations, while the JoRes Joint Industry Project (JIP) has tackled the issue from the experimental data side, gathering full-scale data for six different vessels. The present work utilizes the results made available by JoRes JIP to perform a V&V exercise for resistance calculation of a full-scale vessel. The vessel in question is the Lucy Ashton, which was the focus of the previously mentioned workshop organised by Chalmers University. The present papers focus on investigating the effects of several numerical settings parameters on the modelling error for calculations performed at three Froude numbers. This work will investigate the effects of wall treatment, hull roughness and vessel attitude.