<p>One of the primary methods for studying ship maneuverability is the system-based prediction approach. For low-speed ships, maneuverability can generally be predicted using the three-degree-of-freedom (3DOF) model. However, for ships with significant roll motion during maneuvering, the four-degree-of-freedom (4DOF) model is required to accurately predict their behavior. Currently, there is limited research on the impact of including roll motion on the accuracy of these predictions. To compare the prediction accuracy of the 3DOF model and the 4DOF model that incorporates roll effects, this paper uses the KRISO Container Ship (KCS) as a case study, simulating both 3DOF and 4DOF turning and zig-zag maneuvers. The hydrodynamic derivatives used in these simulations were obtained through virtual captive model tests based on the Reynolds-Averaged Navier–Stokes (RANS) method in OpenFOAM, and the method was validated for grid independence. The simulation results from both the 3DOF and 4DOF models were compared with experimental data. The results demonstrate that the 4DOF maneuvering motion model for prediction is feasible and offers higher accuracy compared with the 3DOF model, thereby confirming that roll motion significantly affects the maneuverability prediction of the ship and cannot be ignored.</p>