Abstract: Objectives In modern marine technology, hydrodynamic performance is critical for ship maneuverability. Numerical simulation offers a cost-effective alternative to experimental methods by overcoming their financial and operational constraints. Methods This study employs the OpenFOAM-based naoe-FOAM-SJTU solver integrated with the Shear Stress Transport k-ω turbulence model and an overset grid approach to simulate hydrodynamic forces during the sway motion of a KVLCC1 hull under deep and shallow water conditions with varying depth-to-draft ratios. Results Validation against experimental data shows maximum deviations of less than 5% in sway force amplitude, yaw moment amplitude, and phase angles, confirming the reliability of the overset grid method for hydrodynamic predictions. Conclusions Comparative flow field analyses demonstrate pronounced shallow-water effects manifested through modified near-hull velocity profiles and wake vortex reconfiguration. Notably, free-surface wave generation shows negligible post-stabilization variations across depth conditions, indicating limited steady-state hydrodynamic influence. The results enhance mechanistic understanding of vessel-hydrodynamic interactions in confined flows, offering actionable strategies for marine system optimization.