Marine navigation is strongly influenced by oceanographic factors such as currents, rapidly changing sea conditions, and complex wave interactions. These elements affect both the structural integrity of a vessel and its overall operational safety, especially when navigating in harsh or unpredictable marine environments. Understanding how ships respond to different sea states is therefore essential for safe design and efficient operation.

This study investigates the impact of sea states on vessel motions and vertical bending moments, using a representative case study. Hydrodynamic analyses were performed through a panel-based numerical approach under stationary and advancing conditions, considering head and beam seas. Both frequency- and time-domain simulations were carried out, including the derivation of Response Amplitude Operators (RAOs) in regular waves and structural responses in irregular seas based on an empirical spectrum. The resulting hydrodynamic loads were applied to stress and fatigue assessments, and fatigue life predictions were made under extreme conditions. Comparisons with classification society rules provided further evaluation of structural performance.

The outcomes contribute to a better understanding of vessel response in complex wave environments, supporting design optimization and operational safety. The methodology also provides a foundation for integration with finite element modeling and machine learning for real-time structural health monitoring, with potential applicability across different ship types and scales.