<p>This study explores the impact of weather-driven variations on the optimum trim of a refrigerated cargo carrier during a single ocean-crossing voyage. Analysis of operational data from onboard monitoring systems shows that trim adjustments, responsive to real-time weather conditions, can yield significant fuel savings, with potential reductions of up to 4.6% in fuel consumption per distance travelled. Compared to model test results obtained in calm conditions, the findings highlight the impact of varying weather on the vessel’s performance and underscore the operational importance of adaptive trim adjustments. This research aims to fill a critical gap in the existing literature by examining trim optimization under real weather conditions. Limitations include the focus on a single vessel and voyage. However, this study provides an essential starting point for future investigations across different vessel types and voyage conditions to enhance energy efficiency in maritime operations.</p>