Cooling load is an important component of ship energy consumption. The ship’s envelope constructed from aluminium alloy possesses a very low thermal storage capacity. This results in the temperature of ship cabin being significantly influenced by changeable solar energy reception angles and dynamic thermal transfer boundary conditions, necessitating a higher cooling load to maintain a comfortable cabin temperature. At present, research on reducing cooling load primarily focuses on active energy-saving technologies, exemplified by enhancements in air conditioning system performance. However, there is limited research on reducing cooling load through passive energy-saving methods. Therefore, a dynamic energy-saving strategy that incorporates phase change materials (PCMs) into the ship’s hull is firstly proposed. In this study, the dynamic energy-saving strategies utilizing PCM panels are investigated through both mooring and sailing experiments. The PCM melting time, dimensionless temperature rise (DTR), thermal insulation performance (TIP), heat exchange rate (HER), comfort temperature rate (CTR) and air conditioning load (ACL) have been analyzed to evaluate the thermal performance of the ship cabin. It can be observed that ships equipped with PCMs have increased thermal storage capacity, increased temperature comfort zones and decreased air conditioning loads, especially under complex sailing conditions. The experimental results indicate: (1) The total energy storage is 43.72kW•h per hour, with a heat exchange with the cabin environment of 14.76kW•h; (2) PCM panels installed at the bottom of the ship offer longer insulation duration; (3) Under sailing conditions, the DTR is 15.19%, the TIP is 12.27%, and the HER is 60.45%. Compared to mooring conditions, these indicators have increased by 36.23%, 24.29%, and 71.32%, respectively, suggesting that PCM panels have shown superior performance during sailing.