Seasonal Performance of a Sail-Assisted Parallel Hybrid Marine Vessel with Power-Follower Control

This study evaluates seasonal fuel use and power sharing in a sail-assisted parallel hybrid vessel. A state-of-charge (SOC)-adaptive power-take-off/power-take-in power follower is implemented in MATLAB/Simulink for the Kuala Terengganu–Singapore–Langkawi return route. Case A uses diesel propulsion. Case B adds a shaft motor–generator, a 430.08 kWh battery and 32 m2 of photovoltaic (PV) area (6.72 kWp). Case C combines the same hybrid machinery with 312 m2 of sails and 182.4 m2 of PV (38.304 kWp). Forty-eight 27-day simulations cover January, April, July and October of 2022–2025, with four matched year-periods per month. Fuel consumption follows A > B > C in every period. Overall propulsion fuel decreases by 0.85% in B and 3.89% in C relative to A. The additional C-to-B saving is 4.17 ± 0.64% (mean ± SD) in January. This difference includes both increased PV capacity and sail assistance. Motor and generator modes remain mutually exclusive, with SOC within 30.01–100%. Higher January waves increase propulsion demand, while stronger winds increase sail assistance. January engine energy decreases from 42.40 to 40.24 MWh per cycle despite a decrease in engine efficiency. The results show how seasonal demand and renewable inputs affect the evaluated configurations. They remain conditional on the estimated component maps, wave-resistance extrapolation and irradiance-based PV representation.