Prediction strategy and full-scale validation of ship main engine energy consumption considering the influence of ocean currents

Accurate prediction of ship main engine power and fuel consumption during voyages is fundamental for ship energy efficiency management and optimization. Ocean currents, a critical environmental factor affecting ship navigation performance, have been inadequately addressed in existing studies on ship main engine energy consumption prediction. This paper proposes a novel strategy for predicting ship main engine energy consumption that explicitly accounts for ocean current influence. By conducting full-scale sea trials, the influence of currents on energy consumption is analyzed through their dual influence on navigation resistance and propeller propulsion efficiency. The methodology employs computational fluid dynamics (CFD), empirical formulas from the International Towing Tank Conference (ITTC), and the semi-empirical numerical navigation model (SNNM) to calculate calm-water resistance, air and wind resistance, and wave-added resistance, respectively. Additional resistance induced by currents is quantified based on discrepancies between ship's speed through water (STW) and speed over ground (SOG). Subsequently, main engine power and fuel consumption are determined by integrating propeller propulsion efficiency and power transmission losses within the propulsion system, with particular attention to current-induced variations in propeller advance speed. To validate the strategy, full-scale sea trials were conducted with the training ship Yukun in the Qingdao-Dalian coastal area of China under stable engine power conditions, supplemented by open-source regional marine environmental data. Comparative analyses demonstrate that the proposed strategy—considering both current-induced resistance and propeller efficiency modifications—significantly reduces prediction errors compared to approaches neglecting currents or addressing only partial current effects. These results underscore the critical importance of incorporating current-driven resistance and propulsion efficiency changes for accurate main engine energy consumption prediction.