Equivalence of Power Reduction and Fuel Savings in Wind-Assisted Ships
Jonas Thiaucourt, Xavier Tauzia, Simon Le Guen, Maëlle GiraudAbstract
This paper investigates the relationship between propulsion power reduction and fuel savings in wind-assisted ships, focusing on hybrid machinery configurations where propulsion and electrical power generation are coupled. A modelling framework is developed to quantify these interactions for a Very Large Crude Carrier (VLCC) equipped with a controllable pitch propeller and a shaft generator operating in Power Take-Off (PTO) mode. Simulations are performed under moderate wind-assistance conditions, equivalent to 5% of the required propulsive force, and three machinery control strategies are compared: maximizing propeller efficiency, minimizing main engine specific fuel oil consumption (SFOC), and minimizing total fuel consumption across both the main and auxiliary engines. Results show that while fuel savings generally scale with the wind-assisted thrust contribution, deviations of up to 1.4% occur depending on the control strategy: the best-performing strategy improves fuel savings from −5.7% to −7.0%, corresponding to a 23% relative increase, without requiring any hardware modifications. These findings highlight that accurate performance assessments of Wind-Assisted Propulsion Systems (WAPS) must explicitly consider machinery operating points to avoid under- or overestimating fuel savings, and demonstrate that operational optimisation can unlock additional efficiency gains in hybrid ship architectures.
Keywords
wind-assisted propulsion systems; hybrid machinery; controllable pitch propeller; shaft generator; ship energy efficiency; marine propulsion