Hydrokinetic energy recovery using a controllable-pitch propeller on a kite-assisted ship: Propeller performance mapping and a notional route case study

To enhance the efficiency of wind-assisted ships, the propeller may operate as a turbine. Because harvesting efficiency is strongly dependent on blade pitch, this study maps the propulsive and generative performance of a controllable pitch propeller (CPP) by simulating the Potsdam Propeller Test Case (PPTC) across a wide range of blade and advance angles. The power coefficient ( C P ) reaches 0.22 at design pitch, but achieves a global maximum of 0.44 at a 215° reversed pitch. The VORTEX ship performance model utilised this map to evaluate a notional merchant vessel with a 160 m 2 kite on a transatlantic route. Only mechanical shaft energy was considered, electrical losses are neglected. Results indicate hydrokinetic energy harvesting delivers minimal benefits over wind-assist alone at transit speeds of 18 kts and above. However, effectiveness scales rapidly during slow-steaming; at 15 kts , harvesting provides a 7.3% relative improvement over kite-assist alone (raising the absolute voyage energy reduction from 9.3% to 10.0%). System performance is sensitive to wind conditions, ship speed, kite size, and propeller type; notably, fixed-pitch propellers recover three to eight times less energy than CPPs. While maximising energy recovery requires CPPs capable of full blade inversion, conventional CPPs still capture the majority of the available generative benefit.