Ocean voyages could double the fuel savings for ships using wind-assisted propulsion compared with test results from shortsea routes, according to research into voyage optimisation with Flettner rotors.

Rotor Sails could deliver fuel savings of up to 20% on deepsea routes, compared with about 10% recorded so far in the North and Baltic seas, according to studies by Dutch company C-Job Naval Architects using voyage optimisation and weather routing software developed by Finland’s NAPA.