Norsepower — the developer of wind propulsion rotor sails installed on six vessels — offers lease financing, but its interest rates cannot compete with those that shipping company buyers can obtain.

Finance leasing was first mooted in 2019 to provide smaller shipowners with a way of renting the equipment on a service deal that would make their cost outlay more feasible.

But Norsepower chief executive Tuomas Riski said the Finnish firm was being asked for interest rates of 10%-plus, whereas clients — including Vale, Pan Ocean, Maersk Tankers, Shell Shipping & Maritime, Scandlines and Viking Line — could get loans at a few percentage points, at least before inflation started to bite.