Flettner rotor upgrade to improve wind-assisted propulsion efficiency

EcoNavis Solutions, a Glasgow-based developer, says it is working on a next-generation wind-assisted propulsion system aimed at improving the performance and commercial viability of Flettner-type rotor sails for deep-sea shipping.

The company’s “Eco Rotor Sail” keeps the conventional rotating cylinder design but adds a fixed aerodynamic appendage positioned downstream. EcoNavis says the device reshapes airflow in the rotor’s wake, with the goal of increasing thrust, reducing power demand and widening the range of wind angles in which rotor sails can operate effectively.

According to the company, initial simulations indicate a thrust increase of up to 10% alongside a 5% reduction in torque. CEO and founder Dr Batuhan Aktas said the concept addresses a key limitation of existing rotor sails, which tend to perform best in a narrower band of wind angles, and could improve consistency for operators over a typical trading year.

The development is backed by a GBP 100,000 research grant from Scottish Enterprise as part of a GBP 265,000 project. EcoNavis said the next phase will involve physical testing, including wind tunnel trials of a scale model at Politecnico di Milano in Italy. Subject to successful validation, the company said a full-scale prototype could be built this year for shipboard trials within an integrated power system.