Ferry operator Scandlines signed an agreement with Norsepower Oy Ltd, leading clean technology and engineering company pioneering modern wind propulsion technology, to install Norsepower’s Rotor Sail Solution on board the M/V Copenhagen, a hybrid passenger ferry.





Illustration of Scandlines hybrid ferry M/V Copenhagen with Rotor Sail.

Operating between Rostock in Germany and Gedser in Denmark, the M/V Copenhagen belongs to the world’s largest fleet of hybrid ferries, which combines diesel and battery power. Since 2013, Scandlines has invested more than €300 million in building and retrofitting ferries from conventional diesel-driven to hybrid ferries. With the addition of Norsepower’s technology, the vessel will further reduce its emissions.

The Norsepower Rotor Sail Solution is a modernized version of the Flettner rotor (earlier post)—a spinning cylinder that uses the Magnus effect—a commonly observed effect in which a spinning ball or cylinder in this case curves away from its principal path to harness wind power to thrust a ship.

The Magnus effect observes that a revolving body moving relatively to a surrounding fluid—in this case, air—is subjected not only to drag, but also to lift. As the speed of the cylinder—spinning at right angles to the flow—increases, the pressure decreases on the side of the cylinder where the natural flow and the spin-induce flow combine. The decrease in pressure generates lift, and the lift increases as the surface velocity increases (per Bernoulli’s theorem).

The thrust induced by the Magnus effect can be utilized in ship propulsion by placing a cylinder on the open deck of the vessel and by rotating it around its vertical axis. A variable electric drive system, which is powered by the ship's low voltage network, is used for rotation of the Rotor Sail.

The Norsepower Rotor Sail is the first data-verified and commercially operational auxiliary wind propulsion technology for the global maritime industry. When wind conditions are favorable, it enables the electric propulsion thrusters and center propel to be throttled back, reducing emissions, while providing the power needed to maintain speed and voyage time. Because it generates supplementary thrust from wind, the solution is compatible with all other emissions saving technologies.

The route between Gedser to the north and Rostock to the south is almost perpendicular to the prevailing wind from west giving Scandlines favorable conditions for using Rotor Sails on the ferry crossing.

Preparations for the retrofit will take place in November 2019 with the installation scheduled for Q2 2020. M/V Copenhagen is set to be retrofitted with one large-sized Norsepower Rotor Sail unit that is 30m in height and 5m in diameter.