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Viking Grace LNG ferry to install rotor sail; first LNG/wind electric propulsion hybrid ship

Norsepower Oy Ltd., a provider of low- maintenance, software-operated, and data-verified auxiliary wind propulsion systems, signed an agreement with Finnish shipping company Viking Line to install its Rotor Sail Solution onboard the M/S Viking Grace, an LNG-fueled cruise ferry.

The 57,565 GT M/S Viking Grace currently operates in the archipelago between Turku (Finland) and Stockholm (Sweden), and is already one of the most environmentally-friendly cruise ferries in the global maritime industry. With the addition of Norsepower’s technology, the vessel will further reduce its emissions, fuel burn and fuel costs; reducing carbon emissions by around 900 tonnes annually; equivalent to cutting 300 tonnes of LNG fuel per year.

Illustration of Viking Grace with one 24x4 Norsepower Rotor Sail
Illustration of Viking Grace with one 24x4 Norsepower Rotor Sail. Click to enlarge.

Preparations for the retrofit are underway, with the installation scheduled to take place during Q2 of 2018. Viking Grace is set to be retrofitted with one medium-sized Norsepower Rotor Sail unit that is 24m in height and 4m in diameter, making it the first LNG/wind electric propulsion hybrid ship.

The Norsepower Rotor Sail Solution, which can be installed on new vessels or retrofitted on existing ships without off-hire costs, is a modernized version of the Flettner rotor—a spinning cylinder that uses the Magnus effect to harness wind power to propel a ship. (Earlier post.)

The rotor sail operates on the principle called the Magnus effect. An electric drive system powered by the auxiliary grid in the vessel is used for rotation of the Rotor Sail. When wind meets the spinning rotor sail, the rotor sail accelerates air flow on one side and restricts the air flow on the opposite side. The resulting pressure difference creates a force that is perpendicular to the wind flow direction—a lift force. The circulatory flow, created here by the skin friction, is the same phenomena that creates lift for an aircraft wing. The same principle applies to rotating spheres and cylinders.

The Norsepower Rotor Sail is mainly designed for tankers, bulk carriers, ro-ro vessels and ferries, where the required installation space is available on deck; cranes and cargo handling equipment do not prevent installation; there is a high proportion of time-at-sea; and the prevailing wind conditions are favorable.

The solution is fully automated and senses whenever the wind is strong enough to deliver fuel savings, at which point the rotors start automatically—optimizing crew time and resource.

To date, independent data analysis indicates that up to 20% fuel savings per year can be achieved on routes with favorable wind flows, sufficient sized rotor sails, and appropriate service speed.

The technology has proven commercial applicability, with two small units of Norsepower’s Rotor Sails installed on board Bore’s M/S Estraden, a 9,700 DWT Ro-Ro carrier. Measured and independently verified by NAPA, the leading maritime data analysis, software and services provider, the Rotor Sail Solution delivered fuel consumption reductions of 6.1% for the Estraden.

This project has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement Nº 738282. Norsepower recently received €2.6 million from the European Commission and the Finnish Government’s funding agency for innovation, Tekes, to further its research and development program.



A lot of 'ifs' to reduce fuel consumption by 20%. The average will probably be below 10%.

Combining fuel engines exhaust with roto-sails + heat recovery could help?


I occasionally travel on this ferry.

I doubt that the power from this rotor can do more than perhaps cool a few drinks in the bar.

Account Deleted

Large ocean going vessels probably will not be returning to wind power. However, autonomous warships like the Sea Hunter might be a good candidate. Particularly, if they look like Victorien Erussard's Energy Observer (http://www.energy-observer.org/) which uses Wind, Solar, and Hydrogen.


Bio methane to DME with fuel cells can power large ships.
The rotor sail can help, but it requires energy itself. Try vertical wind turbines to generate rather than use electricity.

Bob Niland

When sailing into the wind, does this thing even compensate for its own aerodynamic drag?


Sailing into the wind is the same as with wings. High pressure on one side, low pressure on the other creates lift. You angle into the wind not directly at it.


One must assume that a few studies were done and scale models built before the full size one was attempted. I will give them benefit of the doubt until we have real case data. The data so far has stated (in the article) that 20% savings annually are expected, not 10%.

As Aha

just googled that ferry have 4 x 7330 kW generators and sails for 9 hours/day, maybe idle generation that makes 20% achievable...

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