Rotor Sail Delivers Savings on Viking Grace, Tests Confirm

Norsepower’s Rotor Sail auxiliary wind propulsion technology has great potential to deliver savings on the Viking Line-owned and operated passenger ship Viking Grace, independent test results showed.

As informed, long-term LNG marine fuel savings are expected to be up to around 300 tons on an annual basis.

When looking at fuel consumption alone over the measurement period, the savings were not immediately evident. However, when expert analysis companies NAPA and ABB reviewed the data, they were able to isolate an evident change in the propulsion power breakdown of Viking Grace, caused by the Rotor Sail, according to Norsepower.

The same conclusion was confirmed with a strain gauge analysis, where forward thrust of the Rotor Sail was measured and converted into propulsion power.

Based on the different analyses, the expected long-term change in Viking Grace’s annual fuel consumption due to the auxiliary wind propulsion system has been verified to be between 231 and 315 tons on annual basis, equalling an average propulsion power between 207kW and 282kW.

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According to the analysis results, the technology delivers more forward thrust on the open sea legs of the route for the Viking Grace, but due to the route being located mostly in the archipelago, the annual fuel savings potential is on the same level within both route areas.

As a result, Viking Line and Norsepower have agreed to continue using and optimizing the Rotor Sail on Viking Grace with the technology now fully operational.

“When the test period began, we had some challenges with our new product, but were able to fix them quickly, and since the end of September 2018, the technical availability of the Rotor Sail has been around 97%,” Tuomas Riski, CEO, Norsepower, commented.

“This project has confirmed, that our technology works also with high-speed cruise ferries and that favourable results can be achieved with a service speed of 21 knots,” he added.

Riski further said that the Rotor Sail was used in extreme weather conditions including icing events and high wind speeds over the past year. Based on experiences, the company said the system can be operated around the year without any weather-related issues.

Commenting on the trials, Jan Hanses, CEO of Viking Line said:

“We want to pioneer the use of solutions that reduce the environmental load. Viking Line has been testing the Rotor Sail on M/S Viking Grace for a year now, and together with Norsepower we will continue testing and optimising the sail for its current route.” 

Back in April 2018, the 57,565 GT Viking Grace was retrofitted with one medium-sized Rotor Sail unit, making it the first-ever global LNG/wind electric propulsion ship.

The ship operates in the archipelago between Turku, Finland, and Stockholm, Sweden.

In addition to the installation onboard Viking Grace, Norsepower’s system is also installed onboard Maersk Tankers’ 110,000 dwt Maersk Pelican and Bore’s M/S Estraden, a 9,700 dwt RoRo carrier.

Earlier this year, ship classification society DNV GL issued a type approval design certificate for Norsepower’s Rotor Sail Solution. The approval was granted after a design assessment of Norsepower’s 30-meter by 5-meter rotor sail, two of which have been installed onboard Maersk Pelican.

Norsepower’s solution thus became the first auxiliary wind propulsion system on board a commercial ship to receive the certificate.