The innovative Rotor Sail technology developed by the Finnish company Norsepower has been tested by Viking Line for three years. A Rotor Sail produces thrust based on phenomena called the Magnus-effect, and reduces the propeller power requirement. MS Viking Grace was the first passenger vessel fitted with a Rotor Sail. The test period of the Rotor Sail was completed in April. Viking Line wants to trial new environmentally friendly solutions on their ships also in the future. For example, the new MS Viking Glory has been built to be ready for installation of Rotor Sails. Norsepower's Rotor Sail solution is the first third-party verified and fully commercial mechanical sail. The fully automated control system senses when wind conditions are favourable and operate the Rotor Sails with no action required by the crew. In addition to Viking Grace, Norsepower's Rotor Sails have been installed on four ships, including Scandlines ferry M/V Copenhagen operating between Germany and Denmark and tanker Maersk Pelican. The next Rotor Sail installation project is starting soon.