Magnus effect

Norsepower Rotor Sails are modernized version of Flettner Rotors. The Rotor Sail technology is based on the magnus effect. When wind meets the spinning Rotor Sail, the air flow accelerates on one side of the Rotor Sail and decelerates on the opposite side of the Rotor Sail.

The change in the speed of air flow results in a pressure difference, which creates a lift force that is perpendicular to the wind flow direction. The same principle applies to all rotating spheres and cylinders. This can also be observed for example in golf, tennis or football, where spinning balls curve in flight.

Norsepower Rotor Sail

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 Solution is around ten times more efficient than a conventional sail, because more lift is produced with a much smaller sail area. Due to its simplicity, it requires no reefing or crew attention when in operation. It is "push button wind propulsion" from the bridge.

This allows the main engines to be throttled back, saving fuel and emissions while

providing the power needed to maintain speed and voyage time.

The technology, the basic concept of which is known as a Flettner Rotor, was originally invented by Finnish engineer Sigurd Savonius and was later demonstrated by Anton Flettner in an Atlantic crossing that took place in 1926.

The original basic engineering solution has a limited degree of sophistication, but Norsepower has created various new improvements for which several patents have been granted.

The optimal number and size of Norsepower Rotor Sails are based on the size, speed, and operating profile of the target vessel. 

Norsepower Rotor Sails are available in three sizes with Rotor Sail heights of 18, 24, or 30 metres. The essential parts of the Rotor Sail Solution are:

  • Norsepower Rotor Sails, which deliver the forward thrust

  • A control panel, which gives the captain full control of the operation and performance of the Norsepower Rotor Sail Solution

  • A fully automatic control system, which optimises the forward thrust of the Rotor Sails

  • A low-voltage electrical power supply to each Rotor Sail.


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Tel. +358 40 671 4977 | Tammasaarenlaituri 3, FI-00180 Helsinki |

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