ETI to launch project to develop Flettner rotor sails for ships; seeking at least 10% improvement in fuel efficiency

Via GCC: http://www.greencarcongress.com/2016/03/20160319-flettner.html

The Flettner Rotor Supply, Install and Commission Project will deliver a full scale demonstrator of Flettner Rotor technology on a large ocean going vessel which the ETI intends to source for the demonstration phase. Flettner rotors use a spinning cylinder to convert the force of the wind into thrust that helps propel the ship. . . .

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There's some nice video from the '20s.

The Cousteau Society built a ship using a somewhat similar idea back in the '90s, but AFAIK no one else has taken up the idea, so I assume there are practical problems: https://en.wikipedia.org/wiki/Turbosail

Very interesting. Since the force is perpendicular to the wind direction, it seems such a device would only provide improvements with a crossswind: a tailwind or a headwind would not be useful.

A comment in that article included a link to a sail which could *also* be added and deployed for trips with a tailwind: SkySails.

RegGuheert said:

Very interesting. Since the force is perpendicular to the wind direction, it seems such a device would only provide improvements with a crossswind: a tailwind or a headwind would not be useful.

A comment in that article included a link to a sail which could *also* be added and deployed for trips with a tailwind: SkySails.

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Apparently Flettner's design allowed sailing much closer to the wind than a normal sail: 20-30 degress vs. ~45 deg. See https://en.wikipedia.org/wiki/Rotor_ship

Under "Voyages". That article also says that the ship couldn't compete economically against diesels at the time. I suspect little has changed in the interim, although the article does mention some more recent attempts. There's also an excellent article (from 1936) cited in the wiki article, which goes into far more detail on the design and performance of the Buckau and the Barbara: http://www.shippingwondersoftheworld.com/rotor-ships.html