This summer, in the North Sea can be seen the strange ship "E-Ship 1". On its upper deck are stuck up four high round cylinders, but they never sweep. These are the so-called Flettner rotors, changing the traditional sails.

Magnus efect

Anton Flettner (1885-1961) was a German aviation engineer and inventor. He made important contributions to airplane and helicopter design as well as to the maritime history as the man tried to change the sails. He had to travel long sailing the Atlantic and Indian oceans. Contemporaneous sailing ships had a rich range of sails.

Their equipment was expensive, complicated, and from the aerodynamic point of view was not very effective. Permanent dangers were usual for seafarers, who had to manage sails 40-50 meters in height during the storm. During the travel for a young engineer appeared an idea to change a lot of hassle and trouble presenting sails into easier, but more efficient equipment, which the main engine would be a wind.

Thinking of it, he remembered his countryman physicist Heinrich Gustav Magnus (1802-1870) aerodynamic tests. They found that the wind flow rotating cylinder, depending on the direction of rotation is exposed to one or the other direction.

Everything is very simple

Anton Flettner immediately thought that the sails can be replaced by rotating cylinders which were built on-board. He launched the idea in 1923 in one lake near Berlin.

About a meter long boat inventor mounted cylinder, this was spun by a clock mechanism. This boat with such "sails" went perfectly easy even when light breeze was blowing. It turns out that where the cylinder surface is moving against the flow of air, the wind speed decreases but the pressure increases. In the other side of the cylinder everything is contrary - the wind speed increases and pressure decreases. This pressure difference on opposite sides of the cylinder is the driving force that causes the movement of the ship. This is the main principle of rotor machine that uses wind power to propel a ship. It was all very simple, but only Anton Flettner "did not pass through" although Magnus effect was known.

The invention has proved

Sailing ship captains made fun of A. Flettner cylinder, which he wanted to change the sails. Inventor managed to attract moneyed patrons.  Flettner constructed an experimental rotor vessel, and in October 1924 finished construction of a large two-rotor ship named Buckau. The vessel was a refitted schooner which carried two cylinders (or rotors) about 15 meters (50 ft) high, and 3 meters (10 ft) in diameter, driven by an electric propulsion system of 50 hp (37 kW) power. These cylinders were spun by 45 hp diesel generator.

The Buckau set out on her first voyage in February 1925, from Danzig to Scotland across the North Sea. The weather was awful, and many sailing ships did not dare to leave the port. In the North Sea, the Buckau had to fight the strong winds and big waves, but the schooner lurched to the side less than the other sailboats.

During this trip it was not longer to shout the deck crew, which they, depending on wind strength and direction, had to change sails. It was enough one navigator on duty, who, without leaving the wheelhouse, was able to manage the activities of the rotor. Previously threemasted schooner crew consist of at least 20 seafarers, processing it into the rotary vessel, it was enough to have 10 seafarers on board.

The invention of A. Flettner was proved, however the Buckau was destroyed in a Caribbean storm in 1931 after it had sailed the Atlantic.

The absence of understanding pilotage

The German Admiralty impressed with the Buckau’s success commissioned the Weser Shipyards in Bremen to build a new, larger rotor ship on a proven design. The Barbara was launched in 1926. It was planned to equip the ship, which was 90 meters length and 13 meters width with three rotors of 17 meters height.

The Barbara, as was planned for some time successfully transported fruit from Italy to Hamburg. Approximately 30-40 percent of the trip time ship was powered by wind. When the wind was blowing at 4-6 score, the Barbara developed 13 knots speed.

It was planned to test the rotor ship in longer voyages in the Atlantic Ocean. However, in 1933, the Barbara was again transformed into an ordinary motor ship. The old sea wolves did not try to understand the "cylinder" control art. Ship changed owners, names, worked in various parts of the world, until finally in 1978, sank in a storm.

Remembered Yves Cousteau

The beginning of rotor ships seems to have been reasonably successful, but they did not receive a better future, and for a long were forgotten. Why? Firstly, rotor ships’ "father" A. Flettner plunged into the development of helicopters and was not interested in ships. Secondly, despite all its advantages, rotor ships remained sailboats with specific handicaps; the most important was their dependency on the wind.

The interest in A. Flettner rotors against appeared in the 20th century 80s, when scientists began to suggest various measures to reduce global warming, pollution, and more rational use of energy. One of them was the first French explorer Jacques-Yves Cousteau (1910-1997) who remembered rotor ships. The Alcyone was a ship operated by the Cousteau Society. It was created as an expedition ship and to test the operation of a new kind of marine propulsion system, the turbosail. The Alcyone was equipped with two of these unusual sails, which are used to augment its diesel engines. Since the accidental sinking of the Calypso, the Alcyone has been the Cousteau Society's expedition vessel. In 1985 it started voyages and sailed to Canada and the USA, sailed across Cape Horn, Australia and Indonesia, Madagascar and South Africa. The ship was relocated in the Caspian Sea where was sailing about three months and made some research. Presently the Alcyone is sailing with two different propulsions - two diesel engines and two turbosail.

Do the wind engines return?

The hull of E-Ship 1 was built by German shipbuilder Lindenau Werft in Kiel. The ship's launch took place on August 2, 2008, with the delivery date estimated for the first half of 2009. Steel construction work was completed in 2010, and the ship was docked at the North Sea.  The ship's bridge is located at the bow, and has three decks and two port-related long-boom cranes with payload capabilities of 80 and 120 tonnes. The ship has a rear ramp, and can function as a RoLo cargo ship. There are 15 members of crew on this ship.

In Singapore based shipping company in the industry "Wind Again", creating fuel and emission reduction technologies, offers a special structure (folding) Flettner rotor equipped tankers and cargo ships. They would reduce fuel consumption by 30-40 percent and pay off within 3-5 years.

In Finland operates marine engineering company Wartsila has plans to adapt turbosail in cruise ferries. This is related to Finnish ferry operator Viking Line which is committed to reduce fuel consumption and environmental pollution.

Adaptability of Flettner rotor to pleasure boats is exploring the German University of Flensburg. It seems that rising oil prices and concerns about global warming create favorable conditions for wind engines to come back.