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February 01, 2007

Kite-flying cargo ships?

Mausi's been watching a fascinating programme on TV last night. You think the days of sailing ships as commercial transport vessels are over? Wait until you see the invention of two German engineers: cargo ships are pulled through the ocean by big kites called "Skysails"!

The skysail has the form of a paraglider and will be huge - up to three quarters of a soccer field. It is made from new high-tech and ultra light materials and has a little gondola attached to it that contains sensors for measuring wind direction and velocity. Data are transmitted to the autopilot who adjusts the direction and velocity of the ships so that the pulling force of the kite is always at its maximum. The kite is flown in curves in a height of up to 500 metres.

The kite is connected to the ship by a single rope that only branches out farther up. If the kite were operated by two ropes instead of one this would result in the cargo ship leaning to one side as a sailing ship does which would most probably cause the load to slide as well. In heights between 300 to 500 metres winds and breezes are stronger and more reliable than closely to the sea surface so that the kite will always get enough wind to make it tow the ship effectively. Interestingly all the major routes the merchant sailing ships travelled came into existence because those ships could not cross before the wind. And 80% of these routes with their major trading ports still exist. So quite a number of our modern cargo ships should be able to use skysails effectively.

The kite could not tow a cargo ship of up to 100,000 tons all by itself of course. But it could save a considerable amount of fuel, probably up to 50%. In 2004 the biggest container ship was the Hongkong Express who needed 50,000 litres for 100 km (I don't know if that is true but my pocket calculator says that's 9 metres to the gallon). Saving up even 20% of fuel in times like this would be a considerable amount of money saved. Not talking about the cubic metres of carbon and sulphur dioxides the atmosphere will be spared as well.

When will we spot the first skysails? Probably as early as this year. After testing a model (an exact replica of a container ship on the scale of 1:26) on the Baltic sea near Wismar where the waves matched the size of the model the TV programme showed a real cargo ship being towed by a skysail of 80 square metres. It looked great. And with all this modern weather forecasts, GPS and other fancy computer data it should be possible to pull down the kite in time even from several hundred metres height if a storm is coming up.

If you are interested to see the real thing - google Skysails website. There's an English version for you to enjoy.

Posted by Mausi at February 1, 2007 09:04 PM

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