Bremen, Germany  - German companies said Thursday they are to order four new high-technology ships which will be able to lower stilts 50 metres to the seabed and jack themselves up.

Cranes on the vessels may need only about a week to assemble an offshore wind turbine, according to details from civil-engineering company Hochtief in Bremen. The windmills will be built on concrete artificial islands.

The new fleet, operated jointly with the Beluga shipping company of Bremen, would be able to erect 160 wind turbines a year.

Hochtief already operates such a ship, the 4-year-old Odin, which has been contracted to put in place a 45-metre high foundation for a transformer in the middle of the Alpha Ventus wind farm in German coastal waters of the North Sea.

A Beluga spokeswoman said a contract would be signed next week to spend 800 million euros (1.07 billion dollars) on the new-technology ships, with all four to be in operation by 2012.

Each will have four stilts and will take all the components out to the watery building sites and accommodate all the workers.

Beluga chief executive Niels Stolberg told the newspaper Weser Kurier that no competitor in the world would offer as much. A Hochtief executive, Martin Rahtge, said there were currently fewer than 10 ships in the world with this capability.

Faced with complaints that wind turbines spoil scenery on land, Germany has licensed 21 wind farms offshore, but the engineering problems of building the masts in up to
40 metres of water have held the business back.

Hochtief dumps crushed rock on the seabed, then assembles hollow towers of prefabricated concrete as a base. Above the water line, the wind-turbine masts are bolted to the concrete. The cranes then place the rotors and generators on top.(dpa)