A jack-up platform is a mobile platform in the water that can stand on the sea floor with the help of lowerable legs . In contrast to the installation ships, it does not have its own drive, but is pulled to new locations with the help of tugs .
With the legs raised, a jack-up platform is moved by tugs to the desired position, where the legs are then lowered. By absorbing ballast water and lifting the platform above the sea surface, pressure is exerted on the legs so that they are firmly anchored in the sea floor. This creates a platform that is firmly connected to the seabed.
Jack-up rigs can only be used in relatively shallow water, depending on the type, up to a maximum of 130 m water depth.
In port construction, jack-up rigs are used, in particular, for pile pile driving from the water (e.g. for quay walls ). While they serve as a working level for Piling and are mainly used in areas where, despite rough seas and high tides high Rammgenauigkeit is required.
Construction of offshore wind farms
The jack-up platform Odin was built in 2004 and converted in 2009 for use in the offshore sector. She received a 300-ton crane. After this conversion, Odin was involved in the construction of six of the twelve wind turbines for the first offshore wind farm in the German EEZ " alpha ventus ".
The jack-up platform Thor is the first jack-up platform that was specially designed for the installation of wind turbines. It was initially chartered out for the construction of the BARD Offshore 1 wind farm . Each leg is 82 meters long and weighs 530 tons. There is a plate over eight meters in diameter on each foot. When fully loaded, the Thor can weigh up to 10,000 tons. The jack-up platform should not sink deeper than two meters into the sediment . It takes three hours to gradually extend your legs.
In the field of the construction of offshore wind farms, installation vessels (jack-up platform with its own drive, stronger crane and more space for transporting components) are increasingly being used. Due to the frequent repositioning when setting up the individual wind turbines, a separate drive is an advantage. In addition, specially designed installation vessels are designed to transport several complete wind turbines (or parts thereof) from the loading port to the wind farm project areas.
- HOCHTIEF Construction AG jack-up platform Thor Description and technical data, Civil Engineering and Marine Works, (PDF file available online ; PDF; 117 kB)
- Verkehrsrundschau, May 10, 2010 Jack platform Thor
- Die Zeit, June 7, 2011: Bottleneck: There are too few platforms to set up the wind turbines. A visit to "Thor"