Ship and Method for Conveying and Setting Up Offshore Structures

Abstract

A ship according to the invention for conveying and setting up offshore structures having:

• • a hull with a U-shaped cross-section having an open stern and projections of the side walls extending at the rear beyond the rear edge of the floor,
  • jack-up leg systems with jack-up legs integrated in the hull that are movable in a vertical direction with their bottom ends in positions below the floor, and
  • a crane that can move on the top edges of the side walls.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]Not applicable.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH[0002]Not applicable.BACKGROUND OF THE INVENTION[0003]The invention relates to a ship and a method for conveying and setting up offshore structures. The ship and the method are especially intended for conveying and setting up offshore wind turbines.[0004]Operating wind turbines on the sea promises a high energy yield due to high average wind speed. Consequently, more offshore wind turbines should be set up. In the North Sea, several large areas have been designated for setting up wind turbines. These are generally located outside of the 12-mile zone. The depth of water is 10 meters to a few multiples of 10. It frequently ranges from 40 to 50 m.[0005]When setting up the offshore wind farm Alpha-Ventus, wind turbines were set up using the Thialf platform by the Dutch company Heerema. This is a very large piece of equipment that is typically used to set up oil platforms. The piec...

AI Technical Summary

Benefits of technology

[0035]According to one embodiment, the ship is immersed more deeply when it is fixed to the floor of the ocean by flooding the ballast tanks. The floor of the ocean is thereby compressed below the jack-up legs to provide a solid base.

[0036]According to another embodiment, the ship is lifted with the jack-up legs with the hull at least partially out of the water. This increases the load on the jack-up legs and fixes the ship more securely to the ground. When the hull is lifted only partially out of the water with the jack-up legs, the buoyancy acts on the hull. This relieves the jack-up leg systems so that they do not have to be as strongly dimensioned as is the case with a ship with a hull that can be completely lifted out of the water with the jack-up leg systems.

Problems solved by technology

However, it only takes one to two days to set up an offshore wind turbine, and then the platform needs to be towed to another setup site.

It is too time-consuming and expensive to use this piece of equipment to set up wind turbines.

A disadvantage with this special ship is that the wind turbines need to be transported ready assembled on their foundation so that the cargo projects high above the ship.

The stability of the ship is increasingly impaired as the height or respectively number of wind turbines positioned on the ship increases.

This limits the transportation capacity and possible uses of the ship.

The ship is only suitable for transporting the mast of a single wind turbine.

This is problematic when numerous wind turbines need to be set up as is the case with wind farms.

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