Device and method for erecting at sea a large slender body, such as the monopile of a wind turbine
The invention relates to a method for erecting at sea a large slender body, such as the monopile of a wind turbine. The method comprises bringing the large slender body in a substantially horizontal floating condition at least partly underneath the work deck of a platform, attaching a tension cable to the slender body, and pulling on the tension cable using fixations means and guiding means that are provided at an edge of the work deck and are connected to it to gradually bring the slender body in an erected position along the edge of the work deck. The slender body is optionally driven into the under water bottom. The invention also relates to a device for performing the method. The method is reliable and obviates the use of large cranes.
1. A method for erecting at sea a large slender body, the method comprising:
providing a device having a jack-up platform provided with spud poles for taking support onto an underwater bottom, and with a work deck to which are connected fixation means for a tension cable and guiding means that are provided at an edge of the work deck, the fixation means and guiding means being positioned at work deck height, whereby in operation the tension cable is attached to the fixation means, is guided along the guiding means and attached to the large slender body, the fixation means being adapted to lengthen or shorten the tension cable;
with the platform in a jacked-up position, bringing the large slender body in a substantially horizontal floating condition at least partly underneath the work deck of the platform such that a top end thereof is underneath the edge of the guiding means;
attaching the tension cable to the slender body; and
pulling on the tension cable using the fixations means and thereby;
gradually bringing the slender body in an erected position along the edge of the work deck; and optionally
driving the slender body into the under water bottom.
2. The method according to claim 1 , wherein to the work deck are connected further fixation means for a further tension cable, and further guiding means that are positioned at an edge opposite the edge of the guiding means, whereby in operation the further tension cable is attached to the large slender body at a rear end thereof, and the further tension cable is lengthened or shortened by the further fixation means.
3. The method according to claim 1 , wherein the fixation means comprise first and second fixation means, and wherein the tension cable is attached to the first fixation means, is guided along the guiding means and around attachment means, provided on the large slender body and led back along the guiding means to the second fixation means to form a sling.
4. The method according to claim 3 , wherein the device comprises two pairs of first and second fixation means, and two tension cables that are each attached to the first fixation means of a pair, guided along the guiding means and around attachment means, provided on the large slender body and led back along the guiding means to the second fixation means of a pair to form a sling.
5. The method according to claim 1 , wherein attachment means of the large slender body are located between the top end thereof and its center of gravity.
6. The method according to claim 1 , wherein the slender body is a monopile for a wind turbine and is driven into the under water bottom by a hydraulic hammer.
7. The method according to claim 1 , further comprising the step of connecting a wind turbine to the erected slender body.
8. The method according to claim 1 , wherein the fixation means comprises winches.
9. The method according to claim 2 , wherein the fixation means comprises winches.
10. The method according to claim 2 , wherein the further fixation means comprises winches.
11. The method according to claim 1 , wherein the fixation means comprises a movable pulley.
12. The method according to claim 2 , wherein the fixation means comprises a movable pulley.
13. The method according to claim 2 , wherein the further fixation means comprises a moveable pulley.
14. The method according to claim 1 , wherein the fixation means comprises a compound pulley.
15. The method according to claim 2 , wherein the compound pulley comprises a block and tackle.
16. The method according to claim 2 , wherein the fixation means comprises a compound pulley.
17. The method according to claim 16 , wherein the compound pulley comprises a block and tackle.
18. The method according to claim 2 , wherein the further fixation means comprises a compound pulley.
19. The method according to claim 18 , wherein the compound pulley comprises a block and tackle.
20. The method according to claim 1 , wherein the guiding means comprises a hoist bracket that extends over the edge of the work deck and is provided with a sheave.
21. The method according to claim 1 , wherein the platform comprises additional spud poles arranged at the edge of the work deck on both sides of the guiding means and in proximity thereof.