/ Motion Compensated Pile Grippers

Offshore wind turbines are getting both larger and heavier. And, with the significant ambitions of the sector, wind farms are set to be installed in deeper waters. Floating vessels will have a role to play in the turbine installation of the future, being free from depth limitations and able to offer the increased crane capacity required for larger, heavier monopiles.

Increased workability

Floating vessel installation offers certain advantages. Increased workability is an example. A floating vessel has no requirement to jack up before performing installation. It can also offer increased payload capacity and support a heavier crane as weight is less of an issue.

There are, however, a number of associated challenges. Amongst these are the dynamics of the monopile. Vessel motions and wave forces can excite the monopile into oscillation.

Answering the challenges of the next generation

A solution to this is the Motion Compensated Pile Gripper. The gripper prevents the monopile from uncontrolled oscillation during lowering and piling and keeps it vertical by compensating the vessel motions in the horizontal plane. The gripper can also double as an upend tool to facilitate pile handling, thus saving on deck space.

The Motion Compensated Pile Gripper features a gripper ring system suspended from an XY-frame for translation in the horizontal plane. The gripper ring interfaces with the monopile, compensating for vertical vessel heave, roll, pitch and yaw.

Positioned on deck rails and providing the interface between the vessel and the gripper ring system, the XY-frame compensates for vessel motions in the horizontal phase – surge and sway, as well as DP drift.

Highly accurate installation

For the gripper to perform with the accuracy required for turbine installation, the XY-frame must offer low friction. Huisman has developed its own Linear Bearings to ensure this. This compact design offers easy access, low maintenance and long-life durability.

Ensuring safe working

Safety is paramount in the design of Huisman’s Motion Compensated Pile Grippers. Based on the philosophy that no single point of failure can result in a hazardous situation, a high level of redundancy has been incorporated into the grippers.

In addition to high levels of redundancy, Huisman Motion Compensated Pile Grippers also feature a monopile emergency release system to further ensure safe operations.