Noise Mitigation Screen Ballast Box for Monopile Installation

About Noise Mitigation Systems

In today’s maritime market, different types of Noise Mitigation Systems could be distinguished. Amongst others: screens with Hydro Sound Dampers (HSD) or systems using Helmholtz Resonator Blocks. Both types of sound damping solutions have been successfully integrated into customers' monopile installation equipment by our department Equipment Design. 

Project case: DEME Group HLV Orion

DEME Group is installing monopiles using their Heavy Lift Vessel (HLV) Orion. A Motion Compensated Pile Gripper (MCPG) and an impact hydraulic hammer are used for installation of monopiles onto the seabed. To minimise side effects of the installation, a noise reduction system in the form of an HSD screen is deployed. 

To lower down and retrieve the screen, a ballast box and winch supports have been designed by Vuyk Engineering Rotterdam. The ballast box functions as a box to catch and store the HSD screen. It needs to have sufficient weight to pull the floating screen to the seabed. The ballast box is attached below the MCPG, and is lowered and retrieved with hydraulic winches. The winches are placed on dedicated support structures that fit on the MCPG, without interfering other components. 

When the ballast box is lowered onto the seabed, swell compensators will function as cable tensioners. The winches pay out wire until the swell compensators vary in position around their midstroke. From then on, vessel motions are compensated passively by the swell compensators. The swell compensator cylinder is connected to hydraulic accumulators.

Equipment Engineering Challenge

The Equipment Design scope required to have openable doors for loading a new monopile onto the gripper and to allow for emergency retrieval when a monopile is installed. The ballast box is therefore equipped with special hinges that allow for a certain movement of the doors when the ballast box is lowered through the splash zone. The doors are locked with a mechanical door lock and automatically unlock when the ballast box is lifted against the bottom of the gripper.

Noise Mitigation during installation

Noise Mitigation Systems have been used successfully in a number of offshore wind farm projects around the world. By reducing the noise generated during monopile installation, these systems can help to protect marine life and reduce any impact. The systems are important tools in the development of offshore wind farms, and will likely become more widely used as the industry continues to grow. 

Deme Group