Proven Onshore Technique Increases Offshore Efficiency
Mammoet Europe has successfully concluded the lifting and handling of the cabling equipment for the Nordergründe offshore wind energy project. By using a custom-built hoisting system instead of a floating sheerleg, Mammoet helped subsea power cable installation company VBMS to get the job done much more efficiently.
The Nordergründe offshore wind project needed an electrical cable to connect their offshore substation to the onshore power grid, so they contracted VBMS to install this 28km-long cable. VBMS planned on using their BSSII burial sledge system to put the cable into the seabed. The BSSII is a tool that creates a trench into the seabed by fluidising the soil and simultaneously laying the cable. During the project, VBMS would occasionally have to launch and recover the BSSII – something that would normally require a floating sheerleg. However, using a floating sheerleg would put severe restraints on the project. Letting a floating sheerleg can be quite costly and floating sheerlegs often have to be reserved well in advance. VBMS therefore involved Mammoet in the early stages of the project and asked them to come up with a smart solution for this problem.
“What we basically did is apply our land-based expertise to an offshore situation,” Commercial Manager Richard van Looij explains, “our ability to look at offshore challenges with a fresh set of eyes often helps us find smarter and faster solutions”. By combining two of the beams that were used for the lifting of the Kursk with three winches, Mammoet was able to equip a standard barge with a custom-designed system that could hoist the BSSII without the need for a floating sheerleg. This provided the client with a much more flexible and efficient method for hoisting the BSSII.
The hoisting system was also specifically designed to keep the installation time on the barge to a minimum. After a 12-day quayside assembly period the system was installed on the barge and fully operational within two days, allowing the client to minimise barge rental time and get the job done more efficiently.