On behalf of DEME Offshore, heavy lift contractor Scaldis was responsible for the transport and installation of the Mermaid & Seastar offshore substations (OSS) in the Belgian North Sea in March 2020.
Specifically for this project Scaldis developed a new record-breaking transportation/installation method for the two 1200-ton topsides. Both topsides, with highly sensitive equipment on board, were picked-up by crane vessel Gulliver in a sheltered port and were seafastened on deck. A modular seafastening was designed and built to transport the topside partially suspended in the main cranes to the SeaMade offshore wind farm. The OSS was maintained into the cranes during transport to optimize the lean and cost-effective seafasting configuration. This innovative method eliminated the endeavor of mooring, offshore barge and the need of auxiliary tugs.
Amsterdam based Marine Engineering Consultant Mocean Offshore worked closely together with Scaldis during the development of this new concept using an advanced software package analysing the motions of the loaded Gulliver in different weather and wave conditions during the transport phase from Vlissingen to their final destination in the Belgian North Sea.
Jelte Kymmell, managing director of Mocean Offshore: “We were very pleased that we could participate in the transport and installation of these new Belgian offshore windfarms. Our key challenges were the partially suspended topsides, the interface with the seafastenings and implementing forward speed. The determination of the forces that the OSS could exert on the deck of the Gulliver during transport was decisive for Scaldis when designing the seafastenings. It is very satisfying to see that we were able to give Scaldis the confidence to manage risks during the complete transport and installation operation, reduce inefficiencies, and validate their seafastening design. We look forward to seeing the SeaMade windfarm fully in operation, contributing to a world with cleaner energy.”