Sleipnir Installs First Hornsea 3 Offshore Substation Jacket Foundation

Heerema Marine Contractors has installed the jacket foundation for the first Hornsea 3 offshore substation using its semi-submersible crane vessel (SSCV) Sleipnir.

According to a Notice to Mariners issued by the project on 20 March, Sleipnir commenced the work at the construction site offshore the UK on 19 March. The notice states that the vessel had started the “installation of Offshore Converter Station 1 (OCS1)” and that the campaign was expected to last approximately 3-5 days.

The vessel’s AIS data available online shows that Sleipnir is now in the port of Stavanger, Norway.

Heerema Fabrication Group, which was contracted in 2022 by Aibel to design and fabricate jackets for the two Hornsea 3 OCS platforms, said on 24 March that it had completed the jacket foundation for the first offshore substation, Link 01, and that the substructure was towed to SSCV Sleipnir on 18 March.

The topside for the first substation, built by Aibel and Hitachi Energy, arrived from Thailand to Norway in June 2025, with the second topside following suit in October last year.

Heerema is now working on the second jacket, Link 02, which is scheduled to be completed in August 2026.

The 2.9 GW Hornsea 3 offshore wind farm, being built approximately 160 kilometres off the Yorkshire coast, is Ørsted’s third gigawatt-scale project in the North Sea’s Hornsea zone. The offshore wind farm, which will feature Siemens Gamesa’s 14 MW turbines, is expected to be operational in 2027.

For Sleipnir, the world’s largest SSCV, the work offshore the UK follows the installation of the jacket foundation for the BorWin kappa platform, part of TenneT’s BorWin6 offshore grid connection in the German North Sea.