Jasmund Substation’s Topside and Jacket Sets Sail to Baltic Sea

Friday, December 5, 2025

The topside and jacket structure for the Jasmund offshore substation (OSS) have embarked on the journey to Baltic Sea for installation, following the completion of construction by the HSI consortium, formed by HSM Offshore Energy, Smulders and Iv.

The topside, measuring 48 metres by 33 metres and weighing about 4,500 tonnes, departed HSM Offshore Energy’s Stormpolder yard and travelled through central Rotterdam in a high-profile transit. The 72-metre-high jacket sailed from Smulders’ Vlissingen yard.

Both structures are now en route to the Baltic Sea, where Heerema Marine Contractors will install them northeast of the island of Rügen.

Once operational, the OSS Jasmund substation will have a planned capacity of 300 MW and will connect the Windanker offshore wind farm to the onshore grid.

The OSS Jasmund is being delivered for German transmission operator 50Hertz, with the consortium responsible for the full EPCIC scope. It is the first of three substations being developed for 50Hertz as part of the Ostwind 3 and OST-6-1 grid expansion projects.

 “The successful sail-away of the OSS Jasmund topside is a testament to the dedication, expertise, and seamless collaboration across the HSI consortium. Guiding such a massive structure through the center of Rotterdam was not only an impressive achievement but also a proud moment for everyone involved,” said Hans Leerdam, HSM Offshore Energy’s chief commercial officer.

Categories: Technology Offshore Renewable Energy Industry News Activity Europe Offshore Wind

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