The topsides and jackets for OSS Zingst and OSS Darß have departed from the Netherlands for installation in the Baltic Sea, a sail-away that the HSI Joint Venture describes as a major milestone in the delivery of 50Hertz's OST-6-1 offshore grid connection. The project will connect the Gennaker Offshore Wind Farm to the 50 Hertz transmission system on land.

According to an announcement on 9 October 2026, the departures mark the transition from engineering, construction, and integration (EPC) towards transport, offshore installation, and commissioning in the German Baltic Sea.

Powering the Gennaker Offshore Wind Farm

As part of OST-6-1, OSS Zingst and OSS Darß will transmit power from the 927 MW Gennaker Offshore Wind Farm in the German Baltic Sea towards the onshore grid connection.

The project forms part of the continued expansion of offshore energy infrastructure in the German Baltic Sea, which the company situates in the context of Europe's changing energy system, where growing electricity demand and the shift of industries, transport systems, and households towards low-carbon power must be matched by reliable grid infrastructure.

Each of the two offshore substations has a capacity of approximately 450 MW.

Full EPCIC Responsibility under the HSI Joint Venture

The HSI Joint Venture brings together Smulders HSM and Iv. Together, the partners are responsible for the complete EPCIC scope of the topsides and jackets for OSS Zingst and OSS Darß, covering engineering, procurement, construction, transport and installation, and commissioning. This integrated approach combines offshore engineering expertise, steel fabrication, systems integration, and project execution within one delivery team.

The successful load-outs and sailaways follow an extensive period of engineering, procurement, fabrication, assembly and integration across two locations.

Two Yards, One Offshore Destination

The topside and jacket for OSS Zingst departed from Schiedam, while the topside and jacket for OSS Darß sailed from Vlissingen. Built and integrated across the two Dutch yards, both offshore substations are now moving into the next project phase.

Industry Voices on the Achievement

Hans Leerdam, Commercial Director at Smulders HSM, said the sail-away of OSS Zingst and OSS Darß is an important milestone for everyone involved.

He noted that delivering two complete offshore substations of this scale requires close integration across engineering, procurement, fabrication, systems integration, and offshore execution, and that seeing the topsides and jackets depart reflects the expertise, commitment, and collaboration of the teams within Smulders HSM and Iv, together with the client and project partners.

Fedor van Veen, Managing Director Offshore & Energy at Iv, said the sail-aways show what it takes to turn complex designs into reliable offshore infrastructure, citing constant alignment between design and construction across multiple teams and locations. Bringing everything together at this scale, he said, is a strong achievement and a clear example of what European industrial cooperation can deliver.

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