The topsides and jackets for two offshore substations serving the Gennaker offshore wind farm have departed the Netherlands for the German Baltic Sea, where they will be installed as part of the OST-6-1 offshore grid connection project.
OSS Zingst and OSS Darß sailed on 9 October 2026 from Schiedam and Vlissingen, respectively, following the completion of fabrication and load-out operations in September. The structures are being delivered for German transmission system operator 50Hertz.
The HSI Joint Venture, comprising Smulders HSM and Iv, is responsible for the engineering, procurement, construction, installation and commissioning of both offshore substations, including their topsides and jackets. Smulders HSM was formed through the integration of HSM Offshore Energy and Smulders.
The Zingst topside, fabricated in Schiedam, weighs approximately 4,700 t and measures 48 m in length, 33 m in width and 17.5 m in height. The structure was rolled out of the fabrication hall in February before being loaded onto a transport barge in September.
The load-out of the OSS Zingst and OSS Darß topsides followed the earlier transfer of their jacket foundations from the fabrication yards. With both topsides and jackets now dispatched, the project has entered the offshore transportation stage ahead of installation in the Baltic Sea.
Each substation has a capacity of approximately 450 MW. Together, they will form part of 50Hertz‘s OST-6-1 offshore grid connection, which has a maximum transmission capacity of 927 MW.
The grid connection will use three 220 kV alternating-current submarine cable systems to transmit electricity from the offshore substations to Germany’s onshore network. The offshore cable route will extend up to approximately 53 km, followed by around 35 km of onshore cabling to the Gnewitz substation in Mecklenburg-Western Pomerania.
Developed by Skyborn Renewables, the Gennaker offshore wind farm is located approximately 15 km north of the Fischland-Darß-Zingst peninsula in the German Baltic Sea. The project will comprise 63 Siemens Gamesa wind turbines, each with a maximum output of 15.5 MW, providing a total generating capacity of up to 976.5 MW.
The offshore substations will undergo installation following their arrival at the project site. Gennaker is expected to be fully operational by the end of 2028.
