Allseas has completed transport and installation of the Gennaker offshore substations OSS Zingst and OSS Darß and their suction bucket jackets for 50Hertz in the German Baltic Sea.
The work was carried out by Pioneering Spirit in one offshore campaign. Allseas said the vessel’s jacket lift system (JLS) installed both the supporting jackets and the topsides, using an arrangement developed to accommodate shallow water at the site.
Installation began with placing the jackets on the seabed and securing them using suction. The topsides were then lifted into position on the foundations. 50Hertz announced that the installation had been completed in a statement dated 19 October 2026.
The structures were supplied by the HSI Joint Venture, which comprises Smulders HSM and Iv. Its contract covers engineering and procurement, fabrication, transport, offshore installation and commissioning.
In its 9 October announcement, the joint venture reported that the structures had departed the Netherlands. The Zingst topside and jacket sailed from Schiedam, while the Darß structures left Vlissingen.
Both substations form part of the OST-6-1 connection serving Gennaker. They will collect electricity from 63 wind turbines and increase its voltage from 66 kV to 220 kV. Power will then travel through three cable systems to the coast and onward to the Gnewitz substation.
The OST-6-1 grid connection has a design transmission capacity of 927 MW. Its cable route comprises up to 53 km at sea and around 35 km on land. 50Hertz said the grid connection system is scheduled to enter service in 2028.
