Allseas secures installation contract fo DolWin4 and BorWin4 converters

4C Offshore | Tom Russell
By: Tom Russell 25/01/2023 Allseas

Allseas has been selected to install the high voltage direct current (HVDC) converter platforms for the DolWin4 and BorWin4 offshore grid connection projects in the German North Sea.

Awarded by Dragados Offshore, the contract covers the transport and single-lift installation by
Pioneering Spirit of two 900 MW converter stations for the transmission of wind-generated power.

DolWin4 and BorWin4 are the first offshore grid connection systems to be developed by German transmission system operator Amprion Offshore GmbH. Dragados Offshore is responsible for delivering the two platforms, with partner Siemens Energy providing the HVDC technology.


Both the DolWin4 and BorWin4 platforms will be built in Cadiz, Spain, and transported by Allseas cargo barge Iron Lady to Rotterdam for transfer to Pioneering Spirit.

The structures comprise topsides weighing approximately 12,500 tons, supported by 7,000 ton (DW4) and 8,000 ton (BW4) jackets. Installation is scheduled for 2027.

This contract continues the collaboration between Dragados and Allseas, following transport and installation awards for HVDC converter platforms for the DolWin6 and BorWin5 offshore wind grid connections.

Vice President Projects, Matthijs Groenewegen, said: “Countries like the Netherlands and Germany have set ambitious targets for offshore wind development, with operators fast-tracking plans for next generation offshore grid systems supported by supersized converter stations.

“These are substantial structures, ideally suited to our unique transport and single-lift installation capabilities. We showed what we are capable of with DolWin6 last year and the market has taken notice. As the size of converter stations increases, so does the argument for our significantly safer, faster, and more efficient single-lift solution.”