Supporting a converter platform

Supporting a converter platform

Supporting a 9300 ton converter platform during construction and transportation. Commissioned by Heerema Zwijndrecht, Holmatro supplied  590 ton cylinders and a vari pump with 100 litres oil capacity.

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Commissioned by: Heerema Fabrication Group (HFG) 
Location: Zwijndrecht, Netherlands


Heerema Zwijndrecht fabricates offshore platforms, jackets and modules with a cumulative weight of over 550,000 tons. In 2013, the Heerema Fabrication Group built the largest offshore transformer station, the DolWin alpha-platform, for the DolWin1 project. This “sea socket” connects large wind turbine parks to the electrical grid and transmits about 800 MW of green power to the German high-voltage grid.

The topside of the DolWin alpha platform is 77 meters in length, 45 meters wide, and 42 meters in height. After installation, the five-deck platform rises 80 meters above the water surface. The topside weighing 9,300 tons sits on a support, a jacket, that Heerema built at their Vlissingen fabrication location.


Safe and controlled transportation of the 9300 ton topside on a Mammoet SPMT (self propelled modular transporter).


During construction and transportation the offshore structure is supported by 590 tons cylinders with a stroke length of 100 mm. A specially made vari pump with 100 litres oil capacity controls the cylinders.

Watch the load out of the DolWin alpha topsides at Heerema's Zwijndrecht yard: