Asso.subsea to Install Cables at Danish Offshore Wind Pair

Vattenfall has awarded Asso.subsea with a contract for the transportation, installation, protection and commissioning of the 66 kV export and inter-array cables for the Vesterhav Nord and Syd offshore wind projects in Denmark.


The overall system will comprise four export and 37 inter-array cables, for a total of more than 70 kilometres.

According to Asso.subsea, the submarine route is characterized by high technical challenges, including shallow water areas, boulder fields, mobile sediments, and a great variety of conditions from very soft to hard soils.

The company will use almost the full capacity of its fleet, including the DP2 cable laying vessel (CLV) Atalanti, and the DP2 trenching support vessels Argo and Aethra for the seabed preparation and post-lay burial operations.

The latest versions of the trenching machines from the AssoTrencher IV as well as the AssoJet III families will be mobilized in order to provide the required protection of the cables along the whole submarine route.

The completion of the project is expected by mid-2023.

“We are delighted for the opportunity to work with Vattenfall on a so prestigious project, after the positive experience on the Kriegers Flak boulder mitigation campaign,” said Ioannis Togias, director of the Marine Division of Asso.subsea. “With more than 40 M€ invested only in 2020 for the expansion and upgrades of our fleet, we are extremely proud to be able to support Vattenfall in another fundamental step towards the energy transition.”

Located nine and eight kilometers offshore respectively, Vesterhav Syd and Vesterhav Nord will comprise a total of 41 Siemens Gamesa 8.4 MW turbines with a combined capacity of 344.4 MW.

Hellenic Cables will deliver the inter-array cables for the two offshore wind farms, as well as the associated accessories, under a contract secured with Vattenfall in September.

Commissioning of the projects is expected by the end of 2023.

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