Hollandse Kust Offshore Windfarm

Case Study Overview

The Consortium Jan De Nul and LS Cable (JLC) was awarded the supply and installation of high voltage cables for the grid connection of the Dutch offshore wind farms Hollandse Kust Noord and West Alpha. The connection consists of four cable systems with a total length of 210km that connect the wind farms to the onshore Dutch power grid near Beverwijk, just north of the Port of Ijmuiden.

At a glance

  • Location: Hollandse Kust Offshore Windfarm, Netherlands
  • Plant used: 400T Haven SeaSeven
  • What we did: Red7Marine supported Jan De Nul with the offshore windfarm cable landing at Hollandse Kust.
hollandse kust


Jan De Nul Group chartered Red7Marine’s 400t Haven SeaSeven jack-up barge for the export cable installation to act as a tensioner station to reduce the total export cable tension.

Red7Marine’s in-house team of engineers carried out a full vessel site specific assessment and leg penetration assessments for the project completed to ISO19905 standards.

The barge was mobilised in the Port of Tilbury and towed into the Port of Ijmuiden ahead of operations commencing. Red7Marine also supplied Barge crew throughout the duration of the project.

hollandse kust challenge


Red7Marine began working with Jan De Nul early in 2021 and as a part of the project, our in-house team designed, fabricated and installed a cantilever platform and cable highway system which was welded on to the barge in Tilbury before its departure to support the tensioning operations.

On-site works began in April 2022. The SeaSeven was positioned in the nearshore intertidal area and supported the HDD system from landside to the beach with Jan De Nul using its trenching vehicle the ‘moonfish’ to trench the cable 5m below seabed.

The barge worked alongside MPI Offshore‘s Adventurer cable laying ship which was being used to winch the cable back to shore.

hollandse kust solution

hollandse kust solution




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“Falmouth Divers Ltd contracted Red7Marine at the end of 2019 to undertake the installation of two rock-socketed piles at the Jupiter Point Royal Naval training facility near Torpoint. Red7Marine mobilised its SeaSeven jack-up vessel from Liverpool and transited it to Plymouth in early January through a gap in the seasonally bad weather. The mobilisation was conducted efficiently within a week as planned.”

Garry Duff, Engineer Falmouth Divers