On 17 November 2022, Jan De Nul Group completed the first part of the cable installation works to connect the wind farms Hollandse Kust (noord) and (west Alpha) to the Dutch mainland. Also the 220-kV high-voltage tests of both sea and land cables for Hollandse Kust (noord) were successfully completed, from the onshore substation to the substation located 18 km offshore, according to the company's release.
Also on 24 November, Jan De Nul signed a contract with Global Marine Systems Ltd. for the acquisition of the Offshore Support Vessel Global Symphony. This marks a further investment in the offshore installation capacities of the Luxembourg-based maritime contractor.
The cable installation vessel Isaac Newton installed the cables on the seabed. In addition, Jan De Nul used several remote-controlled underwater trenchers and amphibious cranes in the surf zone to bury and protect the cable in the seabed. The Moonfish is one of these trenchers, a Jan De Nul design tailored to the needs of this project.
In the spring, the cable installation vessel Isaac Newton collected the first lot of 90 kilometres of sea cable from our consortium partner LS Cable & System in South Korea. After arriving in the Netherlands, the Isaac Newton installed four different sea cables, starting from the beach.
Next, the trencher Moonfish set to work, burying and protecting the sea cables in the seabed. In the first phase, the Moonfish buried the first section of the two Hollandse Kust (noord) sea cables in the seabed, from the beach up to 3 kilometres offshore, at a depth of about 6 to 8 metres. From three kilometres offshore, the submarine vehicle UTV1200 took over, laying the cable up to the transformer station. This 'offshore socket' is located 18 kilometres off the Dutch coast.
After the summer high season, in October, Jan De Nul completed this first installation campaign by burying the two cable sections for Hollandse Kust (west Alpha) from the beach up to 3 kilometres offshore.
The Moonfish on wide tracks has been designed and made to lay cables underwater, up to 35 metres deep. With its long metal sword and powerful water jets, the Moonfish buries the cables in the seabed. A floating water pipe pumps water to the powerful water jets on the Moonfish's long metal sword. With this, the Moonfish makes a deep trench in the seabed, where it simultaneously lays the cable at a depth of up to 8 metres. The trench is then immediately backfilled. As a result, the cables are safely protected against future coastal erosion.
In total, Jan De Nul is installing four sea cables in three installation campaigns. These sea cables will connect the transformer stations of the two wind farms Hollandse Kust (noord) and (west Alpha) to the mainland. Each transformer station will receive two cables, all together accounting for a total cable length of 235 kilometres.
Jan De Nul still needs to install two more cable sections to connect the future wind farm Hollandse Kust (West Alpha) to the grid. Jan De Nul's cable installation vessel Connector will collect the first in South Korea, transport it to the Netherlands and then install it. The Isaac Newton will again be deployed for transporting and installing the final sea cable section.
Built in 2011, the Symphony has an extensive 1,400 m² deck space and is amongst others equipped with two 150 HP work class ROV systems and a 150 tons AHC crane. Thanks to the design of the vessel, the Symphony can operate in higher seastates.
The Symphony will predominantly be used to support cable installation activities and will operate as a dedicated Trenching Support Vessel. Company's recently delivered state-of-the-art newbuilt trencher Swordfish will be installed on board of the Symphony by the first quarter of 2023.
Jan De Nul Group operates today a very modern and balanced offshore fleet, comprising this offshore support vessel, two offshore jack-up installation vessels, three floating crane installation vessels, three cable-lay vessels, five rock installation vessels and two multipurpose vessels.