Jan De Nul Group, a premier marine contractor, made significant achievements in Europes energy transition during December 2025. They completed critical cable installation works and advanced their fleet capabilities - cementing their position within Europes energy transition process.
DolWin Kappa Installation Campaign Completed Successfully
On 17 December 2025, Jan De Nul announced the successful conclusion of its transport and installation campaign at TenneTs DolWin kappa offshore substation in Germany's North Sea. Working closely with Hellenic Cables, Jan De Nul was responsible for designing, production, transport, installation and protection of three 155kV HVAC cables totaling 37 km that connect the offshore converter station with Nordseecluster 1 and 2 wind farms as well as supporting Gode Wind 3 project with an aggregate capacity of 900MW.
Cable-laying vessel Isaac Newton transported the cables from Hellenic Cables plant in Corinth, Greece, and installed them, including concrete mattresses at subsea crossings. Multi-purpose vessel Adhémar de Saint-Venant buried the cables using its UTV1200 trencher. In the final phase, rock installation vessel Simon Stevin placed about 25,000 tonnes of rock berms for seabed protection. Spring 2026 will see final connections and testing after the wind farm stations installation.
Jan De Nuls is providing continuous services to TenneT, including future export cable works planned for two GW converter stations linking Germanys onshore grid. As part of DolWin6, renewable power equivalent to 1.1 million homes will be made available.
Launch of World's Largest Cable-Laying Vessel
Jan De Nul launched its newest flagship, the Fleeming Jenkin, by flooding the dry dock at CMHI Haimen shipyard in China, as reported around 4-21 December 2025. This vessel represents the pinnacle of the companys in-house design expertise, combining 15 years of cable installation know-how.
Equipped with three cable carousels that boast 28,000 tonnes capacity - twice what most competitors can handle - this vessel can simultaneously lay four cables. Tensioners support shallow and deep-water installations via chute and cable-laying wheel. As an Ultra-Low Emission vessel with hybrid power, its exhaust filters reduce nanoparticles by 99 percent; biofuel and green methanol compatibility; as well as biodiesel compatibility for efficient use; it features dual exhaust filters reducing nanoparticles by 99 percent as well as biodiesel compatibility; all this vessel needs is a 2.5MWh battery for efficiency!
Fleeming Jenkin heads straight to TenneTs 2 GW Program, installing 2,800 km of subsea cables for next-generation grid connections exceeding 2 GW capacity. A twin vessel, William Thomson, and new rock installer George W. Goethals with 30,000-tonne capacity for depths up to 400 m, enhance subsea protection against threats like sabotage.
Contract for Formosa 4 Offshore Wind Farm.
Jan De Nul secured a contract with Synera Renewable Energy for installing export cables at the Formosa 4 offshore wind farm off Miaoli County, Taiwan. The scope covers 60 km of subsea HVAC cables to shore from the 495 MW project with 35 turbines. Construction starts in 2026 using cable-laying vessel Willem de Vlamingh, extending into 2027.
Additional developments. (see Related Developments ).
Jan De Nul announced on 11 December 2025 the launch of an advanced simulator for wind farm installations at sea, improving dredging and offshore capabilities. On 4 December 2025, Borkum Riffgrund 3 wind farm linked to prior Jan De Nul works delivered its initial energy. These events demonstrate Jan De Nul's momentum in renewable infrastructure amid rising subsea cable demand to support 355 GW of European offshore wind by 2050.