Jan De Nul has launched the William Thomson, one of two identical subsea cable-laying vessels currently under construction in China. With a cargo capacity of 28,000 tonnes and a length of 215 metres, these vessels are described as the largest of their kind.
The Belgian firm said the two new vessels were built to install these cables in both shallow and ultra-deep waters reaching depths of 4,000 metres. The William Thomson is equipped with three cable carousels and a large hold for fibre optic cables, allowing it to lay four cables simultaneously.
The power plant on board is a hybrid system that combines generators with a 2.5 MWh battery and drive technology. Jan de Nul remarked that this setup is designed for peak shaving, load smoothing, and maintaining a spinning reserve while optimising engine loading.
Its sister vessel, Fleeming Jenkin, was launched in October 2025 and is scheduled for delivery in the final quarter of 2026.
Jan de Nul expects the William Thomson to follow shortly after with operations slated in the first half of 2027.
Once operational, the vessels will begin work on a two-gigawatt programme for TenneT, the grid operator for the Netherlands and parts of Germany. For this project, the Fleeming Jenkin and William Thomson will install more than 2,800 kilometres of 525 kV DC cables.
Jan De Nul will also deploy one of these vessels in 2028 to install three 220 kV AC cables connecting Belgium's Princess Elisabeth Island offshore wind project to the shore.
The company noted it is currently expanding its subsea cable capacity with five additional vessels under construction.
These include the two cable-laying ships, two trenching support vessels, and one rock installation vessel used to protect cables on the seabed.