Jan De Nul’s Fleeming Jenkin Begins Sea Trials Ahead of TenneT Assignment

1 September 2026
Edited By: Haley McQueen

Jan De Nul's latest extra-large cable-laying vessel, Fleeming Jenkin, has left the shipyard for its sea trials. This is an important milestone in the construction of the vessel: for the first time, Fleeming Jenkin is heading out to sea, and the company is putting it through extensive testing. The vessel will install subsea cables that connect offshore energy to the electricity grid. With a loading capacity of 28,000 tonnes, Fleeming Jenkin is also the largest cable installation vessel of her kind. Once the sea trials have been successfully completed, the vessel will be ready for delivery and can begin her first major assignment: TenneT's 2 GW program.

(Image credit: Jan De Nul)

And there is more to come: her twin vessel, William Thomson, is on schedule and is expected to follow Fleeming Jenkin soon. Together, they are among the most advanced vessels for installing interconnection cables, which connect energy networks over long distances.

More than 2,000 Tests at Sea

During the sea trials, the vessel leaves the shipyard, and Jan De Nul puts her through extensive testing at sea for the first time. Everything that cannot be tested alongside the quay is put through its paces: from performance and maneuverability to the various systems on board. It is an important dress rehearsal, allowing us to check that everything is working as it should and that the vessel is ready for her future assignments.

And this is done thoroughly. During the sea trials, more than 100 test procedures are completed, resulting in more than 2,000 individual tests. Each component is carefully checked and assessed.

165 Experts, One Mission

There is also plenty happening on board. A total of 165 people are taking part in the trials: 141 from the shipyard and 24 from Jan De Nul.

Each brings their own expertise, but everyone shares the same goal: to ensure that the vessel is fully ready to embark on her first real offshore assignment.

“The physical construction of the vessel started in November 2024, when there was essentially nothing there yet. Since then, we have watched her take shape step by step, from the first structures to the fully operational vessel that is now ready to head out to sea. That makes the sea trials a special moment for everyone who has contributed to this project over the past months and years. You can literally see all that hard work coming together. The sea trials are truly the culmination of everything we have achieved during this period,” said Pieterjan Storme, Senior Technical Superintendent.