Europe needs fresh electrical arteries under the sea - and it needs them quickly. A cable‑laying vessel built in Belgium, Fleeming Jenkin, is now being positioned to stitch those links across the North Sea.
A record-bending vessel with one job
Jan De Nul, the Belgian family-owned group established in 1938, presented Fleeming Jenkin on 21 October 2025. The vessel is about 200 metres long. It can carry as much as 28,000 tonnes of high‑voltage cable across three carousels. In practical terms, that load equates to roughly 2,800 kilometres of cable - enough to run a single continuous length from Paris to Istanbul.
The brief is straightforward: install heavy subsea power cables that bring electricity from offshore wind hubs into onshore transmission networks. Early work is tied to TenneT’s 2 GW programme, the German‑Dutch effort to standardise very large, high‑capacity connections in the North Sea. Each 2 GW link delivers a continuous power flow on the order of two nuclear reactors.
"28,000 tonnes of cable on board. Up to four lines deployed at once, held under 150‑tonne tension for precise placement."
Rather than chasing cruise‑ship scale for its own sake, the design pushes the category in the areas that matter for cable work: steadiness, usable deck area, carousel capacity, and the ability to operate in rough conditions while holding accuracy down to very small margins.
Precision at sea, engineered end‑to‑end
Jan De Nul says it developed the full operating “stack” internally. That includes the control software, line‑up and alignment equipment, and motion‑compensation systems intended to keep the lay route on target. Two carousels are located on deck and one sits below, allowing several cables to be paid out under controlled speed and tension. Instrumentation monitors bend radius and torsion continuously. Remotely operated vehicles (ROVs) observe the touchdown point on the seabed and enable route adjustments metre by metre.
The installation spread is rated for operations down to 3,000 metres. That means the same vessel can move from near‑shore export sections to deeper crossings without changing to a different platform - saving project time and reducing exposure to poor weather.
"Software, carousels, ROVs and deck handling work as one system, tuned to keep every tonne of copper and steel in the safe window."
Cleaner engines for heavy work
The ship will begin operations as an Ultra‑Low Emission Vessel. A 2.5 MWh battery is used to shave peak demand and steady onboard power for deck operations. The generators are set up to run on biofuel as the default, and the configuration is methanol‑ready for green methanol once supply chains can support it. A dual exhaust after‑treatment system removes up to 99% of nanoparticles. Together, these measures cut local emissions and reduce fuel use during dynamic positioning and high‑tension cable work.
This is presented as more than a symbolic feature. Cable laying involves long periods holding station, intensive winching, and slow, precise manoeuvring. Hybridised power helps smooth those fluctuating loads and can save tonnes of fuel week after week.
Weaving the European supergrid
By mid‑century, Europe is aiming for a network of interconnectors and offshore hubs. ENTSO‑E estimates that around €400 billion will be invested in subsea connections and grid strengthening by 2050. These links are intended to shift wind-generated surpluses between countries and deliver low‑carbon electricity to industrial centres that require it.
Fleeming Jenkin will be part of a wider fleet effort. A sister vessel, William Thomson, is planned to support the programme as well. Between them, the focus includes routes linking Denmark, Norway, Germany, France and the UK. Cable protection capacity is expanding too: another newbuild, George W. Goethals, is designed to transport 30,000 tonnes of rock for armouring cables against anchors, trawling activity and severe weather.
| Key figure | Fleeming Jenkin |
|---|---|
| Length | ~200 m |
| Cable payload | 28,000 tonnes |
| Carousels | 3 (two on deck, one below) |
| Simultaneous lays | Up to four cables |
| Max lay tension | ~150 tonnes |
| Depth capability | Up to 3,000 m |
| Battery energy | 2.5 MWh |
| Fuel pathway | Biofuel today, methanol‑ready |
| Emissions control | Dual exhaust, 99% nanoparticle removal |
Why cable layers became the bottleneck
Offshore wind capacity grew faster than the grid equipment needed to connect it. Turbines went into the water quickly, while grid operators are now racing to catch up. Production of high‑voltage cable is running close to maximum capacity, and the number of specialist installation ships remains limited - with vessels booked far in advance.
- Standardised 2 GW platforms push up cable lengths per scheme and require higher voltage levels.
- HVDC export cables demand strict control of temperature, bend radius and burial depth.
- Seabed survey campaigns take time, but they reduce the risk of strikes and overheating.
- North Sea weather windows are narrow, increasing the premium on large, stable ships.
- Repairs depend on vessel availability, because one failed joint can mean millions per day in lost electricity delivery.
"Grid cables act as the invisible arteries of the energy transition. When they stall, projects stop and power stays offshore."
France stays influential behind the scenes
Vessel size is only one way the market is measured; industrial control is another. France retains a strong foothold across the subsea cable chain. Four names are highlighted: Nexans, Orange Marine, Louis Dreyfus Armateurs and Alcatel Submarine Networks. Collectively, they cover design, manufacturing, installation and maintenance for power and telecoms cables worldwide.
French operators also command a significant portion of global cable‑laying capacity. Industry figures for 2025 indicate that roughly one third of worldwide cable‑lay ship tonnage sits under French control, which helps secure access to lengthy construction campaigns and scarce repair slots.
What it means for the UK
The UK sits at the centre of this build‑out. Britain is set to expand offshore wind generation while also strengthening interconnector capacity with neighbouring systems. Belgian, French and British fleets will share workloads across export corridors, offshore hubs and subsea data infrastructure.
Ports from the Humber to the Tyne already handle cable drums, jointing facilities and ROV support. The larger carousels used by high‑capacity vessels require quays with sufficient load limits and ample laydown space. Securing port slots early increasingly shapes delivery dates. For the UK supply chain, more high‑capacity ships working in the North Sea can reduce downtime and make repair mobilisation quicker when faults occur.
How a 2 GW link gets from factory to seabed
Cable plants manufacture long continuous lengths using large rewinding systems. Onboard the vessel, the cable is loaded into the carousels in a controlled spiral. Before sailing, the team checks insulation integrity and measures conductor resistance. Offshore, survey crews re‑confirm the trench route and identify hazards. A plough opens a narrow trench while the ship pays out cable at a matching rate. Sensors maintain lay tension at defined setpoints to protect both conductor and sheath. Joints are assembled on deck within climate‑controlled tents and then tested again. Burial tools then backfill to the specified depth to meet thermal requirements and provide protection.
At the end of the process, commissioning teams energise each pole, ramp up current and monitor temperature rise. Grid operators observe system behaviour and then approve handover into commercial service.
Risks and how crews manage them
- Anchor strikes: separating traffic and adding rock berms lowers risk in busy shipping areas.
- Fishing gear: defined burial depths and protective mattresses reduce snagging.
- Thermal limits: burial depth and seabed conditions govern heat dissipation along the route.
- Weather: strong dynamic positioning capability expands workable windows and cuts delays.
- Joint failure: factory‑made joints and controlled onboard environments improve reliability.
- Cyber and grid security: interconnectors rely on monitored repeaters and robust converter stations.
Why Belgium’s bet looks smart
Demand for high‑capacity cable‑laying ships is not expected to ease during this decade. North Sea hubs are moving towards standard 2 GW building blocks, and interconnectors are becoming longer and heavier. Fleeming Jenkin is aligned with that direction through its carousel capacity, precision handling and lower‑emission propulsion concept.
Jan De Nul is also positioning itself across more of the value chain. Pairing cable installation with a protection vessel able to place 30,000 tonnes of rock reduces reliance on external contractors. That combination can shorten delivery schedules and protect margins when subcontractor availability is tight.
Extra context for readers
High‑voltage export connections typically use DC because AC losses increase over long distances. HVDC systems operate at thousands of volts and rely on robust insulation with strict thermal limits. The cable’s copper or aluminium core must remain within defined temperature ranges, making burial depth and seabed thermal properties important.
Project teams are increasingly testing digital twins to model cable dynamics during installation and across the operating life. These simulations examine fatigue around touchdown zones, thermal cycling, and scour where currents reshape sandbanks. The outputs inform trench depth decisions, rock placement plans and long‑term inspection schedules.
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