Jan De Nul Group has signed an agreement with Osbit Ltd (UK) for the design and construction of a new subsea trenching vehicle, named Swordfish. The high-powered subsea trenching vehicle can be fitted with either a jetting installation, a mechanical chain cutter or a combination of both to tackle a wide variety of soil conditions.
The Swordfish will be able to bury cables up to 3 or even 3.5 metres deep. Delivery is scheduled for the first quarter of 2022.
‘The Swordfish makes the perfect addition to our existing fleet of trenching vehicles providing excellent protection for cables installed by any of our cable laying vessels,’ says Wouter Vermeersch, Manager Offshore Cables at Jan De Nul Group. ‘With its high power, the Swordfish will be able to bury the cables deeper and thanks to its hybrid mechanical chain cutting configuration, the Swordfish can also tackle more challenging soil conditions, including hard clays up to 400 kPa. This new investment, together with the recent acquisition of our cable installation vessel Connector, arms Jan De Nul Group for the energy transition of tomorrow.’
Jetting, mechanical and hybrid mode
The Swordfish will be powered by 2 x 300 kW hydraulic power units and 2 x 300 kW electric HP jet pumps. In jetting configuration, it will be capable of tackling soil strengths up to 125 kPa, thanks to its 1120 kW of pump power. In mechanical or hybrid mode, it will be able to cope with soil strengths up to 400 kPa, using its 400 kW chain cutter tool and 420 kW additional jetting power.
The main jetting tool is combined with front cutting nozzles and additional rear backwash swords to optimise trenching performance. Thanks to the modular buoyancy, the underwater weight of the vehicle in jetting mode is less than one tonne, resulting in a ground pressure not exceeding 5 kPa which allows trenching vehicle operation in very soft soil conditions.
The innovative chain cutter design and cable loading system minimise cable handling, plus it has the added benefit of a closed box depressor to guarantee first-time-right protection.
The trenching vehicle will be launched with a dedicated A-frame and hoisting winch from one of Jan De Nul’s offshore vessels.
Sunfish and Moonfish
Specifically for the Race Bank Offshore Windfarm Export Cable project in the UK, Jan De Nul designed and built two intertidal trenching vehicles Sunfish and Moonfish that achieved an environmental and industry first. Both trenching vehicles received several industry awards for their innovative design and have subsequently been modified and used in support of several cable installation and protection projects in Europe.