Unrivalled capability was required for Hollandse Kust (Zuid) project, in which cables cross an important shipping lane
A uniquely capable trencher developed to bury cables serving the Hollandse Kust (Zuid) offshore windfarm was delivered to offshore contractor Van Oord earlier this year.
Designed and built for the company by Soil Machine Dynamics (SMD) in the UK, the Deep Dig-It trencher can bury cables to a depth of 5 m. The cables need to be buried to that depth because the cable route crosses the Rotterdam Maasmond shipping lane.
Deep Dig-It is a tracked remotely operated vehicle (TROV) designed to ‘drive’ across the seabed, creating a trench for the cables while simultaneously inserting the cable and then closing the trench again. The new machine is the largest and most powerful in its class. It weighs 125,000 kg, is more than 17 m long, well over 8 m high and 11 m wide. It has an installed power of 2,500 hp, which will enable it to bury cables into very hard, compacted soil.
Deep Dig-It is controlled by Van Oord’s offshore installation vessel MPI Adventure, which is equipped with a crane that launches and recovers it.
In February 2020, Van Oord completed installation of the cables for the Borssele I & II projects in the Netherlands. The company installed all 94 array cables connecting the turbines on Borssele I & II, completing the job ahead of schedule.
The cables for Borssele I & II were installed by Van Oord’s cable-laying vessel Nexus. Deep Dig-It was assigned to the cable burial campaign for the project, which was undertaken on behalf of developer Ørsted.
SMD refers to Deep Dig-It as a deep burial tractor 2400 (DBT2400). Delivery of the trencher followed the successful deployment of SMD’s QTrencher 1600 by Van Oord on an earlier Van Oord project.
The manufacturer said the DBT 2400 can actually achieve a 5.8 m trench depth. A powerful version of SMD’s burial tractor range, the vehicle is equipped with the latest advances in chain cutting technology, housing a 5.8-m jetting and cutting tool. In addition to the 2,400 hp of power available with the DBT2400, additional surface-located water pumps feed the jetting and cutting to enable this impressive trench depth.
SMD equipment business managing director Paul Davison said, “This 5.8-m jetting and cutting tool is the deepest cutting tool SMD has ever supplied.
“Van Oord approached us with their contract requirements, and we have worked in collaboration with them to develop a unique and cable-friendly solution.”
SMD Services’ customer training team delivered bespoke training courses to ensure Van Oord’s operational team was equipped with the necessary operating skills to get the best out of the machine. Alongside the trenching equipment, SMD Services supplied spares for use during trenching campaigns. SMD’s specialist team also accompanied Van Oord during vehicle testing, to offer support and assistance to the crew.
Subsea technology company Seatools delivered the umbilical winch for the massive trencher. The winch is distinguished by its ability to transfer exceptionally large amounts of power and data – a total of 1,800 kW of power at a voltage rating of 4,100 VAC.
The North Shields-based manufacturer also recently handed over a purpose-built pre-lay plough to marine service providers Boskalis for use on Ørsted’s Hornsea Two offshore windfarm.
The multi-functional pre-lay plough will be used by Ørsted’s contractor Boskalis to install 380 km of export cables which will ultimately connect Hornsea Two’s offshore substation to the site’s onshore substation in Killingholme, Lincolnshire.
The pre-lay plough, named Megalodon by Boskalis, benefits from features such as an active steering, multi modes, specialised share design and remote-control access.
The Megalodon can operate in a water depth of up to 500 m and is being used in collaboration with Boskalis’ offshore support vessel, Boka Falcon. Hornsea Two offshore work commenced in May, and Boskalis plans to complete the cable-laying campaigns for the project in six months.
Riviera is hosting a week of free to attend 45-minute webinars focused on offshore operations commencing 11 August. Register your interest now