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Cablelay vessel sets new standards for environmentally friendly operation

Fri 16 Jun 2017

Cablelay vessel sets new standards for environmentally friendly operation
NKT Victoria combines the ability to undertake dual HVDC and fibre optic cable-laying with deepwater installation capability and environmentally friendly operation

June 2017 saw NKT Victoria, an advanced, purpose-built, fuel-efficient and environmentally friendly cable-laying vessel, start work

Originally ordered by ABB, NKT Victoria was delivered to NKT following the acquisition by the company of ABB’s high voltage cable business in 2016 and completed its first cable-laying campaign on Scottish and Southern Electricity Networks’ £1.1 billion Caithness-Moray transmission project in early June.

NKT held a naming ceremony for the innovative vessel in April 2017 at its power cable plant in Karlskrona, Sweden. The vessel, which was designed by Salt Ship Design in Norway and built by Kleven shipyard, incorporates extensive experience with offshore cable installation and will lay high-voltage offshore cables with a particularly high level of precision using its DP3 dynamic positioning system and a remotely operated vehicle with underwater cameras and sonar.

Among the technically advanced features of the Salt 306 CLV design, said to be among the world’s most advanced and fuel-efficient, are the use of ABB Marine’s Onboard DC Grid, and the ability to use shore power whilst in port, further reducing the ship’s fuel consumption and emissions. The diesel-electric propulsion machinery employs six high-speed Caterpillar 3516 propulsion engines of 2 megawatts each, acting as gensets and providing power for three Azipod CZ980 thrusters of 1,900kW.

NKT Victoria is capable of simultaneous dual HVDC and fibre optic cable-laying and deepwater HVAC installation using a high capacity tensioner system. The two turntables installed on the vessel have a combined capacity of 9,000 tonnes and there is capacity for a 500 tonne of fibre optic tank below deck. To enable complete cable-lay capabilities ranging from the deepwater to the shore NKT Victoria is designed to be beachable in fully laden condition. The vessel is also fitted with a six-point mooring system. For work in ultra deepwater, the deck has been prepared to accommodate a vertical lay tower to enable sufficient high tension hold-back capabilities.

NKT Victoria was designed to operate with the highest possible level of safety, in full compliance with the most stringent requirements for a vessel of its type. The ship’s versatility is further strengthened by a fully integrated navigation and survey system that will enable NKT Victoria to operate in high sea states and conditions that would prevent most cablelay units for operating. The offshore market’s stringent safety requirements are met throughout the installation process thanks to sophisticated roll reduction technology that mitigates the effects of challenging sea conditions. Fire and flooding containment systems protect essential systems, ensuring ongoing operations are not compromised.

NKT Victoria can use shore power when available and the Onboard DC Grid will reduce fuel consumption significantly compared to other cable-laying vessels available on the market. The Onboard DC Grid system will increase the efficiency of the vessel by allowing the ship’s engines to work at variable speed, in combination with energy storage for peak shaving and enhanced dynamic performance, optimizing the energy consumption and reducing engine maintenance. Energy storage is also used for back-up for shore connection during cable loading, allowing the ship to be emission free during cable loading. Three Azipod C units will maximize the manoeuvrability of the ship and operate in DP3 mode when required. Azipod propulsion is significantly more fuel efficient than conventional propulsion systems.

UK-based MAATS Tech Limited managed the design, fabrication, delivery, installation and commissioning of the cablelay equipment to DNV GL certification. The specialist equipment included two four-track, 45 tonne tensioners, 7,000 tonne on deck carousel, 4,500 tonne underdeck carousel, loading arms, three three-tonne tensioners, chute assemblies and roller pathways, enabling the vessel to load or unload three products at synchronised speed. The equipment was mainly manufactured in the UK, with a large team of core suppliers and subcontractors. The company oversaw the development and delivery of the equipment to meet the schedule and also attended a series of trials before the ship was named.

Michael Hedegaard Lyng, president and CEO of NKT, said of NKT Victoria: “With this cable-laying vessel we are now among the very few AC/DC high-voltage offshore cable system providers to deliver complete turnkey solutions, and are well-positioned to continue taking an active part in the growing global market for offshore wind projects.”