North Sea Giant Construction Umbilical Vessel

North Sea Giant is the longest offshore construction vessel in the world. She has an overall length of 156m. Image courtesy of Metalships & Docks.

North Sea Giant is a multipurpose offshore construction vessel designed to undertake both subsea construction and well intervention works. Image courtesy of Metalships & Docks.

The vessel is outfitted with two huge deck cranes. These were installed on the vessel at Kristiansand, the capital of Vest-Agder county, Norway. Image courtesy of Metalships & Docks.

A helicopter landing platform being fitted out on the vessel. The platform has a radius of 23m and is placed on the bow of the vessel. Image courtesy of Metalships & Docks.

A bridge measuring 500m² is built on the sixth deck. The vessel also features a moon pool which can be prepared for ROV operations. Image courtesy of Metalships & Docks.

North Sea Giant is equipped with state-of-the-art communication and navigation equipments. Image courtesy of Metalships & Docks.

North Sea Giant is an offshore construction vessel (OCV) designed for umbilical and mineral extraction related constructions in deep open sea conditions. With a length of 156m, she is one of the longest OCVs in the world. The vessel is owned by North Sea Shipping, a Norwegian family based shipping company.

The vessel has multiple utilities as she can conduct both subsea construction and well works, such as well intervention, module handling and coiled tubing intervention. Subsea construction activities that can be performed by the vessel include cable laying, pipe laying, dredging and remotely operated vehicle (ROV) support and survey.

The keel for the vessel was laid in August 2008. The vessel was launched in August 2009 and delivered in April 2011. Spanish shipyard Metalships & Docks constructed the vessel at its ship building facility in Vigo.

The hull was manufactured by RMK Shipyard located in Istanbul, Turkey. Frydenbø Marine Services was the owner’s site manager and also acted as broker for the project.

The vessel was designed by Norway-based ship design and engineering consulting company Sawicon. Heating, ventilation and air conditioning (HVAC)-plant was supplied by Novenco.

Design and features of one of the world’s longest OCVs

North Sea Giant is a DNV classified comfort class 3 and clean design multipurpose offshore vessel. DNV’s clean design notation intends to reduce and control operational emissions and discharges.

The vessel has high redundancy features based on low loss concept (LLC) diesel electric system. The vessel consumes less fuel compared to other vessels in her class due to her complete diesel power plant.

The structure of the vessel is highlighted by her 23m diameter helicopter landing platform placed on the bow and a 500m² bridge built on the sixth deck. The vessel’s working deck area, including 750m2 of closed area, is 2,950m². Load carrying capacity of the work deck is 10t/m2.

The vessel can store 2,000m³ of fuel oil, 1,000m³ of fresh water and 8,000m³ of ballast water. The vessel also features a 7.2m x 7.2m moon pool which can be equipped for ROV operations.

Each side of the vessel is fitted with a Frank Mohn (FRAMO) anti-heeling pumping system to minimise the impact of heeling, brought on by loading and unloading of cargoes. FRAMO anti-heeling system comprises a reversible propeller pump with electric motor, control system with inclinometer, level switches, butterfly valve and electric starter.

A passive stabilisation tank and an active anti-roll system are provided to give stability to the vessel during periodic roll movements induced by waves.

Dead weight of the vessel is 35,792t. Gross tonnage and net tonnage are 18,151t and 5,446t respectively.

Overall length of the vessel is 156m and length between perpendiculars is 144.06m. Moulded breadth, depth to main deck and maximum draft are 30m, 10.7m, and 7.5m respectively.

Accommodation facilities onboard North Sea Giant

A total of 120 people can be accommodated onboard the vessel. The cabin combination comprises 58 single cabins and 31 two-man cabins.

Onboard facilities of the vessel include two recreation rooms, a cinema hall, heli reception, online / offline room and conference room. There are eight offices, two ROV control rooms and two ROV garages.

Equipment for cargo and deck machinery

The vessel is equipped with two large offshore cranes. The first one is a Hydramarine knuckle boom crane with a maximum lifting capacity of 400t at 10m radius.

The second one is also a Hydramarine knuckle boom crane but with a maximum lifting capacity of 50t. The vessel also has a provision crane whose maximum lifting capacity is 2t.

The deck machinery includes two electro-hydraulic capstans and two electro-hydraulic anchor mooring winches.

Propulsion and manoeuvring systems of North Sea Shipping’s OCV

North Sea Giant is furnished with diesel electric propulsion systems comprised of six General Electric (GE) main engines, each producing 3,630kW at 900rpm, and six Leroy Somer main generators.

There is also an emergency engine of 600kW capacity.

The propulsion for the vessel is provided by three Voith Schneider main propellers of 3,800kW each.

The manoeuvring system comprises two Voith Schneider forward thrusters, each of 3,800kW, and a Rolls-Royce tunnel thruster of 2,000kW capacity.

The vessel is provided with Kongsberg’s DPC21 dynamic positioning (DP) Class-3 control system for automatic heading and positioning.