DUTCH-BUILT PIPELAYER RAISES THE BAR

Built in the Netherlands by Royal IHC, and incorporating innovative features devised in cooperation with the shipowner, the diesel-electric Seven Vega embraces flowline technologies that address the growing offshore market trend towards longer and more complex tie-back developments.

The arrangements provide a high degree of operational flexibility, including the handling of sophisticated pipe-in-pipe, piggyback and electrically heat-traced flowline systems, risers, umbilicals and other structures. The vessel is equipped with two reels and a twin-tensioner pipelay ramp which tilts so as to place pipe at depths ranging from shallow areas up to 3,000m.

The two reels afford a total storage capacity of 7,200t. The main reel can hold 5,600t, stowing product from four- to 20-inch diameter, while the secondary reel, recessed into the main deck, can carry 1,600t. The maximum dynamic top tension of the reel-lay system is 600t. Seven Vega is fitted with multiple cranes, the two largest of which offer respective lifting capacities of 250t and 50t, and also permanently boards two side-launching work-class remote operated vehicle (ROV) systems fitted amidships. The main cranes and ROVs are rated for deployments in depths as great as 3,000m.

Given the considerable amount of equipment and machinery above and below deck, the ship is of relatively compact main dimensions. This has been facilitated by the positioning of the three engine rooms and the main reel, efficient use of the forward superstructure, and the low-profile pipelay tower. Adept use of space has resulted in a large, aft working deck, while the optimised mass distribution has minimised the ballast water requirement.

Given the nature of the operational demands on such a vessel, whereby pipe has to be laid and equipment placed with the utmost precision and safety, while adhering to project schedules in adverse sea and wind conditions, Seven Vega hosts an extensive array of propulsors and prime movers to efficiently serve the wide-ranging load profile.

Seven propulsion and manoeuvring thrusters confer a DP3 level of dynamic positioning. All other shipboard consumers are powered by six main generator sets based on Hyundai HiMSEN medium-speed engines, comprising three aggregates of 3,500kW and three of 4,000kW.

Dutch companies Bakker Sliedrecht and Croonwolter&dros were tasked with responsibility for the newbuild’s complete electrical installation, the former focusing on the high-voltage installations and drives, and the latter on the low-voltage side. Key elements of the contract package were the water-cooled drive systems for the seven thrusters, the electric motors for the three 3,200kW main propulsion stern azimuthing thrusters, two 2,400kW retractable bow azimuthing units, and two 2,200kW bow tunnel thrusters, three 6.6kV main switchboards and three 440V auxiliary boards. The DP system was supplied by Kongsberg Maritime.

The all-electric main Huisman crane allows lift parameters to be adjusted promptly without having to manually adapt the active heave compensation system. Through a lower component count, reduced maintenance and energy consumption is foreseen.

Seven Vega is fitted with accommodation for up to 120 personnel and has the Isle of Man as the flag state authority. Launched from the group’s Krimpen aan den IJssel yard near Rotterdam, she is the ninth vessel delivered to date by Royal IHC to Luxembourg-registered, London-headquartered Subsea 7. The company reported on 12 November that the ship had entered operations and was loading pipe for her first project.

PRINCIPAL PARTICULARS – Seven Vega