Once delivered, Royal IHC’s Seven Vega will become Subsea 7’s first vessel equipped with a pipelay system
Scheduled for delivery from Royal IHC in early 2020, Seven Vega is the ninth to be designed, engineered and built by the Dutch shipyard for Sutton, UK-based Subsea 7. However, it is the first Subsea 7 vessel to be equipped with a pipelay system, also designed, engineered and built by Royal IHC.
Royal IHC is aiming to provide a relatively compact vessel, facilitated by the positioning of the three enginerooms and main reel, efficient use of the vessel’s superstructure and a low-profile pipelay ramp. The vessel will measure 149.2 m, have a breadth of 33 m, a draught of 8.3 m and dwt of 10,900.
Dynamic positioning (DP) capability is provided by Kongsberg, giving the vessel a class of DP3. This includes three differential GPS units, two high-precision acoustic positioning units, a taut-wire sensor, a hydroacoustic position reference system and a RADius relative position reference system.
It will have six engines in total, with three 3,500 kW units and three 4,000 kW units. Propulsion comes in the form of a package from Wärtsilä comprising three 3,200 kW stern-mounted azimuth thrusters, two 2,400 kW retractable bow-mounted azimuth thrusters and two 2,200 kW bow-mounted tunnel thrusters. Hyundai will provide the main diesel generator sets. The vessel will have a service speed of approximately 13 knots and a maximum bollard pull of 100 tonnes in DP3 failure mode.
The vessel will be fitted with two permanently installed side-launching work-class Perry XLX-EVO ROV systems, from Houston, Texas-based Forum energy Technologies, rated to operate in depths down to 3,000 m. The XLX-EVO is a fully integrated survey system capable of interfacing with all modern survey equipment, including sub-bottom profilers and multibeam sonars.
Rotterdam-based Croonwolter&dros and Sliedrecht-based Bakker Sliedrecht have been contracted to produce and fit the integrated electrical and nautical systems for the vessel, with Croonwolter&dros focusing on the low-voltage installations and Bakker Sliedrecht focusing on high-voltage installations and drive systems. The scope of the contract includes three 6.6 kv main switchboards, three 440 v auxiliary switchboards, seven water-cooled electrical drive systems for the thruster system, motors for the thruster system, DP design in accordance with Lloyds AAA notation requirements, alarm, monitoring and control systems, navigation and communication equipment, main power supply for all mission equipment, complete lighting installation and complete cable installation and connection.
This contract marks the ninth occasion on which Subsea 7 has opted to use Croonwolter&dros and Bakker Sliedricht for electrical installations, with all of the vessels having been designed and built by Royal IHC.
Main lifting capacity comes from a 250-tonne active-heave compensated crane, to be manufactured and installed by Huisman. Alongside this, the vessel will be fitted with an active-heave compensated auxiliary crane with a 50-tonne capacity, another auxiliary crane with a 15-tonne capacity and a ramp-top crane with a 20-tonne capacity. All auxiliary cranes, as well as the main crane’s whipline, are certified for man-riding operations.
Due to the positioning of the enginerooms, main reel and superstructure space usage, the vessel has a large main deck of approximately 800 m2, with a strength of 10 tonnes per m2.
Storage tanks can hold 2,900 m3 of marine gasoil, 725 m3 of potable water, 3,900 m3 of ballast water, 1,680 m3 of fresh water and 1,200 m3 of heeling/stabiliser tank capacity.
To carry out pipelaying duties, the vessel will be fitted with two reels. The main reel has a maximum storage capacity of 5,600 tonnes and will be capable of stowing products ranging from 4” to 20” in diameter. The secondary reel has a storage capacity of 1,600 tonnes. The upper tensioner has a 162-tonne capacity, the lower tensioner a 318-tonne capacity and the back tension is 130 tonnes, making for a total maximum dynamic top tension of 600 tonnes.
The vessel is also fitted with two 325-tonne abandonment and recovery winches, which can be used in a combined mode to recover a catenary weight of 650 tonnes. Other features include a ramp angle of 45-95°, capability for piggyback direct electric heating and rigid systems, flexible pipe top tension of 210 tonnes, a 21 m aligner diameter, a 75-tonne spooling-on tensioner, a twin-level workstation and 14” by 18” pipe-in-pipe straightening capability. The system will also be able to deploy pipeline end terminals measuring 5 m by 5 m by 10 m.
The reel-lay system is designed to focus on operational efficiency, flexibility and crew safety. The twin-tensioner pipelay ramp’s tilt allows installation to range from shallow waters to depths of up to 3,000 m. The multi-level workstation makes for more efficient operations in and around the firing line, and the auxiliary reel, which is fixed into a recess in the main deck, allows for payload flexibility.
Provision is made to accommodate 120 people, with four suites, 42 single cabins and 37 double cabins. Seven Vega’s helideck will be approved for usage by Airbus Helicopters’ H225 Super Puma and Sikorsky’s S61N, S76 and S92 helicopters. It will incorporate a Kongsberg HMS 100 helideck monitoring system, which analyses helideck motion during landing operations to increase safety in rough weather, tracking helideck attitude and vertical velocity, wind speed and direction, air temperature and barometric pressure.
Lloyd’s Register has been chosen as the vessel’s classification society and has awarded notations including crew accommodation comfort of CAC(3), Winterisation H and D, covering materials for hull construction and direct design of -30, and an Ice Class of 1D. It also holds the ECO notation, meaning that its construction and operation exceed current statutory environmental requirements in the maritime sector.
It will be compliant with IMO’s Code of Safety for Special Purpose Ships, which recommends design criteria, construction standards and other safety measures for so-called special purpose vessels, ie vessels that carry more than 12 persons in addition to the crew, that are not passenger craft, and exceed 500 gt.
The signing of the Letter of Intent for the vessel was announced in September 2017, with Royal IHC the likely builder. At the time, Subsea 7 chief executive Jean Cahuzac explained the decision to order the new vessel saying: “We are committed to having the right fleet size and specification to meet the needs of our clients. We achieve this through a combination of owned high-specification vessels and leased vessels, having strict regard to capital discipline. We have removed three owned vessels from our fleet during the last two years and will continue to actively manage our fleet composition.
“The expected gradual recovery of market activity and application of new cost-effective technology supports this investment decision, which will enable Subsea 7 to participate in new prospects that are already visible in the market.”
New standards in offshore pipelay
Royal IHC was formally contracted to design, engineer and construct the vessel in October 2017, with Royal IHC chief executive Dave Vander Heyde saying at the time: “We are very proud of the confidence that Subsea 7 has placed in IHC. Our integrated approach to vessel design will give Subsea 7 an industry-leading asset that sets a new standard in offshore pipelay. Based on the ratio between top pipe tension and payload to displacement, this will be one of the most cost-effective vessels to enter the market.”
In February 2018 it was announced model testing for resistance and propulsion, along with seakeeping performance validation, had been successfully completed at the Maritime Research Institute Netherlands
In July this year, the keel-laying ceremony took place at Royal IHC’s Krimpen aan den Ijssel yard in the Netherlands. Speaking at the ceremony, Subsea 7 vice president of strategy and commercial Stuart Fitzgerald said: “The vessel marks an important investment for the future. When delivered, Seven Vega will be one of the most capable and cost-effective reel-lay vessels in the market and a global enabler for Subsea 7. It has been designed to deliver economical technologies that address the growing market trend towards longer tie-back developments.
“The vessel’s cutting-edge pipelay system focuses on crew safety, operational efficiency and flexibility. This system will be capable of installing complex rigid flowlines, including pipe-in-pipe systems and electrically heat-traced flowlines in water depths up to 3000 m.”
The first three sections of the vessel to be built will make up the lowest part of the main reel recess and one of the three enginerooms.
At the same time, the new vessel’s name, Seven Vega, was announced. The name was provided by a Subsea 7 employee, who competed with 1,700 of his colleagues for the honour. Mr Fitzgerald said: “It was important for us to involve our employees in the journey of our newbuild vessel.
“We chose Seven Vega because Vega is one of the brightest stars in the northern sky and will become the North Star in the future. We look forward to welcoming the winner of the competition to the naming ceremony and to Seven Vega joining the fleet in the first half of 2020.”
Mr Vander Heyde added: “We are proud to have reached this important milestone for the fully integrated reel-lay vessel. We think the name suits this prestigious vessel and are looking forward to progressing the building process and seeing Seven Vega taking shape on the slipway.”