Kleven Verft in Ulsteinvik and Rolls-Royce have both been busy on an interesting and important project for Maersk Supply Service, which ordered six anchor handling tug supply (AHTS) vessels from the Norwegian shipbuilder at the end of 2014, just as the downturn in the offshore market began. Maersk has kept faith and not retracted the order, and the vessels will be delivered during 2017 and 2018.
“In our newbuilding project with Kleven, we have carefully designed the vessel for maximum flexibility and lowest possible operational costs. Customer feed-back is positive and we believe that the vessels will play a role in enabling the industry to derive the needed gains in efficiency,” says chief commercial officer of Maersk Supply Service, Søren Karas.
One example of the company’s approach to the design of these AHTSs is the installation of a highly fuel efficient and flexible hybrid propulsion system with fixed pitch on all side thrusters. This provides a high degree of reliability and back-up, good fuel economy, low emissions and excellent station-keeping.
The Starfish series is based on the SALT 200 AHTS from Salt Ship Design and is being constructed at Kleven’s two yards in Norway, Kleven Verft and Myklebust Verft. The first two vessels, as yet unnamed, are due to be delivered in the first quarter of 2017 and the remaining four at regular intervals through and into early 2018.
The Starfish AHTS measures 95m length overall with a moulded breadth of 25m and has a deadweight of 4,500 tonnes. Each vessel will be fitted with total propulsion power of 17,665kW, giving the vessels a service speed of 14 knots with a maximum speed of 16 knots, and a bollard pull of 230 tonnes. The vessels will have two controllable pitch (CP) propellers with an output of 7,340kW each, two tunnel thrusters aft that have a power output of 1,200kW each, and three tunnel thrusters forward that each have a power output of 1,200kW.
The vessels will also be fitted with an extensive array of Rolls-Royce deck machinery, which includes the company’s next generation anchor recovery frame (ARF) that has been designed in co-operation with Maersk to optimise vessel safety and efficiency. Runar Hjelle, area sales manager for Rolls-Royce, says: “The new system is designed to reduce the loads generated when anchors are lifted from sea to deck, and lowered from the deck into the sea. And when not in use, this innovative recovery frame can be stowed in a deck recess hidden by a mechanically operated hatch cover, providing a much safer working deck environment for ships’ crews.”
Unlike existing anchor handling frames, which have a 90 degree operating angle, the Rolls-Royce ARF can be operated at a 126-degree angle to the deck by way of two hydraulic cylinders and a free-rotating roller with a 1,680mm diameter. The Rolls-Royce ARF is capable of operation in temperatures ranging from -20°C to -45°C, and the 8,840mm wide, 7,990mm high recovery frame has a nominal towline tension capacity of 200 tonnes with a lateral force of 50 tonnes.
The order for equipment placed with Rolls-Royce for these AHTSs is valued at £54 million (US$73 million). It will also see the company equip the vessels with a triple drum main anchor handling winch with a pull capacity of 500 tonnes, two secondary winches, cargo securing winches and other auxiliary winches, and a dry bulk cargo system. The scope of supply from Rolls-Royce also includes rudders and steering gear for all six vessels.
Danfoss Semco is another company that has been involved with fitting out the latest Maersk AHTS vessels, supplying the fixed installation fire-fighting systems. These comprise a high pressure CO2 system for the engineroom, total flooding alongside, and a SEM-SAFE high pressure water mist system.
The Starfish vessels, the first of which was launched at Kleven in June this year, are designed to provide Maersk’s customers with a reliable and efficient service in anchor handling and towing. They can also carry goods to and from offshore facilities and perform oil recovery operations. As well as the ARF and hybrid propulsion system there are several other innovative features on the Starfish vessels, including a deck handling gantry crane with remotely operated clamping hand, and a high degree of insulation on the main engine and the connected systems to prevent an engineroom fire.
“The Starfish vessels are unlike any other anchor handlers currently on the market. This is a premium asset that is second to none in terms of operational reliability, onboard safety and comfort and client offerings. These vessels have been developed based on how best to provide value to our customers,” adds Peter Kragh Jacobsen, head of newbuildings at Maersk Supply Service.
Another innovative AHTS design soon to be commissioned is ALP Striker, the first of four Ulstein Design & Solutions SX157 long-distance towing and anchor handling vessels being built by Niigata Shipbuilding & Repair in Japan.
ALP Striker is the lead ship in the so-called ALP Future class, which have a fuel capacity of 3,400m3 of intermediate fuel oil or marine gas oil, sufficient for non-stop transatlantic and transpacific towing operations without the need for bunker fuel calls. These 88.90m long, 4,250 dwt long-distance towing vessels, which will enter the fleet of ALP Maritime Services, a division of the Teekay group, have a 306 tonnes bollard pull capacity, a service speed of 13 knots, a top speed of 19 knots and a cargo deck area of 550m2, with a deck load capacity of 2,400 tonnes. Additionally, ALP Striker and its three sisters are equipped with DP2 dynamic positioning capability.
The investment in this new AHTS ship class reflects a shift in direction for ALP, which has its roots in the former Fairmount Marine business and was acquired by Teekay Offshore Partners in 2014. The company is now focusing more on long-haul business, moving away from shorter-distance offshore markets. It has worked closely with the vessel designer, Ulstein, to ensure the vessels are optimised for the markets they will now be serving.
Gerrit-Jan Fidder, assistant sales and marketing manager for ALP Maritime Services, explains: “All the tanks on board are dedicated to fuel. So these ships will have a maximum service capability of 100 days without having to refuel, or 50 days at full power.”
ALP Striker is powered by four Caterpillar MaK 9M32C engines and also features Kongsberg’s K-Pos dynamic positioning, two 1,050kW Cat Propulsion stern thrusters and two 1,500kW bow thrusters, and three SL400-3T Rolls-Royce anchor handling/towing winches.
The ALP Future class ships feature the Ulstein X-Bow concept. Mr Fidder adds: “This will be a very efficient solution for the types of service these vessels will provide because of its wave piercing benefits, which will also reduce the strain on the tow cable.”
The ALP Future class will be used for a variety of tasks, the company expects, including oil rig work and floating production, storage and offloading (FPSO) and floating natural gas (FNLG) production unit tows. This could include both the installation of new facilities and the decommissioning of existing structures. The vessels’ DP2 and anchor handling capability will enable them to assist during the installation and hook-up phases for towed objects.
Equipment on board includes a stern roller, a three-drum winch with 400 tonnes hoisting capacity and chain lockers for a rig chain. ALP Striker and its sisters also have comfortable and spacious accommodation for 35 persons, reflecting the intention that these ships spend long periods at sea.
The ALP Future class is the largest single contract so far for Ulstein Design & Solutions. In developing the design, the company says it had to ensure that each vessel had sufficient bollard pull and operational reliability to handle even the heaviest tows over long distances, using just two vessels. Environmental protection and fuel efficiency were also important criteria. Ulstein points out that the vessels are classed to DNV GL Clean Design and Ice class 1B notations, which allow them to operate in areas that might be restricted to other craft.
After ALP Striker enters service three further vessels, ALP Defender, ALP Sweeper and ALP Keeper will be phased into service on delivery from Niigata shipyard. When all four are in operation, ALP Maritime Services will have a fleet of ten long-distance anchor handling and salvage vessels, with bollard pull capacities of between 192 and 306 tonnes, making it a major player in this niche towing segment.
© 2023 Riviera Maritime Media Ltd.