By adding walk-to-work, cable-laying and heavy-lift solutions, shipowners can breathe new life into existing vessels
Not surprisingly, newbuilding activity in the OSV sector is non-existent, but several owners are active converting existing tonnage for specialised opportunities in the offshore energy sector.
A 20-year-old former drillship, for example, will find a new life in the offshore wind sector, following its conversion to offshore crane vessel at Drydocks World Dubai.
Owned by Dutch shipowner Royal Boskalis Westminster, the ex-Yan and ex-GSF Jack Ryan, previously owned by drilling contractor Transocean, will be deployed to the Taiwanese offshore windfarm market in 2021.
To be named Bokalift 2, the vessel will have its hull and deck modified to transport and install foundations and piles. To accomplish the conversion, Drydocks World Dubai will fabricate and install 9,000 tonnes of steel blocks on both sides of the vessel, increasing its stability. Along with the installation of a new work deck, a 4,000-tonne Huisman offshore mast crane will be installed on the vessel in 2021. This revolving crane will be capable of lifting structures more than 100 m above deck. A fly jib allows smaller components to be lifted to a height of 125 m above deck.
The configuration of the hoisting tackle is such that the crane is capable of lifting large jackets and of upending long monopiles from a horizontal to vertical position. The crane is also fitted with auxiliary systems to help install tall structures while the vessel is subject to wave-induced motions. Huisman said its mast cranes have a small footprint and no tail swing, which leaves maximum space on the deck of the vessel for payload. With its ability to lift structures more than 100 m high, Huisman’s crane will make Bokalift 2 a flexible asset, able to install current and future offshore wind turbine foundations and undertake work in the offshore oil and gas, decommissioning and salvage industries.
Boskalis chief executive Peter Berdowski said: “The huge deck space combined with the large crane make the Bokalift 2 an extremely versatile asset and valuable addition to the Boskalis fleet. We look forward to putting this unique crane vessel to work on its maiden offshore wind project in Taiwan.”
Bokalift 2 will be deployed for the first time at the Changfang and Xidao offshore wind farm (CFXD OWF) project in Taiwan, owned by Copenhagen Infrastructure Partners (CIP) and two Taiwanese life insurance companies. The project includes the transportation and installation of 62 three-legged jacket foundations and the accompanying 186 pin piles.
Drydocks World chief executive Capt. Rado Antolovic said all the production work for the conversion was being carried out with strict Covid-19 precautionary safety measures.
The shipyard said it will carry out the conversion work as per Bureau Veritas class rules, including those for detailed engineering, supplying steel, piping and electrical bulk material, as well as constructing and installing client-issued equipment.
Four retractable steerable thrusters, thruster controls and two tunnel thrusters are being supplied by Wärtsilä for the conversion.
Bakker Sliedrecht is responsible for the engineering, production, supply, installation, testing and commissioning of all electrical systems on the vessel. The company said the high voltage installations and the drive systems for the main thrusters will be renewed, upgraded or retrofitted. New drive systems for the bow thrusters and anti-heeling system, transformers and new switchboards will be supplied and the ship’s dynamic positioning, power management and vessel management systems will be updated.
Once completed, Bokalift 2 will be operated by BoWei Offshore, a joint venture between Boskalis and Hwa Chi construction.
Conversion to an ERRV
Dutch shipyard Royal Niestern Sander has signed a contract with Dixstone Holdings Ltd to convert a platform supply vessel (PSV) into a walk-to-work (W2W) emergency response and rescue vessel (ERRV).
Built at the Wuhu shipyard in China, the PSV SK Line 728 arrived at Niestern Sander’s repair yard at the end of May. The conversion will take around nine months, with an expected delivery in early 2021.
Armed with its experience from converting the newbuilds Kroonborg and Kasteelborg into W2W vessels in 2018, Niestern Sander will employ a similar strategy for the Wärtsilä Design vessel. In order to comply with the ERRV-B standards and the intended future operations, the vessel will undergo a significant modification. Part of the conversion scope includes adding an extra bow thruster, daughter craft and motion-compensated gangway. Additionally, a large accommodation block with offices, treatment room, storage space and cabins will be constructed on the deck of the vessel.
Following its conversion, the vessel will go on long-term charter as a W2W vessel to provide maintenance services for the gas platforms in the southern North Sea on the UK continental shelf. The vessel will support a large independent European oil and gas operator to maintain the performance of the platforms and optimise the maintenance and de-complexing activities, leading to a further reduction of the operational expenditure whilst increasing performance and safety. The lower cost means that the field life of these platforms can be extended. The vessel will accommodate around 40 of the charterer’s personnel onboard, to provide the maintenance services.
Modified for seismic operations
Privately-held Dutch OSV owner Rederij Groen BV has taken delivery Mariska G, following its conversion in Singapore for offshore seismic survey activities.
Built by China’s Wuhu Xinlian Shipbuilding to Bureau Veritas class, the six-year-old Mariska G has an overall length of 64 m, beam of 16 m, depth of 6.5 m and draught of 5.4 m.
Obtaining class approval for its engineering concept 10 days after the vessel arrived at the Tuas Yard in January, ST Engineering completed the conversion in two months, installing a new fuel oil tank and bunkering system and the one 8,000-m streamer and twin hose reels required for the seismic support function.
“The removal of existing cement tanks, fabrication and conversion of various tanks into fuel oil tanks, as well as integration of the fuel oil system interface with the ship system were among the complex engineering works involved in this contract,” said ST Engineering Marine vessel manager Dirk Klok, who was responsible for Mariska G’s redelivery,
“To achieve the modification works within the tight timeline, we anticipated the challenges, had the right resources on standby and were well prepared. It was all hands’ on deck for our crew,” said Mr Klok.
Capable of operating as a seismic support research vessel, Mariska G was redelivered to Rederij Groen in March.
Critical SPHL upgrade
In May, ST Engineering announced the completion of modifications to Subsea 7’s construction flex-lay and diving vessel Seven Eagle at its Tuas yard. The yard installed a self-propelled hyperbaric lifeboat (SPHL), transferring the craft from Seven Eagle’s sister vessel, Seven Osprey.
The transfer was far from straightforward, due to the differences between the two vessels in terms of weight, geometry, and the manway entry location of the SPHL. ST Engineering had to make modifications to the hull to allow for the longer SPHL, deck stiffening for the foundations, and re-running of hydraulic pipes and electrical cables.
Under DNVGL class, the 138-m Seven Eagle has an integrated saturation dive system that can be deployed through two moon pools with a depth rating of 230 m. The SPHL modification was a critical modification for Subsea 7, replacing an obsolete 16-man SPHL to conform with the latest industry standards.
Hyperbaric rescue of divers in saturation is a mandatory requirement for diving operations. In the event of any incident that endangers the vessel, the ship crew will abandon the ship by conventional lifeboats, while the divers will be extracted and rescued with the use of SPHL, keeping them in hyperbaric condition.
“The scope of work was challenging, the alignment of the SPHL trunk was identified early on the most critical activity,” said Subsea Seven vessel superintendent Michael Campbell. “The LARS upgrade was equally challenging, each 8-tonne winch had to be expertly chain blocked into a tight area and the guide winches fitted into an impossibly tight area,” he added.