‘Design for purpose’ makes for quicker, safer and more cost-effective transfers
The oil and gas industry could learn much from the ‘design for purpose’ approach to walk-to-work technology, a concept increasingly favoured by wind operators. There is clearly a lot to be gained from sharing knowledge, especially in areas such as the North Sea, where both oil and gas and wind projects will experience the same weather conditions and sea states.
In an editorial comment for sister publication Offshore Support Journal, Bibby Marine Services managing director Stephen Bolton considered what the oil and gas sector can learn from the wind sector when it comes to crew transfer. Mr Bolton noted that while the requirement for large accommodation vessels attached semi-permanently to platforms for major interventions remains, some recent applications have favoured smaller vessels for summer campaigns, where accommodation units may be unavailable.
The ‘design for purpose’ approach means that rather than simply taking existing vessels such as PSVs and fitting them with gangways for example, a vessel with an integrated gangway is designed from scratch, providing a ‘stepless solution’ whereby offshore structures can be accessed “without moving across steps or slopes of any significance”.
“This is done by the gangway being vertically height adjustable and attached or adjacent to an elevator integrated into the core of the vessel, providing direct access to the warehouse and technician areas,” said Mr Bolton.
As well as the welfare benefit to crews, this results in improved cycle times and allows for the transfer of heavy spare parts up to 400 kg using powered trollies, without the need for time-consuming crane operations.
Mr Bolton noted that if offshore accommodation modules can be closed by using such vessels, this could mean a step change in the cost-base of oil and gas, coupled with improvements in health and safety and reduced risk, due to less reliance on helicopters.
Bibby’s Wavemaster vessels, designed in collaboration with Dutch shipyard Damen, are examples of this design philosophy.
Wavemaster 1 was launched in 2017, while Wavemaster 2 is currently under construction at Damen Shipyards Galati in Romania. The newer vessel’s gangway package and crane will be supplied by Netherlands-based SMST.
“The gangway on the original vessel continues to perform well,” said Mr. Bolton in a press release, “but the technology has moved on and this new integrated system does away with the need for an independent lift tower.
“Now, the gangway hangs off the tower and matches where the lift is.”
These vessels are suitable for work on both windfarms and oil and gas projects, as Wavemaster 1 has demonstrated – its first charter was servicing windfarms off the East Coast of England, followed by a new charter for Total E&P Netherlands’ gas platforms in the southern North Sea.
New Damen Fast Crew Supplier design
In May Damen announced the introduction of a new Fast Crew Supplier model, the FCS 2710. A successor to the FCS 2610, introduced in 2011, the FCS 2710 is 26.8 m long, has a beam of 10.8 m and a depth of 4.3 m. With a maximum speed of 25 knots and a range of up to 1,200 nautical miles, the FCS 2710 can carry 26 passengers – double the capacity of its predecessor.
The vessel’s twin aluminium Sea Axe hull design results in lower water resistance, cutting fuel usage by 20% and generating less emissions. Propulsion options include conventional shaft, water jet, Volvo inboard performance system and Voith linear drives.
The new class is a metre taller and longer than its predecessor, which means that in addition to increased hull volume, the FCS 2710 can handle waves of up to 2 m in height, allowing it to operate in harsher weather conditions.
Designed with input from Vattenfall, Siemens and Eon, the FCS 2710 is designed with the offshore oil and gas, survey and renewables sectors in mind. The first vessel in the class is being constructed at Damen Shipyards Gorinchem and is targeted for delivery to Swansea-based High Speed Transfers Ltd (HSTL) in July 2017.
Gangway integration means safer crew transfer
Further collaboration from Damen has seen the integration of an Ampelmann L-type gangway system onto one of the Dutch shipbuilder’s FCS 5009 fast crew transfer vessels, Dijama. The vessel operates with LATC Marine on behalf of ExxonMobil offshore Nigeria.
Damen business development manager David Stibbe said: “It was the ability of all four stakeholders to work together effectively that has made this project a success.
“It represents a major step change away from the traditional swing roping transfer technique used in this area, and we hope it marks the start of a wider move towards safer and more efficient transfers in the region.”
As well as Dijama, an updated version of the L-type gangway is also to be installed on another FCS 5009 vessel, Chilosco, with a smaller footprint and higher working range.
The existing L-type gangway is suitable for vessels 30 m or longer, with or without dynamic positioning systems, and allows the continuous transfer of 50 people every five minutes in wave heights of up to 2 m.
Height-adjustable landing system
Meanwhile, Northumberland, UK-based Osbit has delivered a height-adjustable boat landing system for use with jack-up vessels to Gulf Marine Services UK Ltd.
The tower, which was fabricated on Tyneside and installed at the Port of Blyth, will provide crew access between crew transfer vessels and self-elevating support vessel (SESV) GMS Endeavour.
The system has five height settings, enabling it to be accessed in line with the position of the SESV across the full tidal range. The height of the system can be adjusted via GMS Endeavour's on-board crane, which has a capacity of 230 tonnes.
While the installation took place prior to GMS Endeavour’s deployment to the Hornsea Project One wind farm, the vessel is capable of supporting a range of well services as well as windfarm installation and maintenance projects.
Tried and trusted helicopters
Some operators are still sticking with an airborne approach to crew transfer, such as Abu Dhabi's state-owned Taqa, which has awarded helicopter operator Babcock a contract to transport workers to and from the Harding platform in the North Sea, 200 miles north of Aberdeen.
Babcock’s fleet of Sikorsky S92 helicopters will operate flights to the platform five times a week from Aberdeen heliport for a minimum of two years. Operation is expected to begin in early July and the company has acquired another aircraft specifically for the contract.