Innovative Subsea Crane Ordered for RSV Conversion
Brazilian ship owning company CBO’s vessel CBO Manoella is currently being retrofitted from an offshore platform supply vessel (PSV) into a ROV Support Vessel (RSV).
As part of the conversion project, CBO has assigned Rolls-Royce to equip the vessel with a new patented hybrid dual draglink (DDC) subsea crane, marking the first installation of a subsea crane designed to be able to use either fiber or steel wire rope.
Marcelo Martins, CBO, Technical Director said, “This is one of two vessels CBO is now retrofitting from PSVs to RSVs, and we are very satisfied about the flexibility of the crane from Rolls-Royce. A hybrid solution, with use of either fiber or wire, makes the vessel better prepared to take on a larger variety of future subsea tasks.”
Rolls-Royce said the active heave compensated crane is designed for continuous operation in a tough and corrosive offshore environment with focus on efficient and safe load handling.
The crane to be installed on CBO Manoella is a hybrid dual draglink crane with a lifting capacity of up to 50 metric tons and an operating depth of up to 3,000 meters. It will be equipped with wire rope when it embarks on its first subsea assignment off the coast of Brazil. However the possibility of changing to fiber rope provides flexibility in a challenging market. Because of the low weight of the fiber rope, the vessel’s deck load capacity can be increased by approximately 100 metric tons. Another benefit of using a low weight fiber rope instead of steel wire is increased lifting capacity at large depths.
The cable tractions control unit (CTCU) forms the crane winch and is located at the crane’s main boom. This solution saves space compared to a solution where the CTCU unit is mounted below deck, and also makes it a better choice for retrofits. The horizontal elbow derrick movements provide Active Heave Compensation (AHC). This significantly reduces wear and build-up of heat in the lifting line compared to when the AHC is part of the winch.
CBO Manoella has 76.7m overall length, a beam of 17m, and a gross tonnage of 2,668 metric tons. It has a Rolls-Royce UT 715 L design and first went into service in 2009. It was then number two in a series of nine UT 715 L-designs ordered by CBO. Today the vessel is part of CBO’s current fleet of in total 27 offshore vessels, of which 14 are UT-designs from Rolls-Royce.
Rolls-Royce’s delivery is set to take place in Q3 this year, comprising a complete DDC crane system including the CTCU, cabin and control system.
