Rolls-Royce has been contracted by Brazilian shipowner CBO to equip a platform supply vessel with the first example of its patented dual draglink subsea crane. The crane will be the first subsea crane designed to use either fibre or steel wire rope.
The hybrid dual draglink crane will be installed on CBO Manoella, which is currently being modified from a platform supply vessel (PSV) to a remotely operated vehicle (ROV) support vessel. 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.
Marcelo Martins, CBO’s technical director said: “This is one of two vessels CBO is now retrofitting in this way. We are very satisfied with the flexibility of the crane. A hybrid solution, with use of either fibre or wire, makes the vessel better prepared to take on a larger variety of future subsea tasks.”
The crane to be installed on CBO Manoella is a hybrid dual draglink crane with a lifting capacity of up to 50 tonnes and an operating depth of up to 3,000m. 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 fibre rope provides flexibility in a challenging market.
Because of the low weight of the fibre rope, the vessel’s deck load capacity can be increased by approximately 100 tonnes. Another benefit of using a low weight fibre rope instead of steel wire is increased lifting capacity at large depths.
The cable traction control unit (CTCU) forms the crane winch and is located at the 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. This significantly reduces wear and build-up of heat in the lifting line compared to when the active heave compensation system is part of the winch.
CBO Manoella is 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. Delivery of the crane from Rolls-Royce will take place in Q3 this year. The scope of supply includes a complete dual draglink crane system including the CTCU, cabin and control system.