RSV retrofit includes world’s first hybrid subsea crane

Written by Nick Blenkey
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MAY 19, 2017 — A platform supply vessel that is currently being converted into a ROV Support Vessel (RSV) is to be equipped with a new patented Rolls-Royce dual draglink (DDC) subsea crane. This will be the first installation of a subsea crane designed to be able to use either fiber or steel wire rope.

The hybrid DDC subsea crane is be installed on the PSV CBO Manoella, which the first of two that Brazil’s Grupo CBO is now retrofitting for ROV support. currently being retrofitted from PSV into a ROV Support Vessel (RSV).

The active heave compensated crane is designed for continuous operation in a tough and corrosive offshore environment with a focus on efficient and safe load handling.

“We are very satisfied about the flexibility of the crane from Rolls-Royce,” says Grupo CBO Technical Director Marcelo Martins. “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 t and an operating depth of up to 3,000 m. It will be equipped with wire rope when it starts 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 tonnes. 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 76.7 m overall length, a beam of 17 m, and a gross tonnage of 2,668 tonnes. 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.

Gary Nutter, Rolls-Royce, Director, Products – Marine said: “We are very happy to be able to continue our close cooperation with CBO by retrofitting one of our previous designs. This project is a great example of how offshore ship owners are adapting to a new reality with the use of new technology.”

The delivery from Rolls-Royce will take place in Q3 this year. It comprises a complete DDC crane system including the CTCU, cabin and control system.

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