Illustration of the hybrid subsea crane. Image credit: Rolls-RoyceBrazilian ship owning company CBO has commissioned Rolls-Royce to equip an existing offshore platform supply vessel (PSV) with a new patented 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 will be installed on the vessel CBO Manoella, which is 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 focus on efficient and safe load handling.

The hybrid dual draglink crane has a lifting capacity of up to 50 tons and an operating depth of up to 3,000 m (9,843 ft.). It will be equipped with wire rope when it embarks on its first subsea assignment off the coast of Brazil. The potential to change to fiber rope provides flexibility in a challenging market. Because of the low weight of fiber rope, it translates into an increased vessel deck load capacity of 100 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), which reduces wear and build-up of heat in the lifting line compared to when the AHC is part of the winch.