Rock Dumping Units

Huisman supplied custom-made rock dumping units and ROV systems for subsea pipeline protection purposes. For DeepRock's Seahorse, we delivered a complete rock dumping system in 1999. In 1994 we delivered a manipulator for fall pipe assembly and disassembly, an ROV and ROV control systems for fall pipe positioning and subsea surveying of pipelines for Tideway's Rollingstone. This included the detailed design of the steel structure, complete design of the overhead crane, ROV and all drive and control systems, manufacturing, commissioning and testing of all systems.

Rock Dumping Unit Rollingstone

The rock dumping unit for the Rollingstone consists of a 24mx16mx10m rectangular frame integrating pipe storage (300m, 500mm diameter, fall pipe and 100m, 1000mm diameter, fall pipe), overhead crane with pipe clamping tools for handling of pipe sections, hydraulically controlled tools for fall pipe assembly and disassembly, winch room (two fall pipe winches, 60t line pull each; three umbilical winches, 7.5t line pull each), hydraulic powerpack of approx. 300 kW, control room and a moveable ROV floor.

ROV

Positioning of the ROV is achieved by four hydraulic thrusters, powered by three electrohydraulic pressure compensated powerpacks of 100 kW each. The ROV has two retractable survey arms fitted with cameras, profilers and pipetrackers. The main frame of the ROV consists of a cylindrical structure, the total span with survey arms extended is approximately 11m.

The ROV is suspended by three umbilical wires installed on three mechanically coupled winch drums. A secondary, controlled hydraulic drive system with dedicated electronic control enables the Operator to run in active heave compensation mode. This enables stabilisation of the ROV at a distance of approx. 2m above the seabed, while the vessel undergoes a heave motion of more than 3m amplitude. The installation of our active heave compensation system extended the weather window and made rock dumping more accurate.

In 2002, the Seahorse was outfitted with a grab system to be used for the digging of "glory holes".

In 2008 we received two contracts for the design, build and commissioning of two new rock dumping systems. These systems are for Tideway BV and Royal Boskalis Westminster. The rock dumpers are both fast, highly automated and the world's first systems capable of accurately dumping stones up to 2,000m of water depth. The delivery of the systems is planned for the second half of 2010 and start of 2011.