Grab devices have been extensively used for commercial cargo salvage and sensitive military recovery projects throughout much of the past century Early grabs suffered from a lack of positional control and remote intelligence and thus were not very efficient The first truly controllable grab was developed in the early 1970s by the CIA in their partially successful attempt to recover a Russian ‘Golf’ class submarine This concept of a controllable Grab deployed from a modified drillship was commercialised In 1994 by Blue Water Recoveries (BWR) with development of a 3,000 metre rated Grab used to recover 18 tonnes of silver coins from the SS John Barry Although technically successful, it was soon apparent that this prototype GRAB 3000 would need to be Improved to be able to recover cargo at even higher rates of efficiency What was required was a blending of an extremely strong mechanical Grab that exerted forces of up to 200 tonnes with a very highly specified ROV control system and sensor suite Reliability and efficiency were the key design parameters of the new 6,000 metre rated Grab and bucket recovery system that was completed and sea-tested by BWR In late 1996 The new 150 horsepower GRAB 6000 was run from a unique fibre-optic cable and utilised twice the number of sensors found on most work-class ROVs Within weeks of it's deployment the GRAB 6000 was setting new standards In deep water salvage by recovering over 50 tonnes of cargo from a depth of 3,800 metres In a single lift
The first deep water grab system developed by Blue Water Recoveries (GRAB 3000 System) was instigated by the requirement to deploy a tool to the depth of the SS John Bnrry (2,600 metres), accurately position it on the wreck, and then remotely operate it to remove the deck and extract a specific cargo from within the cargo holds By deploying a tool from a drilling vessel on the end of the drill pipe the strength and control of the drilling system is harnessed to the tool and creates a powerful system with almost fingertip control This concept of operating tools other than drill bits from the end of a drill pipe is not new and has been utilised routinely since the very early days of oil exploration Most uses of this technique have been ‘down hole’ for carrying out a wide range of complex tasks but tools for use outside the hole have also been widely used
The design of the GRAB 3000 system evolved from previously used technology In particular the secret CIA operation to attempt to recover in one piece the Russian ‘Golf’ class submarine sunk off Hawaii in the 1960s This operation involved the design and build of the Glomar Challenger (now converted into a modern drillship) and the design of a special derrick and drill pipe system capable of lifting 7,000 tonnes
Deep water, which we consider as depths greater than approximately 1000 metres, excludes the effective use of explosives
