Technology | Vessels | USS Grasp/USS Grapple

USS Grapple and USS Grasp

The USS Grasp and USS Grapple are “sister” ships belonging to a new class of rescue and salvage vessels constructed for the U.S. Navy. As sister ships, they are similarly equipped and outfitted, with the only major difference between them being schedules and areas of deployment.

At 255 ft in length and displacing more than 3,200 tons, the USS Grasp and USS Grapple have a range of 6,900 nautical miles with a cruising speed of 8 knots. Each of these vessels carries a complement of six officers and 94 enlisted personnel. Both vessels are based in Little Creek, Virginia. The ships’ missions include heavy lifting from the ocean depths, manned diving operations, and the rescue and towing of other vessels.

Built for Big Jobs

Even under the calmest of ocean conditions, heavy-lifting operations from the depths are hazardous undertakings. These operations require extremely stable vessel platforms, specialized equipment and highly trained personnel. The ships’ heavy lifting system is comprised of both bow and stern rollers, deck machinery and tackle. The rollers provide a low-friction fairlead for the lift wires or chains. The deck machinery and tackle supply the required hauling force of up to 150 tons (75 tons to each lift wire). The two main bow rollers, or the two stern rollers, each carrying one-half of the load, are used to accomplish lifts of up to 150 tons. Bow and stern rollers can be used simultaneously to make a dynamic lift of up to 300 tons.

Advanced Diving

Salvage and rescue operations often require careful preparation by highly skilled crewmen working underwater for long periods of time. Both the Grasp and Grapple are outfitted to support a wide range of advanced diving procedures. For shallow underwater inspections, searches, and other tasks that require mobility, divers can be outfitted with standard scuba gear from the vessels’ well equipped dive lockers. For more complex underwater operations, MK12 and MK1 air-diving systems are used. These ships have the finest diver life-support air system in the fleet.

The MK 12 and MK 1 air diving systems enable Grasp and Grapple divers to make tethered descents to depths of 190 ft. While tethered diving provides less mobility than scuba, individuals can remain in contact with the diving control station on the vessel using special communications equipment in their helmets. Divers engaging in tethered diving procedures typically descend to depth on a diving stage lowered by one of the two diving davits. After completing their work, divers ascend on the diving platforms, stopping at predetermined depths so that they can “decompress” and avoid decompression sickness, better known as, “the bends”.

In the event that a diver succumbs to decompression sickness while acsending from depth, or for routine surface decompression, divers can be treated in the ships’ recompression chambers. These are specially designed to connect to a portable recompression chamber at their entry doors. Portable recompression chambers are used to transport divers to special medical facilities on shore in the event that their injuries are too severe to be treated on board.

Rescue Equipment

For rescue missions, each ship is equipped with fire monitors forward and amidships that can deliver up to 1,000 gal-per-min of either sea water or fire-extinguishing foam. In their 21,000-cubic ft salvage holds, the Grasp and Grapple carry transportable cutting and welding equipment, hydraulic and electric power sources, dewatering gear, salvage and machine shops, and repair materials to make temporary hull repairs on stranded or otherwise damaged ships. The ships also have a 7.5-ton capacity forward boom, and a 40-ton capacity aft boom, to offload disabled vessels, and handle heavy equipment during salvage operations. The Grasp and Grapple are capable of providing practically every essential service required to return a disabled ship to operating condition.

 

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