Rescue and salvage ships render assistance to disabled ships, provide towing, salvage, diving, firefighting and heavy lift capabilities.
The mission of the rescue and salvage ships is fourfold: to debeach stranded vessels, heavy lift capability from ocean depths, towing of other vessels, and crewed diving operations. For rescue missions, these ships are equipped with fire monitors forward and amidships which can deliver either firefighting foam or sea water. The salvage holds of these ships are outfitted with portable equipment to provide assistance to other vessels in dewatering, patching, supply of electrical power and other essential service required to return a disabled ship to an operating condition.
The Navy has responsibility for salvaging U.S. government-owned ships and, when it is in the best interests of the United States, privately owned vessels as well. The rugged construction of these steel-hulled ships, combined with speed and endurance, make these rescue and salvage ships well-suited for rescue/salvage operations of Navy and commercial shipping throughout the world. The versatility of this class of ship enables the U.S. Navy to render assistance to those in peril on the high seas.
Capabilities
Grapple is designed to perform combat salvage, lifting, towing, off-ship firefighting, crewed diving operations, and emergency repairs to stranded or disabled vessels.[1][2][3]
Salvage of disabled and stranded vessels
Disabled or stranded ships might require various types of assistance before retraction or towing can be attempted. In her 21,000 cubic feet (590m3) salvage hold, Grapple carries transportable cutting and welding equipment, hydraulic and electric power sources, and de-watering gear. Grapple also has salvage and machine shops, and hull repair materials to effect temporary hull repairs on stranded or otherwise damaged ships.[1][2]
Retraction of stranded vessels
Stranded vessels can be retracted from a beach or reef by the use of Grapple's towing machine and propulsion. Additional retraction force can be applied to a stranded vessel through the use of up to six legs of beach gear, consisting of 6,000-pound (2,700kg) STATO anchors, wire rope, chain, and salvage buoys. In a typical configuration, two legs of beach gear are rigged on board Grapple, and up to four legs of beach are rigged to the stranded vessel.[4]
In addition to the standard legs of beach gear, Grapple carries 4 spring buoys. The spring buoys are carried beneath the port and starboard bridge wings. Each spring buoy weighs approximately 3,100 pounds (1,400kg), is 10 feet (3.0m) long and 6 feet (1.8m) in diameter, provides a net buoyancy of 7½ tons, and can withstand 125 tons of pull-through force.[4] The spring buoys are used with beach gear legs rigged from a stranded vessel when deep water is found seaward of the stranded vessel.
Towing
Grapple's propulsion machinery provides a bollard pull (towing force at zero speed and full power) of 68 tons.[5][6]
The centerpiece of Grapple's towing capability is an Almon A. Johnson Series 322 double-drum automatic towing machine. Each drum carries 3,000 feet (910m) of 2.25-inch-diameter (57mm) drawn galvanized, 6×37 right-hand lay, wire-rope towing hawsers, with closed zinc-poured sockets on the bitter end. The towing machine uses a system to automatically pay in and pay out the towing howser to maintain a constant strain.[5][6]
The automatic towing machine also includes a Series 400 traction winch that can be used with synthetic line towing hawsers up to 14inches in circumference. The traction winch has automatic payout but only manual recovery.[5][6]
The Grapple's caprail is curved to fairlead and prevent chafing of the towing hawser. It includes two vertical stern rollers to tend the towing hawser directly aft and two Norman pin rollers to prevent the towing hawser from sweeping forward of the beam at the point of tow. The stern rollers and Norman pins are raised hydraulically and can withstand a lateral force of 50,000 pounds (23,000kg) at mid barrel.[5]
Two tow bows provide a safe working area on the fantail during towing operations.[5]
Grapple has several diving systems to support different types of operations. Divers descend to diving depth on a diving stage that is lowered by one of two powered davits.
The diving locker is equipped with a double-lock hyperbaric chamber for recompression after deep dives or for the treatment of divers suffering from decompression sickness.[8]
The MK21 MOD1 diving system supports crewed diving to depths of 190 feet (58m) on surface-supplied air. A fly-away mixed gas system can be used to enable the support of diving to a maximum depth of 300 feet (91m).[8]
The MK20 MOD0 diving system allows-surface supplied diving to a depth of 60 feet (18m) with lighter equipment.[8]
Grapple carries SCUBA equipment for dives that require greater mobility than is possible in tethered diving.[8]
Recovery of submerged objects
In addition to her two main ground tackle anchors (6,000-pound (2,700kg) Navy standard stockless or 8,000-pound (3,600kg) balanced-fluke anchors) Grapple can use equipment associated with her beach gear to lay a multi-point open water moor to station herself for diving and ROV operations.[2]
A typical four-point-moor consists of an X pattern with four Stato Anchors at the outside corners and Grapple at the center, made fast to a spring buoy for the close end of each mooring leg with synthetic mooring lines. Using her capstans, Grapple can shorten or lengthen the mooring line for each leg and change her position within the moor.[9]
Grapple has a 7.5-ton-capacity boom on her forward kingpost and a 40-ton-capacity boom on her aft kingpost.[6][8][10]
Heavy lift
Grapple has heavy lift system that consists of large bow and stern rollers, deck machinery, and tackle. The rollers serve as low-friction fairlead for the wire rope or chain used for the lift. The tackle and deck machinery provide up to 75 tons of hauling for each lift. The two bow rollers can be used together with linear hydraulic pullers to achieve a dynamic lift of 150 tons. The stern rollers can be used with the automatic towing machine to provide a dynamic lift of 150 tons. All four rollers can be used together for a dynamic lift of 300 tons[8] or a static tidal lift of 350 tons.[11]
Grapple also has two auxiliary bow rollers, which can support a 75-ton lift when used together.[8]
Off-ship fire-fighting
Grapple has three manually operated fire monitors, one on the forward signal bridge, one on the aft signal bridge, and one on the forecastle, that can deliver up to 1,000 gallons per minute of seawater or aqueous film forming foam (AFFF)[8] When originally built, Grapple had a fourth remotely controlled fire monitor mounted on her forward kingpost,[1] but this was later removed. Grapple has a 3,600 gallon foam tank.[6]
Emergency ship salvage material
In addition to the equipment carried by Grapple, the US Navy Supervisor of Salvage maintains a stock of additional emergency fly-away salvage equipment that can be deployed aboard the salvage ships to support a wide variety of rescue and salvage operations.[12][13]
In September 1988, LST-1190 USS Boulder ran aground on a shoal in a Norwegian fjord during Exercise: Teamwork. The Grapple, along with two Norwegian tugs, removed Boulder from the shoal.[14] As of February 2019, Grapple is berthed behind Boulder and three Charleston-class vessels.
Adriatic Sea (F-16 recovery)
The Grapple also helped to recover an F-16C which had crashed in the Adriatic Sea in 2013, killing its pilot.[15]
Botwood Harbor, Newfoundland, Canada
In July 2014, Grapple was in Newfoundland's Botwood Harbor for the body recovery from a 1940s plane wreck.[16]
Corsica (Calvi)
In October 2012, Grapple supported research operation diving on a sea landing B-17 in WWII.[16]
Atlantic Ocean, 100km (62 miles) south of Nantucket
In January 2010, Grapple assisted in the search and recovery of aircraft fuselage pieces and "black-box" flight recorders following the crash of Ethiopian Airlines Flight 409.[19]
The former USS Grapple sits in mothballs at the Philadelphia Navy Yard - February 16, 2019.
Related Research Articles
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↑ "US Navy Salvor's Handbook"(PDF). Supervisor of Salvage and Diving. 31 December 2003. Archived from the original(PDF) on 3 March 2016. Retrieved 11 February 2019.
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