USS Thresher (SSN-593)
Encyclopedia : U : US : USS : USS Thresher (SSN-593)
 USS Thresher (SSN-593) | |
| Career |
|
|---|---|
| Ordered: | 15 January 1958 |
| Keel laid: | 28 May 1958 |
| Launched: | 9 July 1960 |
| Commissioned: | 3 August 1961 |
| Fate: | Lost during deep diving tests, 10 April 1963 |
| Stricken from US Navy's ship rolls: | 16 April 1963 |
| General Characteristics | |
| Displacement: | 3540 tons light, 3770 tons submerged |
| Length: | 279 ft (85 m) |
| Beam: | 32 ft (9.7 m) |
| Draft: | 26 ft (8.7 m) |
| Propulsion: | 1 Westinghouse S5W PWR, Westinghouse Geared Turbines 15,000 shp (11 MW) |
| Speed: | 20+ knots (37 km/h) |
| Complement: | 16 officers, 96 men |
| Armament: | Four 21-inch (533 mm) torpedo tubes amidships |
| Motto: | Vis Tacita (Silent Strength) |
She was named for a type of shark, which is harmless to man. It is easily recognizable because its tail is longer than the combined length of its body and head.
The contract to build the Thresher was awarded to Portsmouth Naval Shipyard on 15 January 1958, and her keel was laid on 28 May 1958. She was launched on 9 July 1960, was sponsored by Mrs. Frederick Burdett Warder, and was commissioned on 3 August 1961, with Commander Dean L. Axene in command.
Early career
Thresher conducted lengthy sea trials in the western Atlantic and Caribbean Sea areas in 1961 and 1962. These tests provided a thorough evaluation of her many new and complex technological features and weapons. Following these trials, she took part in Nuclear Submarine Exercise (NUSUBEX) 3-61 off the northeastern coast of the United States from September 18 to September 24 1961.On October 18 Thresher headed south along the East Coast. While in port at San Juan, Puerto Rico on 2 November 1961, her reactor was shut down and the diesel generator was used to carry the "hotel" electrical loads. Several hours later the generator broke down, and the electrical load was then carried by the battery. The generator could not be quickly repaired, so the captain ordered the reactor restarted. However, the battery charge was depleted before the reactor reached criticality. With no electrical power for ventilation, temperatures in the machinery spaces reached 60C (140°F), and the boat was partially evacuated. Cavalla (SS-244) arrived the next morning and provided power from her diesel engines, enabling Thresher to restart her reactor.
Thresher conducted further trials and fired test torpedoes before returning to Portsmouth on November 29. The boat remained in port through the end of the year, and spent the first two months of 1962 evaluating her sonar and Submarine Rocket (SUBROC) systems. In March, the submarine participated in NUSUBEX 2-62 (an exercise designed to improve the tactical capabilities of nuclear submarines) and in antisubmarine warfare training with Task Group ALPHA.
Off Charleston, SC, the Thresher undertook operations observed by the Naval Antisubmarine Warfare Council before she returned briefly to New England waters, after which she proceeded to Florida for more SUBROC tests. However, while mooring at Port Canaveral, Florida, the submarine was accidentally struck by a tug which damaged one of her ballast tanks. After repairs at Groton, Connecticut, by the Electric Boat Company, the ship returned south for more tests and trials off Key West, Florida. Thresher then returned northward and remained in dockyard for refurbishment through the early spring of 1963.
Loss
On April 9, 1963, after the completion of this work, Thresher, now commanded by LCDR John Wesley Harvey, began post-overhaul trials. Accompanied by the submarine rescue ship USS Skylark (ASR-20), she sailed to an area some 350 km (220 miles) east of Cape Cod, Massachusetts, and on the morning of April 10 started deep-diving tests. As these proceeded, garbled communications were received over the underwater telephone by Skylark, indicating that after initial problems Thresher had tilted and the crew were attempting to regain control. A few words were understandable, including the famous final phrase "... minor difficulties, have positive up-angle, attempting to blow." When the garbled communications --- which were followed by the ominous sound of pressurized air escaping --- eventually ceased, it gradually transpired to surface observers that the Thresher had sunk. All 129 officers, crewmen and military and civilian technicians aboard her were lost.After an extensive underwater search using the bathyscaphe Trieste, oceanographic ship Mizar and other ships, Thresher’s remains were located on the sea floor, some 8,400 feet (2560 m) below the surface, in six major sections. The majority of the debris is in an area of about 134,000 m² (160,000 yd²). The major sections are the sail (the raised tower atop a submarine's main deck), sonar dome, bow section, engineering spaces section, operations spaces section, and the tail section. Deep sea photography, recovered artifacts, and an evaluation of her design and operational history permitted a Court of Inquiry to determine that the Thresher had probably sunk due to a joint failure in a salt water piping system, which relied heavily on silver brazing instead of welding; earlier tests with an ultrasound equipment found potential problems with about 14% of the tested brazed joints, most of which were determined to not pose a risk significant enough to require a repair. High-pressure water from a separated pipe apparently shorted out a nearby electrical panel, which caused a shutdown of the reactor. This casualty, in turn, led to subsequent loss of power and an inability to blow water from the ballast tanks fast enough to prevent the boat from sinking to a depth sufficient to cause a massive implosion. Death would have come instantly to everyone aboard. Over the next several years, the Navy implemented the SUBSAFE program to correct design and construction problems on all submarines (nuclear and diesel-electric) in service, under construction, and in planning. Apart from Scorpion, the U.S. Navy has suffered no further losses of the kind that ended Thresher’s brief service career.
The Navy has periodically monitored the environmental conditions of the site since the sinking and reported the results in an annual public report on environmental monitoring for U.S. Naval nuclear-powered ships. These reports provide specifics on the environmental sampling of sediment, water, and marine life which were taken to ascertain whether the submarine has had a significant effect on the deep ocean environment. The reports also explain the methodology for conducting deep sea monitoring from both surface vessels and submersibles. The monitoring data confirms that there has been no significant effect on the environment. Nuclear fuel in the submarine remains intact.
Details of the disaster
- 7:47 AM: Thresher begins its descent to the test depth of 1300 feet.
- 7:52 AM: Thresher levels off at 400 feet, contacts the surface, and the crew inspects the ship for leaks. None are found.
- 8:09 AM: Commander Harvey reports reaching half the test depth.
- 8:25 AM: Thresher reaches 1000 feet depth.
- 9:02 AM: Thresher cruises at 18 knots. Commander Harvey orders a course change: "Twenty degrees right rudder and five degrees down angle."
- 9:09 AM: A pipe bursts in the engine room, crew attempts to stop the leak while the room is filled with a cloud of mist. Harvey orders full speed, upward tilt of 15 degrees, and emptying the main ballast tank in order to surface. Due to Joule-Thomson effect, the pressurized air rapidly expanding in the pipes cools down, condensing moisture and depositing it on the filters installed in the valves; in about 90 seconds the moisture freezes, clogging the filters and blocking the air flow, halting the effort to blow water out of the ballast tanks; at that moment, the water leaking from the broken pipe causes short circuits leading to automatic shutdown of the ship reactor. The vessel loses its main propulsion system. Harvey orders unclutching of the main turbine and switch to battery power. The crew also attempts to restart the reactor, an operation that is expected to take at least 7 minutes.
- 9:13 AM: Harvey reports status via underwater telephone. The transmission is garbled, though some words are recognizable: "We are experiencing minor difficulties, have positive up-angle, and are attempting to blow." The submarine continues its descent. Another attempt to empty the ballast tanks is performed, again failing after about 60 seconds due to formation of ice.
- 9:15 AM: Skylark attempts to contact Thresher, gets no immediate answer.
- 9:16 AM: Garbled transmission received from Thresher.
- 9:17 AM: A second transmission is received, with somewhat recognizable phrase "exceeding test depth ... nine hundred north". The leak from the broken pipe grows with increased pressure.
- 9:18 AM: Skylark detects a high-energy low-frequency noise with characteristics of an implosion.
On April 11, at a news conference at 10:30 AM, the Navy officially concluded the ship lost.
Officers and men lost with USS Thresher (SSN-593)
The following crew members were lost with Thresher (SSN-593). NOTE: the designator "(SS)" after an enlisted man's name and rate denotes "Qualified in Submarines", and entitles the man to wear the coveted silver dolphin insignia.
Footnotes
See also
- Deep Submergence Rescue Vehicle
- USS Thresher for other ships of the same name
- USS Scorpion (SSN-589)
- John Craven USN Key individual in the search for Thresher
References
- Loss of USS Thresher: http://www.submarinehistory.com/Thresher.html
- Thresher-Scorpion Memorial: http://www.submarinehistory.com/ThresherScorpionMemorial.html
- World War II National Submarine Memorial - West: http://www.submarinehistory.com/WWIISubmarineMemorial.html
- World War II National Submarine Memorial - East: http://www.submarinehistory.com/WWIISubmarineMemorial-East.html
- Sontag, Sherry; Drew, Christopher; Drew, Annette Lawrence (1998). [[Blind Man's Bluff: The Untold Story of American Submarine Espionage]]. Harper. ISBN 0-06-103004-X.
External links
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