USS Thresher (SSN 593)

Career
Flag |
Owner |  United States Navy
Shipyard |  Portsmouth Naval Shipyard
Portsmouth, New Hampshire
Type |  Submarine (nuclear-powered)
Thresher / Permit-class
Keel laid |  28 May 1958
Launched |  9 July 1960
Commissioned |  3 August 1961
Status |  Sunk during deep dive test
10 April 1963
Characteristics
Displacement |  3,700 t suface
4,300 t submerged
Length |  278 ft 6 in
Beam |  31 ft 8 in
Speed |  20+ knots
Armament |  Four torpedo tubes
Crew |  100 officers and men

USS Thresher (SSN 593) was a nuclear-powered submarine in the United States Navy and the lead boat of its class, but was noted for its sudden sinking in 1963, taking 129 crew and civilians down with her and shocking the nation.

## Contents

* 1 History
* 2 Sinking
* 3 Aftermath
* 4 References

## History[edit]

The second submarine to bear the name Thresher, she was laid down on 28 May 1958 by the Portsmouth, New Hampshire Naval Shipyard; launched on 9 July 1960; sponsored by Mrs. Frederick B. Warder; and commissioned on 3 August 1961, Commander Dean W. Axene in command.

Following trials the nuclear attack submarine took part in Nuclear submarine Exercise (NUSUBEX) 3-61 off the northeastern coast of the United States from 18 to 24 September.

On 18 October; the submarine headed south along the east coast. After calling at San Juan, Puerto Rico, she conducted further trials and test-fired her torpedo system before returning to Portsmouth on 29 November. The ship remained in port through the end of the year and spent the first two months of 1962 evaluating her sonar system and her Submarine Rocket (SUBROC) system. 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, the ship undertook operations observed by the Naval Antisubmarine Warfare Council, before she returned briefly to New England waters from whence she proceeded to Florida for SUBROC tests. However, while mooring at Port Canaveral, the submarine was accidentally struck by a tug which damaged one of her ballast tanks. After repairs at Groton, Conn., by the Electric Boat Company, the sub returned south for more tests and trials off Key West. Thresher then returned northward and remained in dockyard hands through the early spring of 1963.

## Sinking[edit]

In company with USS Skylark (ASR-20), Thresher put to sea on 10 April 1963 for deep-diving exercises. In addition to her 16 officers and 96 enlisted men, the submarine carried 17 civilian technicians to observe her performance during the deep-diving tests.

Fifteen minutes after reaching her assigned test depth, the submarine communicated with Skylark by underwater telephone, apprizing the submarine rescue ship of difficulties. Garbled transmissions indicated that far below the surface things were going badly wrong. Suddenly, listeners in Skylark heard a noise "like air rushing into an air tank", then silence.

Efforts to reestablish contact with Thresher failed, and a search group was formed in an attempt to locate the submarine. Rescue ship USS Recovery (ASR-43) subsequently recovered bits of debris, including gloves and bits of internal insulation. Photographs taken by bathyscaph Trieste proved that the submarine had broken up, taking all hands on board to their deaths in 5,500 of water, some 220 miles east of Boston. Thresher was officially declared lost in April 1963.

Subsequently, a Court of Inquiry was convened and, after studying pictures and other data, opined that the loss of Thresher was in all probability due to a silver-brazed piping joint welding failure that flooded the engine room with water. Salt water spray on electrical components caused short circuits, reactor shutdown and loss of propulsion power. The main ballast tank blow system then malfunctioned, most probably owing to ice formation in the piping, and the inadequate blow rate could not overcome resulting in flooding in the engine room.

Thresher is in six major sections on the ocean floor, with the majority in a single debris field about 400 yards square. The major sections are the sail, sonar dome, bow section, engineering spaces, operations spaces, and the tail section.

Owing to the pressurized-water nuclear reactor in the engine room, deep ocean radiological monitoring operations were conducted in August 1983 and August 1986. The site had been previously monitored in 1965 and 1977 and none of the samples obtained showed any evidence of release of radioactivity from the reactor fuel elements. Fission products were not detected above concentrations typical of worldwide background levels in sediment, water, or marine life samples.

## Aftermath[edit]

The Navy implemented the SUBSAFE Program by December, 1963. Essentially a series of tests required on all parts and materials going into a submarine, no sub since Thresher was lost after being SUBSAFE-certified (the lone exception, USS Scorpion, did not go through certification).

Sadly, the Thresher-class was renamed Permit, after the next boat in line.

## References[edit]

* SUBSAFE Program, from Naval Sea Systems Command

Copyright Details

License:  |  This work is in the Public Domain in the United States because it is a work of the United States Federal Government under the terms of Title 17, Chapter 1, Section 105 of the U.S. Code
Source:  |  File available from the United States Federal Government [1].