Remembering the Thresher


It’s been almost 50 years since USS Thresher (SSN-593) sank off the coast of Cape Cod, Massachusetts, claiming the lives of 129 Sailors and civilian technicians aboard.

USS Thresher
Starboard bow view, July 24, 1961. (Official U.S. Navy Photograph, from the collections of Naval History and Heritage Command)

Family members and dignitaries will remember the loss that led to a renowned submarine safety program during a ceremony this Saturday at 1 p.m. EDT in Portsmouth, Maine.

Thresher, which was built at Portsmouth Naval Shipyard, Kittery, Maine, was the lead ship of a class of 3700-ton nuclear-powered attack submarines.

On April 10, 1963, Thresher began post-overhaul trials following lengthy testing and throughout evaluation of her many new technological features and weapons after her commissioning in August 1961.

Thresher transited with the submarine rescue ship Skylark (ASR-20) to an area approximately 220 miles east of Cape Cod and started deep-diving tests. Fifteen minutes after reaching her assigned test depth, Thresher informed Skylark of difficulties. Garbled transmissions indicated things were going wrong. Suddenly, listeners in Skylark heard a noise “like air rushing into an air tank” and then silence.

Thresher search party
Navy ships circle in the vicinity of the site of Thresher’s sinking, April 15, 1963, five days after her loss. (Official U.S. Navy photograph from the collections of Naval History and Heritage Command)

Efforts to reestablish contact with Thresher failed. A search group was formed to locate the submarine. Rescue ship Recovery (ASR-43) retrieved bits of debris, including gloves and bits of internal insulation. Photographs taken by bathyscaph Trieste proved the submarine had broken up, claiming all hands on board.

Thresher was officially declared lost April 12, 1963.

USS Thresher Press Release


A Court of Inquiry was convened and determined the loss was in all probability due to a casting, piping or welding failure that flooded the engine room with water. This water probably caused electrical failures that automatically shut down the nuclear reactor, causing an initial power loss and the eventual loss of the boat.

Almost two months after Thresher’s loss, the Navy’s Submarine Safety Program, also known as SUBSAFE, was created. The program established:
1) Submarine design requirements
2) Initial SUBSAFE certification requirements with a supporting process
3) Certification continuity requirements with a supporting process

Over the next several years, a massive program was undertaken to correct design and construction problems on the Navy’s existing nuclear submarines, and on those under construction and in planning.

The SUBSAFE program has been very successful. Between 1915 and 1963, 16 submarines were lost due to non-combat causes, an average of one every three years. Since the program’s implementation in 1963, no SUBSAFE-certified submarines have been lost.

At a ceremony commemorating the 25th anniversary of Thresher’s loss, the Navy’s ranking submarine officer in 1988, Admiral Bruce Demars, said, “The loss of Thresher initiated fundamental changes in the way we do business, changes in design, construction, inspections, safety checks, tests and more. We have not forgotten the lesson learned. It’s a much safer submarine force today.”

Source: Navy History and Heritage Command

For additional information, see the Thresher entry on Wikipedia.