April 10th of this year will mark the 50th anniversary of the sinking of the USS Thresher. She is the first and only one of two losses the United States has ever suffered of a nuclear powered submarine.
The USS Thresher, was the lead ship of a class (Thresher Class) of 3700-ton nuclear-powered attack submarines and was built at the Portsmouth Naval Shipyard, Kittery, Maine. The keel was initially laid in 1958 and the submarine was commissioned in August 1961. After that she conducted lengthy trials in the western Atlantic and Caribbean areas in 1961 and 1962, providing a thorough evaluation of her many new technological features and weapons, which is the norm for a newly built submarine. After the completion of these test operations, the Thresher returned to her builders for an overhaul. On 10 April 1963, after the completion of this work, the Thresher began post-overhaul trials. Accompanied by the submarine rescue ship Skylark (ASR-20), she transited to an area some 220 miles east of Cape Cod, Massachusetts, and started deep-diving tests. As these proceeded, garbled communications were received by Skylark, indicating trouble aboard the submarine. At approximately 9:17 am the Skylark received the partially recognizable transmission that the Thresher was exceeding her test depth. This was probably around 1300 or so feet down. Her crush depth was somewhere around 1600-1750 feet down. Then a few minutes later, listeners on the Skylark reported a sound like “air rushing into an air tank.” This would have been the bubble pulse emitted when the Thresher imploded. It gradually became apparent that she had sunk, taking the lives of 129 officers, crewmen and civilian technicians.
After an extensive underwater search utilizing the bathyscaphe Trieste, oceanographic ship Mizar, and other ships, Thresher’s shattered remains were located on the sea floor, some 8400 feet below the surface. Deep sea photography, recovered artifacts and an evaluation of her design and operations permitted a Court of Inquiry to determine that she had probably sunk due to a piping failure, subsequent loss of power and inability to blow ballast tanks rapidly enough to avoid sinking. 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. Following completion of this “SubSafe” effort, the Navy has suffered no further losses of the kind that so tragically ended Thresher’s brief service career and the lives of 129 brave men.
The Navy continues to monitor the wreckage sites of both the Thresher and the Scorpion (lost in 1968) to test for nuclear contamination from their reactors, and in the case of the Scorpion the two nuclear warheads she was carrying. To date the contamination has been listed as minute.