594 Tough Thresher’s Loss
April 10, 2019 marks the 56th anniversary of one of the most tragic moments in US Submaine Service history, the follow is more of an excerpt from first narrative (still working on it!) my new series 594 Tough
On 10 April, 1963, the USS Thresher SSN-593, accompanied by the submarine rescue ship USS Skylark ASR-20, was nearly 200 nautical miles east of Cape Cod conducting post overhaul trials. Aboard were 129 men, which included “riders” from the Portsmouth Naval Yard (PNY), along to oversee, adjust, or fix any of the newly installed or refurbished equipment. A lot was riding on Thresher’s performance that morning including the direction of the nuclear submarine fleet. Thresher was the first of a whole new breed nuclear submarine known as a “hunter/killer, fast attack.” While the USS Nautilus (SSN-571) ushered in nuclear propulsion aboard submarines, and the four-boat Skate class (SSN-578) had proven nuclear propulsion a viability for repeatable production, then the six Skipjacks (SSN-585) advanced speed and performance with a more efficient hull design, Thresher leaped submarine technology beyond these past achievements to a whole new paradigm. Thresher was born out of a 1956 Cold War study (Project Nobska, or Nobska Committee, or Nobska Study) developed by the leading scientist, engineers, and naval officers of the time, who analyzed and compiled criteria on the expected threats facing submarines in the coming decades, and put forth recommendations as to best counter them. Among the several recommendations, that became part of Thresher, was:
(1) A layout optimized for the newest sonar systems, specifically configured for hunting other submarines.
(2) A robustness and versatility for handling a mix of the latest weapons, as well as adaptability for future weapons still in conceptual stages.
(3) A hull profile optimized for performance and speed, which became an elongated adaptation of the new “teardrop” shape with single propellor, first successfully employed in the experimental Albacore (AGSS-569), then utilized in production with the diesel/electric Barbel class (SS-580) and the nuclear powered Skipjacks. This gave Thresher unprecedented maneuverability and speeds, unofficially listed as 29 to 30 knots, which was comparable to those achieved by the fastest boats, the Skipjacks (unofficially listed as 32 to 33 knots).
(4) The hull was to be constructed of the strongest materials then available, so a new grade of low carbon/high yield steel, known as HY-80 (per MIL-S-16216K Yield Strength: 80 ksi/Ultimate Tensile Strength: approximately 130-145 ksi [when specified]) was employed. This new grade gave the Thresher an unprecedented operational depth of 1,300 feet, at a time when the average diving depth for new construction was rated at 750 to 800 feet.
(5) But the greatest effect of the study, and Thresher’s most enduring feature, was the level of detail placed on stealth and silencing; simply put noise is the enemy of the submariner. Noise not only gives away a submarine’s position, it also robs a boat of clear sonar reception when stalking an enemy. In the Thresher, all major propulsion machinery (reduction gearing, pumps, compressors, turbines, etc.) was isolated from the hull on a large shock absorbing platform, known as a “raft.” She received a specially configured seven-bladed propeller to reduce the effects of cavitation and disturbance when cutting through her own flow stream. Decks and bulkheads, where applicable, were fitted with sound absorbing materials. Even bolt joints, were fitted with rubber washers.
The results incorporated, made Thresher the most advanced and lethal submarine ever constructed to that time. Yet for all her technical innovations, her first year-and-a-half in commission had not been as successful as the Navy had hoped. She had been plagued with several major issues, and started to gain a reputation as an unlucky boat. And, with the addition three sister boats already in commission (Permit, Plunger, and Barb), plus more building, the Navy was placing a lot in the just-completed overhaul at PNY. So, at around 0630 local time Thresher began her decent for deep submergence testing. She maintained communications with Skylark via an underwater telephone system known as ”Gertrude.” Thresher would descend in 100-foot increments, stop, and check critical systems for integrity before continuing deeper. As Thresher neared her test depth, Skylark began to receive garbled responses, but enough got through to indicate the submarine was in trouble and unable to return to the surface, despite an attempt at an emergency-blow of her main ballast tanks. Soon there was only silence on Gertrude, and with no further responses from Thresher, the crew on Skylark knew the submarine was lost with all hands.
The story of Thresher though tragic does not end here, https://www.ssnsdbooksoffer.com/post/594-tough
Copyright 2019 JP Ronald.