The Death of the USS Thresher - Norman Polmar The Thresher came alive in 1963. It was to be a short life. Manufactured from the new “stronger steel—the so-called HY-80 steel which could withstand the pressure of 80,000 pounds per square inch before it would start pulling apart. With a submarine hull built for deeper operation the Navy would get a bonus with the Thresher. Because of her hull strength, in shallow waters she would be able to withstand greater shocks from enemy weapons.” The decision to emphasise depth was controversial. Rickover, in particular, thought the Navy was wasting its money, but the idea was, as a hunter-killer attack sub, that Thresher could hide deep, way below the thermal layers.

Polmar, an excellent naval writer who wrote a terrific biography of Rickover, Rickover: Controversy and Genius: A Biography takes us through the short life of the Thresher. One wonders if any one of several items might have hastened the boat’s demise: the accidental collision with a tugboat in Florida which required rewelding of the outer hull; the explosion tests intended to see what the effects of underwater explosions might be ( “There was no question that the Thresher suffered damage,” he said. “But it was all relatively minor.... The damage we sustained did not impair the ship’s ability to operate, and much of it, such as the damage to vital sonar tubes, we could repair ourselves with our store of spare parts.”)--perhaps one of the internal pipes was damaged; the refit itself, which required cutting holes in the sub to move equipment in and out, and removing and reconnected hundreds of internal pipes; too hasty to test at “test” depth (the maximum depth a sub is never supposed to exceed, in Thresher’s case about 1300 feet. “Below test depth the fittings and pipes on the submarine begin to give way.” Was it any one of these events or a subtle combination thereof?

There was the usual, “golly gee everyone was great, the ship-builders were the best, the crew was the greatest, the boat was perfect, yadayadayada.” (“Captain William Heronemus, testified next. As the repair and ship-building superintendent of the Portsmouth yard, he was intimately familiar with the work that had been done on the Thresher during the past nine months. “I have known no other ship in a higher state of readiness for sea than the Thresher.”) Yet several contrarian tidbits did leak out: the laissez faire attitude of many of the workmen during the refit; the astonishing number of hydraulic vlaves that had been installed backwards (20%, but they got them all corrected before the final dive, yeah right.) A retired CPO who lost two brothers on the Thresher, both CPO’s, Joseph Shafer noted, “ that his brothers were “not sure” that people who worked on the Thresher during her overhaul had done their job. He said there was a jocular attitude of “what’s going to be wrong this time” on the part of his late brothers. David Main, a welder at the Electric Boat yard and a brother-in-law of the Shafers, substantiated the testimony of Joseph Shafer regarding his brothers.” Others testified, “that there had been trouble with a main sea water valve in the Thresher during the nine months the submarine was undergoing overhaul. This was a large valve that admitted water for several of the submarine’s cooling systems. Lieutenant McCoole also said that the air systems of the Thresher had been a continuing problem; that there had been errors in the indicators that showed whether or not the submarine was on an even keel...”

Lieutenant Commander William J. Cowhill, executive officer of the submarine from March 1962, to January 1963 rated the Thresher’s construction and overhaul work at the Portsmouth yard as excellent—“with one reservation, the silver brazing process on piping.” Silver brazing is the process of joining pipes on submarines with silver solder instead of the more common lead solder. The silver solder melts at a higher temperature than lead and gives a much stronger joint. There were hundreds of silver brazed joints in the maze of pipes in the Thresher, many of them on pipes that penetrated the craft’s pressure hull.

Polmar does present alternative scenarios based on the skimpy evidence but all related to the last transmission which described having a “minor problem.” Polmar doubts a pipe fracture letting in a high pressure stream of water as being described as “minor” by any submariner. His suggestion: reactor failure, due perhaps to a stream of water, that might have prevented operating the diving planes (no battery backup?) which in turn led to loss of forward motion causing it to sink, the attempt to blow the ballast tanks which might have failed due to freezing (it was later discovered that blowing the tanks at such a depth was rarely successful.)

I was astonished at the revelations regarding sabotage against U.S. subs. At that time a hose used to test the submarine’s evaporators was cut. The Navy said later that a crew member was responsible, but refused to give any details. Intentional damage was also reported aboard the nuclear-propelled submarine Snook. On December 21, 1959, while the Snook was in drydock at Pascagoula, Mississippi, it was discovered that someone had cut through the elbow of some piping in the submarine. Less than a month after the Snook incident possible sabotage was discovered aboard the nuclear-propelled missile cruiser Long Beach. The then-unfinished Long Beach was at Quincy, Massachusetts, when it was discovered that a 3½-inch armored anti-mine cable had been cut in three places. Although termed “relatively insignificant,” this incident was also carefully investigated by the FBI as well as by Naval Intelligence. Sabotage is usually connected with a deliberate attempt by an enemy agent. However, because of the circumstances it is generally accepted that these incidents were a form of adult vandalism or mischievousness on the part of a civilian worker or possibly naval personnel. It appears the purpose of the sabotage was to delay the ships involved rather than to cause their loss. Numerous other incidents were detailed, but the idea that workmen might do such actions boggles the mind. Rickover testified before Congress (admittedly in a self-serving manner since he was warding off any blame that might have been attached to the nuclear power plant): “ the lack of adequate welding techniques of the critical piping that penetrated the submarine’s pressure hull; the poor management and quality control in submarine construction; and the manner in which the Navy’s leadership made decisions about submarine requirements [including too frequent rotations]. Admiral Rickover was correct in his accusations—there were problems in all of those areas.”

I was a little disappointed in Polmar’s account of the inquiry. It was just a chronological, very brief, recounting of the testimony. The actual transcript ran to more than 1500 pages. I wanted a more detailed and critical review of that inquiry. The formal conclusion was that a silver brazed weld must have given way at test depth resulting in an unstoppable flow of water that rendered the boat uncontrollable and it sank below crush depth.