What we really learned from Thresher

“When fact, supposition, and speculation are properly separated, you will find that the known facts are so meager it is almost impossible to tell what was happening aboard Thresher at the critical time.” We risk taking for granted the fundamental things we learned about the requirements of modern technology and the need to change our management concepts to keep pace with technology of our high-performance ships. It occurred to me that we don’t emphasize enough the key lessons and we are at risk of the next generation only hearing “Don’t do a Thresher” without people clearly understanding what they must do (or not do). The prepared statement for Congressional testimony on the correction of Thresher deficiencies was 23 pages long. Why was the discussion of items to correct so long? “The loss of the Thresher should not be viewed solely as the result of failure of a specific braze, weld, system, or component, but rather should be considered a consequence of the philosophy of design, construction, and inspection, that was permitted in naval shipbuilding programs at the time.” Rickover believed it was important to reevaluate practices where, in the desire to make advancements, the Navy may have forsaken the fundamentals of good engineering. For example, practices that led to the under-design of the emergency ballast system, the failure to follow up on the unexpected failures of silver brazed joints in sea water systems, and the attitude that specifications were merely goals to shoot for, did not need to be taken literally, and failure to meet them did not have to be cleared through the Bureau of Ships.

Basic things we know about the events at the critical time of the loss of the Thresher

On April 10, 1963, the USS Thresher sank 220 miles off the coast of Cape Cod with 129 men aboard. There were no survivors to tell what had happened in what was then the worst submarine disaster in U.S. history. Hours after the tragedy a Navy court of inquiry was formed to investigate and hear evidence about the sinking. The five-member court heard 120 witnesses and collected 255 exhibits over eight weeks, most of it behind closed doors.

The court of inquiry concluded that a flooding casualty, reported in the last communication from Thresher, in the engineroom is the most probable cause of the sinking of Thresher and that it is most likely that a piping system failure had occurred in one of the Thresher salt water systems, probably in the engineroom. It was also concluded that water probably affected electrical circuits and caused a loss of power. It is likely the ship had several hundred substandard silver-brazed seawater joints when she last went to sea.

Key points:

  • Thresher was [and remains] a warning made at great sacrifice of life, that we had to change our way of doing business to meet the requirements of modern technology and high-performance ships. [We permitted] the accumulation of conditions that permitted the inadequate design, poor fabrication methods and incomplete inspection to exist that lead to Thresher. – Admiral Rickover
  • [W]hile nuclear power was revolutionizing the submarine as a weapons system during the past 10 years, the more conventional aspects of the submarine and its safety devices were not keeping pace with the more stringent performance requirements of greater endurance, higher speed, and deeper submergence. For example, the design and limited blowing capability of the deballasting system which might have been adequate for the World War II and postwar conventional submarines were inadequate as an emergency system for the larger, deeper diving, higher performance nuclear submarines.
  • It has been difficult and time consuming to insure that shipyards met the specification requirements in the area of pipe welding under my cognizance. In many instances we had to overcome the prevalent attitude that specifications were merely a goal to shoot for, and did not need to be taken literally. This was aggravated by the opinion, also prevalent, that the quality of welding and inspection required by the specifications was unnecessarily stringent. – Admiral Rickover
  • I consider that the most important step to be taken by the Navy [to reduce the risk of additional accidents such as the Thresher] is to eliminate transient technical management. No industrial organization that operates on a profit and loss basis would ever dream of continually shifting its top people. An industrial organization so operated would soon go out of business. Changing this concept of transient technical management in the Navy will be difficult. I doubt the Navy, if left to itself, will do this in a timely manner. A substantially contemporaneous transfer of Thresher's commanding officer and executive officer and ship's superintendent and assistant ship's superintendent in the final stages was not conducive to optimum completion of the work undertaken. – Admiral Rickover
  • Another factor I believe to be responsible for many of the Navy's technical difficulties is the lack of individual responsibility. For example, during the 5 to 6 years encompassed in the design, construction, and evaluation of the Thresher, some of the key job changes were approximately as follows: The Portsmouth Naval Shipyard, which was assigned the detail design responsibility for the Thresher, had three shipyard commanders, three production officers, five planning officers, and three design superintendents. The Bureau of Ships during this period had two Chiefs of Bureau, six or so heads of the Design, Division, and three heads of the submarine type desk. Some of the Individual Bureau technical codes concerned with the Thresher had about four to six changes of management during this same period. – Admiral Rickover
  • The Court of Inquiry on Thresher recommended [that] the Bureau of Ships … require submarine shipbuilding activities to adhere to specifications, and to obtain from it approval for all waivers where this is not practicable. The Bureau of Ships should increase its audit activity to insure adherence to specifications for submarine building, overhaul, and repair.
  • During the recent stay of Thresher at Portsmouth about 5 percent of her silver-brazed joints were ultrasonically inspected. These joints were in critical piping systems, 2-inch diameter or larger. The inspection revealed that about 10 percent of those checked required repair or replacement. If the quality of the joints so inspected was representative of all the Thresher's silver-brazed joints this means that the ship had several hundred substandard joints when she last went to sea. More joints were not tested. This decision was not made by the shipyard commander, but he effectively assumed responsibility for the decision because he did have knowledge of it. The court of inquiry concluded he used poor judgment [for] not continuing those tests. In retrospect, [he] admitted that he thought he should have looked into this more thoroughly, but at the time he did not consider it a dangerous situation. They were trying to meet a deadline date for the completion of the ship's availability, and to have gone further with the testing would have required unlagging of piping and delaying the ship and running up the cost of the overhaul. It seems unthinkable now that anyone would just stop investigating a problem because time had run out, but this shows how far we have come. This is why we regularly ask, "What else could be wrong?" and "Where else do we have this problem?" even though it takes some time and pain to answer those questions.
  • I consider that when sampling techniques are used to ascertain if flaws exist, the findings of such flaws should be followed by extensive additional inspections. – Admiral Rickover
  • … The real lesson to be learned is that we must change our way of doing business to meet the requirements of present-day technology. … What I have actually done in the nuclear program is primarily to insist that everyone concerned meet the Navy specifications -- specifications which had been in existence for many years. It is only when I required people to comply with these specifications that I uncovered the carelessness, looseness, and poor practices that have obtained in our shipbuilding business. … That is the crux of the problem. - Admiral Rickover.
  • … One of the questions that should result from this testimony … is why it has been necessary to have a 23-page discussion of items that are now being corrected as a result of the loss of Thresher. Unless we find the answer to that question, we cannot be sure that we have taken all steps necessary to prevent another accident. While we may never know the specific failure which was the cause of the Thresher's loss, we should be able to reach a better understanding of the conditions which make such failures possible, and then do everything we canto prevent their recurrence. - Admiral Rickover.
  • … I believe the loss of the Thresher should not be viewed solely as the result of failure of a specific braze, weld, system, or component, but rather should be considered a consequence of the philosophy of design, construction, and inspection, that has been permitted in our naval shipbuilding programs. I think it is important that we reevaluate our present practices where, in the desire to make advancements, we may have forsaken the fundamentals of good engineering.

I have placed the rest of the notes I excerpted from the Hearings Before the Joint Committee on Atomic Energy in this file to keep this post from being excessively long. I encourage you to look at the notes and possibly to review the transcript of the Congressional hearings.