Thoughts on THRESHER

by Will Davis

USS THRESHER SSN 593 underway

USS THRESHER; official United States Navy photo, from collection of Naval Historical Center via

As is the case on every 10APR, I find myself – even in the midst of the present national and, really, worldwide crisis – returning to thoughts of the USS THRESHER on this date in 1963.  All of us who have been through the Naval Nuclear Power Program and served in submarines are aware to greater or lesser extent what happened; my experience, having served aboard one of the SUBSAFE boats whose development was a direct result of the accident, lends perhaps to more sustained reflection.


The events of that day in 1963 are essentially these:  USS THRESHER, the first of a new class of deep diving submarines (and really, a wholly new weapon just as had been USS NAUTILUS) had already been in service for some time and in fact had been through an extended shipyard period for considerable work.  New sea trials were needed to effectively recertify THRESHER.   The boat (we called them “boats” when I was in) was conducting what we call a “deep dive” or a dive down to test depth – that’s the deepest depth at which a submarine is designed to operated.  Somewhat below that is collapse depth, which is the depth at which the pressure hull is expected to fail.

As the boat dove for that last time, USS SKYLARK, the escorting surface ship for the mission, maintained contact on the then-used underwater telephone that allowed voice communication through the water.  THRESHER reported that it was commencing its deep dive test just after 7:45 AM that morning, and for an hour and a half nothing seemed out of the ordinary as THRESHER snuck down to her test depth.  However, at 9:13 AM SKYLARK received a transmission from THRESHER:

“Experiencing minor difficulties.  Have positive up angle.  Am attempting to blow.  Will keep you informed.”

The sound of compressed air was heard over the phone next, surely the first attempt to blow the main ballast tanks – which immediately became impossible as the lines froze, as later testing on other identical boats would prove.  At 9:16 AM SKYLARK heard a garbled message relating to test depth, and shortly another very garbled message containing the number 900 – possibly, a reference to exceeding test depth by 900 feet.  At 9:18 AM, 10 April 1963, SKYLARK sonar operators clearly heard a violent underwater burst or explosion which was immediately recognized as an implosion.  USS THRESHER had been lost with 129 souls on board.

Thoughts Today

The only thing of which we can be certain was already augured during hearings before the Joint Committee on Atomic Energy in 1964 – that we will never know exactly what was transpiring on board during those last moments.  Various theories have emerged, either including or supposedly ruling out flooding (inrush of seawater from a failed pipe exposed to sea pressure, spraying equipment, weighing down the boat, and causing associated system failures.)  It is obvious something was happening that caused the Captain to blow the main ballast tanks, but what was happening exactly and what the Captain knew about what was happening from the control room is impossible to know.

Much effort went into trying to figure out what MIGHT have happened – a huge gamble in many ways since no one knew what to fix.  Worse, many submarines had been ordered to roughly the same design and a number of similarly equipped ballistic missile subs was also on the way.  A number of observations, relevant today to any nuclear or for that matter industrial enterprise came out and were published at various points in the Congressional record.  I’d like to close today by offering some of these points as things to think about.

•Admiral Rickover had a number of silver-brazed seawater and other piping system joints examined on THRESHER and found an alarming number unacceptable; he told the JCAE in 1964 that THRESHER might have gone to sea with hundreds of substandard joints over which he had no jurisdiction.  His remarks to the JCAE pointed up a continued substandard performance by shipyard workers who now worked in an industry in which zero error was permissible.  Changing standards over time as nuclear subs became the norm (over diesel subs) and modulating requirements had thus caught up to and then exceeded the professional standards and capabilities of many shipyard workers whose standards had stood still.

•Rickover had tried to push hard with NAUTILUS and then again with THRESHER to get those in charge, namely the Bureau of Ships, as well as everyone else to understand that each of these evolutionary steps was a wholly new weapon and not just a regular boat with a nuclear powered back end.  One Senator remarked during hearings that he’d long ago seen a newfangled “horseless carriage” which was little more than a buggy with a gasoline engine fitted and wondered if the Navy wasn’t doing the same sort of bungled approach with nuclear submarines.  Game changing innovations require top to bottom reassessment of entire platforms.  Failure to grasp this had caused the Navy much headache post-NAUTILUS and had apparently now lost them an entire crew (and a group of civilian technicians riding THRESHER to check out contracted systems.)

•The rapid multiplication of nuclear submarines as had been ordered by the Executive Branch and approved by Congress was not leading to a rapid improvement in construction skills; instead, it was leading to a rapid intensification of problems with individual boats that could not be fixed by simply enforcing present standards.  A new overall, and somewhat heavy handed approach would be needed to hammer home the requirements for each and every weld, every bolt, every component that could affect a boat’s watertight integrity.  This was the spark of what became SUBSAFE – which is the most successful Navy quality program that should never have had to happen in the first place.  We may all have heard someone say something along the lines of “well they don’t put those gates and signals at a railroad crossing until someone gets killed there” which, in fact, is not true, but we do all realize that sometimes a massive shakeup is required to get attention and refocus priorities.  In the Navy’s new nuclear submarine program, which it SHOULD have recognized as a wholly new venture, the loss of the THRESHER was its own “Three Mile Island” moment.  Rapidly expanding programs will exacerbate, rather than somehow inherently improve, lack of talent and adherence to standards – a problem the Navy fixed.  Other various industrial programs have, and have not, responded to their “TMI” or “THRESHER” moments as well.

So, as I sit here today thinking and, for once, writing publicly about the loss of THRESHER all those years ago I wonder in today’s Navy how much the young sailors know today, all these years later, about THRESHER   I would have to imagine, given the exemplary record since (one further nuclear boat, USS SCORPION, lost to an operational accident in 1968 and one serious fire on the diesel powered USS BONEFISH in the 1980’s) that the loss of THRESHER and her fine crew has not been entirely in vain.  It is important that the crew of THRESHER is remembered, but perhaps it’s even more important that it never happens again.

Will DavisWill Davis has been a member of the Board of Directors for the N/S Savannah Association, Inc. He has been a contributing author for Fuel Cycle Week, and wrote his own popular blog Atomic Power Review. Davis is also a consultant and writer for the American Nuclear Society, and serves as Vice Chair of ANS’ Book Publishing Committee. He is a former U.S. Navy reactor operator and served on SSBN-641, USS Simon Bolivar.  His popular Twitter account, @atomicnews is mostly devoted to nuclear energy.  He likes to collect typewriters and early pocket calculators, which are piling up.

About Will Davis

Will Davis is the Communications Director for the N/S Savannah Association, Inc. where he also serves as historian, newsletter editor and member of the board of directors. Davis has recently been engaged by the Global America Business Institute as a consultant. He is also a consultant to, and writer for, the American Nuclear Society; an active ANS member, he is serving on the ANS Communications Committee 2013–2016. In addition, he is a contributing author for Fuel Cycle Week, and writes his own popular blog Atomic Power Review. Davis is a former US Navy reactor operator, qualified on S8G and S5W plants.

15 thoughts on “Thoughts on THRESHER

  1. Will Davis Post author

    Hi there! NS SAVANNAH is in Baltimore undergoing the nuclear decommissioning. With any luck the ship will be donated by MARAD to some entity and preserved. But that’s not by any degree guaranteed.

  2. Will Davis Post author

    The seawater system and other brazed joints were in fact examined on board THRESHER prior to her final patrol, in an “unofficial” set of tests conducted on the orders of Rickover himself. This is proven in his testimony to the Joint Committee on Atomic Energy after the ship’s loss.

  3. Will Davis Post author

    I am quite familiar with Rule’s theorizing on THRESHER, and frankly his analysis falls short. For example, there’s no reason that MCP frequency varied (as he and his acolytes frequently point out) for a significant period of time without some other failure. Further, Rule rules out any sort of flooding, but failed condenser tubes might give exactly the frequency response detailed in his writings. I am of the mind that the THRESHER probably suffered something else, such as jammed planes and then stopped. Likely having gone down heavy, she developed a sink rate which then led to system failures and then the attempt to blow which, as we know, failed.

  4. Tom Stevens

    Your article brings back many recollections and thoughts of tribute to our sailors— thanks. One memory on the light side is from 1966 or 67 soon after I had arrived at NR for what turned out to be the start of a 48 year career in nuclear power. I was in a discussion with a very patient senior engineer at EB, Marv Schutt, and he explained to me I needn’t worry that we were designing something to be SUBSAFE. It did not mean “less than safe!” I learned a lot from Marv and his colleagues. Thanks again for the recollections.

  5. Alan Chodorow

    Thanks to you, Mr. Davis, for remembering the Thresher . It was a day that is never out of my mind. I received my dolphins at lunch that day — on the USS PERMIT. We were in port with the reactor shutdown, and all the other officers left the boat after lunch. A few hours later, we received a message from COMSUBLANT reporting the loss and asking for opinions about the cause. I had been a real submariner for just a few hours. I had thoughts, but was terrified at the the idea of sending them on my own to SUBLANT. All that I could think about finding the Captain, and fortunately the finding effort succeeded.


  6. Joseph DeBor

    Mr. Davis, good article on Thresher. I spent much of my post SSBN 622 career inspecting human-factors engineering in civilian power plants (US, Spain, Ukraine). I was lucky to meet a number of our Russian nuke counterparts in Ukraine. They also appreciated the need for maintain the highest level of standards.

    Thanks, Joseph DeBor

  7. Dennis Mosebey

    The sil brazed joint failure theory is being challenged by Bruce Rule in Why USS Thresher was Lost and by James Bryant USN Capt, retired who just won a FOI suit against Navy for rest of classified information Mr. Rule was head sonar analyst for Naval Intelligence and detected at time of loss Ronald for fast speed pump operation . No subsequent slow speed finals were detected. Cause of loss is scram of unknown origin with pumps in fast speed which caused loss of motor generator sets and loss of all AC power. We know it must have been a scram because after blow failed zThredher could have driven herself out of danger if she had propulsion. Since she did not she exceeded collapse death. Pictures of wreckage taken by. Bob Ballard support the boat was not significantly flooded as debris field is scattered out like a classic implosion . This would not have happened had there been massive seawater joint failure. At the time there was no fast scram recovery procedure and in fact it was initiated after her loss by Naval Reactors. I recommend to you Mr Rule’s analysis both on Thresher and one on Scorpion as definitive current works on loss of these two boats Finally Thresher collapsed below her collapse depth indicating shipyard workers did more than a good job on her and they have gotten a bum rap all these years! Thanks for reflections on her and your overall points are correct and well founded

  8. Thomas L. Sanders

    I was in Nuke school when the Scorpion was lost and later served
    on the USS Kamehameha, SSBN 642 and the USS Shark, SSN 591, the Scorpion’s sister boat.
    We at the time learned a lot about Thresher and Scorpion during sub school. I hope the new generation is also being well informed including the advancements that were implemented over time

    Thanks for your article

    Tom Sanders
    Former President, ANS

  9. Mark Forssell

    Will, Your statement about the Thresher included that Rickover had “joints examined on Thresher”. Obviously, the piping on the Thresher could not be examined since the boat is still on the bottom of the ocean. A simple word change can fix that problem.

  10. Charles Bergeron

    Thanks for the reminder Will. I became qualified as a Bettis JTG member and Technical Adviser in 1967 during the “100 boat buildup” and roll out of the “Sub Safe” changes. I was responsible for approximately 20 sub programs and held the most task qualifications in the Rickover Program at the time I transitioned to commercial NP. Shortly after TMI, I participated in the inception of INPO to help bring the “Sub Safe” Rickover culture into commercial power. I initiated the request to Rickover for a proposed candidate to lead INPO among other direct input to Vic Stello (NRC).
    A few years ago I was asked by UK and Canada organizations to help assess “Nuclear Culture” at their facilities. The “Thresher”, “TMI” and Rickover’s “Doing a Job” examples were/are great lessons.
    I could only add further comments to what you have already aptly stated!
    The Navy must have somehow institutionalized HGR’s “culture” based on their record as you have stated. The commercial NP record is spotty but overall the INPO/WANO metrics show a much better overall safety performance than pre-TMI which has certainly lowered risk.
    I really enjoy your “reminders”! Keep up the good work and stay safe.

  11. Philip Wagner

    Try being on a old Diesel Boat in Naples on April 10,’63 and having your damaged #1 periscope replaced by a destroyer tender crew that had never seen a periscope before and then going out two days later to test dive the boat. DBF!

    Where is the Savannah located now? I was aboard her in ~ ’80 for an NRC Project Manger inspection and discussions on the Bare Boat Charter that I approved.

    Thanks, Phil Wagner

  12. Stephen Fowler

    Will, I said “oh” when I opened your nuclear cafe article, loud enough for my wife to get worried.

    I served as a reactor operator on USS Barb, SSN596, before it was retrofitted with the Subsafe improvements, most of which centered on auxiliary seawater piping. Upgrades like those didn’t matter too much when passing over the Marianas (sp?) Trench.

    I was told back then that the accident was precipitated by a scram drill and until that loss, the main steam stops either automatically or by procedure were closed in the event of a scram. This was changed by the the time I served, which allowed a boat to try and drive to the surface using the steam still available to the turbine.

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