This is a document that grew in the writing to become a powerful assessment of what went wrong and why it went wrong with critically important contributions by engineers and those qualified to operate US nuclear submarines.

It has become far more than an analysis of acoustic detections of the disaster by HMCS Shelburne although that analysis provided the basis for the assessments about why the event occurred, assessments that rely on multiple independent lines of evidence, the bottom line for which is that there was no flooding before THRESHER collapsed at a depth of 2400-feet.

As was the case with the SCORPION book published in 2011, the writer has refused royalties. No one should seek to profit from such tragedies.

I would be very interested in reading this document for a number of reasons. Growing up in Portsmouth, NH, where the USS THRESHER was designed, built and home ported, its loss touched the community very greatly.
- Not only was the community very proud of that lead ship, many of us (including myself) had classmates who lost fathers on that ship
- Later in my 38+ years working for the USN as an Civil Servant, assets under my cognizance in the PMS395 Deep Submergence Systems Program Office, dove on and photographed USS THRESHER and USS SCORPION wreckage (in the CY 2000 time frame, after the 20,000 foot capable Advanced Tethered Vehicle (ATV) completed providing service to Dr. Robert Ballard and National Geographic, on diving on ships lost during the WWII Midway Battle, where ATV found and photographed USS YORKTOWN)
- I found Bruce Rule's discussion on the acoustic evidence he had access to and analyzed, fascinating, though I am not sure that I agree that the USS THRESHER was not flooding in its engineering spaces, prior to the collapse of its pressure hull. Photographs of its Auxiliary Machine Space-2 (AMS-2) pressure hull (later called AMR-2 in the 616 and later class hulls) that I have reviewed, indicates it was experiencing some high level of equalization to the outside water pressure, which would indicate flooding was indeed occurring. The AMR-2 pressure hull frames and shell plating pictures that I have seen, show little deformation due to external pressure loading. That was not the case with the Engine Room (ER) pressure hull frames and shell plating. The pictures that I have seen would indicate the watertight door in the bulkhead separating between AMS-2 and the ER had been shut and dogged.

The thing that has always troubled me was why was THRESHER so badly out of trim aft beside the flooding. I have performed numerous trim dives on submarines for reballasting purposes and also pierside compensation checks to provide a submarine's diving officer his variable ballast (VB) compensation for the submarine's first dive coming out of a major availability, when I was at NAVSHIPYD PTSMH NH and the ship sounds like it may have had an issue with its permanent ballast and/or its VB compensation. At test depth, the ship should have been compensated 10,000 to 20,000 lbs light, to be positively buoyant, forcing it to hold itself down with speed and planes.

I would be interested in comparing notes with Bruce as he may have some insight to that, and I have things to share with him that he may not be aware of.