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Contrary to My Expectations, Progress is Being Made on Why THRESHER Was Lost

A Dull Thud Cut Short 129 Lives on USS THRESHER (SSN 593) 58 Years Ago
Captain Jim Bryant, US Navy (Retired)

The nuclear-powered submarine USS THRESHER (SSN 593) was on a planned, routine deep dive to
test depth 220 miles east of Cape Cod, on the morning of April 10, 1963. At 9:18 and 24 seconds a
dull thud from a depth of 2,400 feet was heard over the underwater telephone. One of the anxious
naval officers on the bridge of the escort ship, submarine rescue vessel USS SKYLARK (ASR 20),
recognized this sound from his WWII experience as collapsing compartments on a sinking ship.

THRESHER’s hull was obliterated with a force equivalent to 22,500 pounds of TNT in 0.047 seconds,
mercifully for the men on board too fast to be cognitively recognized. The sound of the collapse was
made up of frequencies mostly below 50 Hertz, which to the human ear sounded like a dull thud.
These frequencies were recorded by hydrophones as far away as 1,300 miles in waters in the southern
Caribbean Sea near Antigua.

THRESHER was needed to counter the rapidly growing Soviet submarine force including their own nuclear
submarines. THRESHER was the most advanced submarine in the world and the U.S. Navy’s most effective
Anti-Submarine Warfare platform. It was fast, silent and had a revolutionary sonar; its maximum operating
depth or test depth was reported as nearly twice that of previous submarine classes.

The Navy’s report of this disaster shows the root cause was not appreciating the dangers of almost doubling
the test depth. The fabrication, repair, and quality assurance procedures were not improved fast enough or
applied with enough rigor to prevent this disaster. Before September 2020, only 19 pages were made public
of the 1,700 pages of testimony from the Court of Naval Officers assembled to study this tragic loss. With the
Navy’s continuing release of THRESHER documents resulting from a court order to incrementally release this
information, almost 1,500 pages are now available for review on the Secretary of the Navy’s Reading Room
website: https://www.secnav.navy.mil/foia/readingroom/SitePages/Home.aspx

Led by Captain Jim Bryant, US Navy (Retired), a team has studied the loss of THRESHER since 2017. On 13
March 2021, members of Bryant’s team participated in a webinar hosted by the Naval Historical Foundation
on what was learned from this newly declassified information, which can be viewed at this link:
https://youtu.be/4wJQUDOhu-U

This webinar discusses that Navy coverups were unlikely and investigates some of the many factors that
contributed to THRESHER’s loss including:

· Deep dive test procedure was not appropriate
· Admiral Rickover acknowledges an emergency propulsion procedure that might have saved THRESHER,
but was not approved
· Navy’s lack of training Infrastructure, supporting documentation and operational training
· Why pumping to sea and the high pressure air of Main Ballast Tank Blow System failed to surface THRESHER
· Details of the fatal deep dive and what may have happened
· Inadequate testing of critical piping joints

The next release of information in April should contain the testimony of the Chief of Naval Personnel, who
was at odds with Admiral Rickover over selection of officers for his Nuclear Propulsion Program. In May we
should see the first of the exhibits used as evidence in the official Navy THRESHER Report.

Jim Bryant

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