Thresher SSN-593 - History

Thresher SSN-593 - History

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Thresher II
(SSN-593: dp. 3,700 (surf.), 4,300 (subm.), 1. 278'6";
b. 31'8"; s. 20+ k.; cpl. 100; a. 4 tt.; cl. Thresher)

The second Thresher (SSN-593) was laid down on 28 May 1958 by the Portsmouth (N.H.) Naval Shipyard; launched on 9 July 1960; sponsored by Mrs. Frederick B. Warder; and commissioned on 3 August 1961, Comdr. Dean W. Axene in command.

Following trials, the nuclear attack submarine took part in Nuclear Submarine Exercise (NUSUBEX) 3-61 off the northeastern coast of the United States from 18 to 24 September

On 18 October; the submarine headed south along the east coast. After calling at San Juan, Puerto Rico, she conducted further trials and test-fired her torpedo system before returning to Portsmouth on 29 November. The ship remained in port through the end of the year and spent the first two months of 1962 evaluating her sonar system and her Submarine Rocket (SUBROC) system. In March, the submarine participated in NUSUBEX 2-62, an exercise designed to improve the tactical capabilities of nuclear submarines, and in antisubmarine warfare training with Task Group ALPHA.

Off Charleston, the ship undertook operations observed by the Naval Antisubmarine Warfare Council, before she returned briefly to New England waters from whence she proceeded to Florida for SUBROC tests. However, while mooring at Port Canaveral, the submarine was accidentally struck by a tug which damaged one of her ballast tanks. After repairs at Groton, Conn., by the Electric Boat Company, the ship returned south for more tests and trials off Key West. Thresher then returned northward and remained in dockyard hands through the early spring of 1963.

In company with Skylark (ASR-20), Thresher put to sea on 10 April 1963 for deep-diving exercises. In addition to her 16 officers and 96 enlisted men, the submarine carried 17 civilian technicians to observe her performance during the deep-diving tests.

Fifteen minutes after reaching her assigned test depth, the submarine communicated with Skylark by underwater telephone, apprising the submarine rescue ship of difficulties. Garbled transmissions indicated that —far below the surface-things were going wrong. Suddenly, listeners in Skylark heard a noise "like air rushing into an air tank"—then, silence.

Efforts to reestablish contact with Thresher failed, and a search group was formed in an attempt to locate the submarine. Rescue ship Recovery (ASR-43) subsequently recovered bits of debris, including gloves and bits of internal insulation. Photographs taken by bathyscaph Trieste proved that the submarine had broken up, taking all hands on board to their deaths in 1,400 fathoms of water, some 220 miles east of Boston.

Thresher was officially declared lost in April 1963.

The Loss of USS THRESHER (SSN-593)

Fifty-one years ago today, on the morning of 10 April 1963, USS THRESHER (SSN-593), less than two years old and the lead boat in a new class of nuclear-powered, fast-attack submarines, began deep-diving tests about 200 miles to the east of Cape Cod, MA. The submarine-rescue ship USS SKYLARK (ASR-20) stood by overhead. At 0903 SKYLARK received a garbled transmission over the underwater telephone: THRESHER reported “Experiencing minor difficulties. …Have positive up angle…attempting to blow.” But THRESHER and the 129 men she carried—including 17 civilians—never returned to the surface.

The remains of the sub, broken up into six major sections, were eventually found scattered over a large area in more than eight thousand feet of water. After a thorough examination of photographs, objects recovered from the bottom, and records of the sub’s construction and maintenance, a Court of Inquiry concluded that THRESHER’s troubles likely began with the joints in her saltwater piping system, many of which had been brazed rather than welded. (Welding involves the heating to melting and direct joining of two pieces of metal, whereas brazing uses another material, one that melts at a lower temperature, to “glue” two pieces of metal together. In THRESHER’s case, a silver alloy was used as “glue.”) It has been theorized that at least one of those joints failed, permitting seawater to leak into the boat and short out an electrical panel which in turn triggered a scram, or shutdown, of the reactor. Without a means of propulsion, THRESHER, gaining weight as water flooded in through the failed joint, began to sink.

THRESHER’s crew then tried to blow their main ballast tanks to propel the boat to the surface. They may have been hampered in their efforts by moisture freezing in strainers installed in high-pressure air-reducing valves in the blow system. Without that air there was no way to clear the water from the ballast tanks without the reactor there was no way to fight the weight of the water and drive the boat to the surface.

Onboard SKYLARK, there was initially little cause for alarm. The two vessels met up at 0635 and THRESHER indicated that she was beginning her deep-dive test at 0747. As planned, the boat checked in with SKYLARK every fifteen minutes. All was well until just after 0900 when THRESHER sent a muddled message: “Have positive up angle,” LT(jg) James Watson, SKYLARK’s navigator, recalls hearing. “Attempting to blow up [execute an emergency blow].” But transmissions over the underwater telephone were often difficult to understand and the C.O. did not sound panicked. SKYLARK cleared the sub to surface at 0914. There was no reply. A minute later SKYLARK asked the sub to report her course and position relative to the rescue ship. Again, silence. The C.O. then asked several times, “Are you in control?” Nothing came back until a few moments later when another garbled message came through. The SKYLARK crew could discern only two words: “test depth.” Watson would later testify that he believed the word preceding those two was “exceeding.”

“What then did you hear?” the questioner asked.

“We heard sounds that are familiar to me, from having seen ships blown up by torpedoes in World War II—the sound of a ship breaking up—like a compartment collapsing…a muted, dull thud,” Watson replied. SKYLARK’s sonar operators would liken the sound to that of “air rushing into an air tank.” Nothing more was heard from THRESHER. SKYLARK’s crew dropped several small grenades into the water starting at 1058 the sound of their explosions was supposed to indicate to the boat that the surface vessel had lost contact with her and wanted her to either check in via the telephone or surface. But she never called or came back up.

This first loss of a nuclear-powered submarine devastated the naval community, including Groton, CT, where the sub was home ported, and Portsmouth, NH, where the she was built. The men who went down on THRESHER did not die in vain. The tragedy prompted the navy to reexamine deep-diving submarine design, institute a quality-assurance program known as SUBSAFE which “provides a maximum reasonable assurance of the integrity of submarine design, systems and materials via Design Review, Shipboard System Testing and Objective Quality Evidence (OQE) that all materials and components meet drawing and specification requirements.” Operating procedures for submarine reactors were changed to allow use of heat energy stored in plant components to provide propulsion while the reactor plant was restarted following an emergency shutdown.

It is impossible to know how many lives have been saved by the changes that were made after THRESHER’s loss, just as it is impossible to know exactly what happened on board the boat that spring morning. But it is safe to say that submariners are safer now because of the sacrifice that was made by their shipmates half a century ago.

USS Thresher SSN-593

On the morning of April the 10th Thresher, commanded by Lieutenant Commander John Wesley Harvey, began post-overhaul trials.

Accompanied by the submarine rescue ship Skylark, she sailed to an area some 190 nmi east of Cape Cod, Massachusetts, and on the morning of 10 April started deep-diving tests. As Thresher neared her test depth, Skylark received garbled communications over underwater telephone indicating “… minor difficulties, have positive up-angle, attempting to blow.” When Skylark received no further communication, surface observers gradually realized Thresher had sunk. Publicly it took some days to announce that all 129 officers, crewmen, and military and civilian technicians aboard were presumed dead.

After an extensive underwater search using the bathyscaphe Trieste, oceanographic ship Mizar and other ships, Thresher’s remains were located on the sea floor, some 8,400 ft below the surface, in six major sections.

The majority of the debris had spread over an area of about 160,000 sq yd. The major sections were the sail, sonar dome, bow section, engineering spaces section, operations spaces section, and the stern planes.

Timeline of the Thresher disaster:

07:47 Thresher begins its descent to the test depth of 1,000 ft.

07:52 Thresher levels off at 400 ft, contacts the surface, and the crew inspects the ship for leaks. None are found.

08:09 Commander Harvey reports reaching half the test depth.

08:25 Thresher reaches 1,000 ft.

09:02 Thresher is cruising at just a few knots (subs normally moved slowly and cautiously at great depths, lest a sudden jam of the diving planes send the ship below test depth in a matter of seconds.) The boat is descending in slow circles, and announces to Skylark she is turning to “Corpen [course] 090.” At this point, transmission quality from Thresher begins to noticeably degrade, possibly as a result of thermoclines.

09:09 It is believed a brazed pipe-joint ruptures in the engine room. The crew would have attempted to stop the leak at the same time, the engine room would be filling with a cloud of mist. Under the circumstances, Commander Harvey’s likely decision would have been to order full speed, full rise on the fairwater planes, and blowing main ballast in order to surface. The pressurized air rapidly expanding in the pipes cools down, condensing moisture and depositing it on strainers installed in the system to protect the moving parts of the valves in only a few seconds the moisture freezes, clogging the strainers and blocking the air flow, halting the effort to blow ballast. Water leaking from the broken pipe most likely causes short circuits leading to an automatic shutdown of the ship’s reactor, causing a loss of propulsion. The logical action at this point would have been for Harvey to order propulsion shifted to a battery-powered backup system. As soon as the flooding was contained, the engine room crew would have begun to restart the reactor, an operation that would be expected to take at least 7 minutes.

09:12 Skylark pages Thresher on the underwater telephone: “Gertrude check, K [over].” With no immediate response (although Skylark is still unaware of the conditions aboard Thresher), the signal “K” is repeated twice.

09:13 Harvey reports status via underwater telephone. The transmission is garbled, though some words are recognizable: “[We are] experiencing minor difficulty, have positive up-angle, attempting to blow.” The submarine, growing heavier from water flooding the engine room, continues its descent, probably tail-first. Another attempt to empty the ballast tanks is performed, again failing due to the formation of ice. Officers on Skylark could hear the hiss of compressed air over the loudspeaker at this point.

09:14 Skylark acknowledges with a brisk, “Roger, out,” awaiting further updates from the SSN. A follow-up message, “No contacts in area,” is sent to reassure Thresher she can surface quickly, without fear of collision, if required.

09:15 Skylark queries Thresher about her intentions: “My course 270 degrees. Interrogative range and bearing from you.” There is no response, and Skylark’s captain, Lieutenant Commander Hecker, sends his own gertrude message to the submarine, “Are you in control?”

09:16 Skylark picks up a garbled transmission from Thresher, transcribed in the ship’s log as � N.” [The meaning of this message is unclear, and was not discussed at the enquiry it may have indicated the submarine’s depth and course, or it may have referred to a Navy “event number” (1000 indicating loss of submarine), with the “N” signifying a negative response to the query from Skylark, “Are you in control?”]

09:17 A second transmission is received, with the partially recognizable phrase “exceeding test depth….” The leak from the broken pipe grows with increased pressure.

09:20 Skylark continues to page Thresher, repeatedly calling for a radio check, a smoke bomb, or some other indication of the boat’s condition.

11:04 Skylark attempts to transmit a message to COMSUBLANT (Commander, Submarines, Atlantic Fleet): “Unable to communicate with Thresher since 0917R. Have been calling by UQC voice and CW, QHB, CW every minute. Explosive signals every 10 minutes with no success. Last transmission received was garbled. Indicated Thresher was approaching test depth…. Conducting expanding search.” Radio problems meant that COMSUBLANT did not receive and respond to this message until 12:45. Hecker initiated “Event SUBMISS [loss of a submarine]” procedures at 11:21, and continued to repeatedly hail Thresher until after 17:00.

On 11 April, at a news conference at 10:30, the Navy officially declared the ship as lost.

USS Thresher SSN-593 USS Thresher SSN-593 USS Thresher SSN-593 USS Thresher SSN-593 USS Thresher SSN-593 USS Thresher SSN-593 USS Thresher SSN-593 USS Thresher SSN-593 USS Thresher SSN-593 USS Thresher SSN-593 USS Thresher SSN-593 USS Thresher SSN-593 USS Thresher SSN-593 USS Thresher SSN-593 USS Thresher SSN-593 USS Thresher SSN-593


This section lists the names and designations that the ship had during its lifetime. The list is in chronological order.

    Thresher Class Attack Submarine
    Keel Laid 28 May 1958 - Launched 9 July 1960

SUNK as a result of a casualty during diving tests
in 1,400 fathoms of water, approximately 220 miles east of Boston, MA.
16 officers, 96 enlisted men and 17 civilian technicians remain on Eternal Patrol

Naval Covers

This section lists active links to the pages displaying covers associated with the ship. There should be a separate set of pages for each incarnation of the ship (ie, for each entry in the "Ship Name and Designation History" section). Covers should be presented in chronological order (or as best as can be determined).

Since a ship may have many covers, they may be split among many pages so it doesn't take forever for the pages to load. Each page link should be accompanied by a date range for covers on that page.


This section lists examples of the postmarks used by the ship. There should be a separate set of postmarks for each incarnation of the ship (ie, for each entry in the "Ship Name and Designation History" section). Within each set, the postmarks should be listed in order of their classification type. If more than one postmark has the same classification, then they should be further sorted by date of earliest known usage.

A postmark should not be included unless accompanied by a close-up image and/or an image of a cover showing that postmark. Date ranges MUST be based ONLY ON COVERS IN THE MUSEUM and are expected to change as more covers are added.
>>> If you have a better example for any of the postmarks, please feel free to replace the existing example.

U.S.S. Thresher

A contributor in Chicopee, Massachusetts has a stack of technical drawings and engineering documents he found in his late great-uncle&rsquos basement some years ago.

A few of the documents bear the numbers and letters SSN-593.

This appellation belonged to the nuclear submarine USS Thresher, an attack class vessel that had been the pride of the U.S. Navy during the Cold War.

On April 10th, 1963, the Thresher was undergoing deep sea trials when, along with its nuclear reactor, the vessel sank with the loss of all hands 220 miles off the coast of Massachusetts.

How could our contributor's great-uncle have been in possession of documents linked to one of the most secret weapons in the U.S. Cold War arsenal?

History Detectives explores one of the most traumatic events in U.S. Naval history.

Season 5, Episode 10

Gwen Wright Location:
New York, New Jersey and Massachusetts

Declassified documents shed new light on notorious sinking of USS Thresher

A long time ago, when I was sitting in the 3rd grade, next to the son of the Thresher’s XO at a grade school on Pease AFB, near Portsmouth, NH. The school was a unified school for dependents of military families, USAF and Navy. Of course, none of us were aware of this tragedy until we got home. A long time ago, and something I will never forget.

At 8 a.m. on April 9, 1963, USS Thresher (SSN-593), the lead boat in its class of nuclear-powered attack submarines, left port at Kittery, Maine, for a series of dive tests in the deep ocean 350 kilometres east of Cape Cod, Massachusetts.

Some 25 hours later, while Thresher was nearing test depth during its first deep-dive trials after a nine-month refit, USS Skylark, the submarine rescue ship that was on station at the time, received a garbled message via underwater telephone.

“Minor difficulties, have positive up-angle, attempting to blow,” came the call, and then a final, even more garbled message distinguished by the number “900” at 9:17 a.m.

Sonar technicians reported hearing mysterious “air rushing” noises. They were the last sounds Skylark heard from the 85-metre vessel, equipped with the most advanced weapons and sonar systems available and considered the fastest and quietest submarine of its day.

By mid-afternoon, 15 navy ships were headed to the search area. At 6:30 p.m., the commander of Submarine Force Atlantic ordered Portsmouth Naval Shipyard to notify families that Thresher was missing. They were to start with Irene Harvey, wife of the boat’s skipper, Lieutenant-Commander John Wesley Harvey.

By next morning, all hope was abandoned. The chief of naval operations, Admiral George W. Anderson Jr., called a Pentagon news conference and announced that Thresher had been lost with all hands—16 officers, 96 enlisted, and 17 civilian contractors.

President John F. Kennedy ordered flags lowered to half-staff for four days. It remains the second-deadliest submarine disaster on record, after the French boat Surcouf collided with a freighter in the Caribbean one night in February 1942 and sank with all 130 crew.

A U.S. Navy search vessel found the shattered Thresher 14 months later, lying in five major pieces on the sea floor, 2.6 kilometres beneath the surface. The debris field covered some 134,000 square metres (33 acres).

Based on photographs, artifacts and an evaluation of Thresher’s design and operational history, a court of inquiry officially concluded that a saltwater piping system joint that relied heavily on silver brazing instead of welding had failed.

Crews were unable to reach equipment to stop the flooding in time and the ballast tanks failed to work properly.

The incoming water likely shorted out the boat’s electrical systems, it said, shutting down the reactor and causing a critical loss of propulsion, which the sub would have needed to surface. It wasn’t the first time the joints—made by pouring a melted, silver-based filler alloy into the link—had been an issue.

The navy investigation remained classified for decades, spawning a growing list of theories and scepticism surrounding what happened. That is until James Bryant, who commanded three Thresher-class submarines before he retired, sued in 2019 to get the files released. Last year, a judge ordered 3,600 pages declassified. They’ve been coming out in dribs and drabs ever since.

Experts say the latest batch, released in mid-March, proves the U.S. Navy was not covering anything up. The accident, like most disasters, was the result of a series of foul-ups that included but were not limited to a joint failure.

The documents suggest the submarine and its crew were the victims of a deadly arms race, over-confidence in the developing systems aboard their boat, and inadequate training in how to use them.

It was six months after the Cuban Missile Crisis and tensions were high. The Soviet Union had launched its first nuclear-powered submarine in 1958. There was a pressing need for larger, faster submarines like Thresher that were capable of diving to almost twice the depth of their Second World War predecessors.

The first Polaris-class ballistic-missile submarines were entering the fleet, requiring two crews and putting more pressure on the training and certification pipelines.

Historian Norman Friedman, who has written extensively on post-Second World War submarines, told the U.S. Naval Institute News that “under the circumstances, people took chances.”

He said conventional navy thinking at the time was that nuclear-powered systems were sufficiently backed up to ensure propulsion and surfacing capabilities in an emergency. They never considered the possibility nuclear subs could lose power.

The Soviet threat and sense of urgency to counter it was prevalent among the 1960s-era investigators. The U.S. Navy had 28 nuclear-powered submarines in the fleet and 36 more planned when Thresher sank.

The navy of the day underestimated the risks and didn’t give adequate consideration to how to rescue crews from these new depths, according to Stephen Walsh, who worked in the Submarine Safety Program, known as SUBSAFE, that grew out of the disaster and the 1968 sinking of USS Scorpion.

The watch in charge had taken 20 minutes to isolate a simulated leak in the auxiliary seawater system during a dockside simulation of flooding in Thresher’s engine room before sailing. At test depth with the reactor shut down, the boat would not have had 20 minutes to recover. Even after isolating a short circuit in the reactor controls, it would have taken nearly 10 minutes to restart the plant.

It was believed at the time that Thresher imploded at between 400 and 610 metres below the surface. Bruce Rule, an acoustic data expert, analyzed the data in 2013 and concluded Thresher imploded at 9:18:24 at a depth of 730 metres—120 metres below her predicted collapse depth.

The implosion took 0.1 seconds. Some might have expected it, but the crew would never have known it happened.

“When you read the court of inquiry [you realize] how complicated the machinery is,” Friedman said, adding that to prevent disaster, crew “have to know where to go instinctively” when something starts to go wrong.

Training and engineering practices aboard nuclear subs were revamped after the Thresher and Scorpion sinkings, the latter with the loss of 99 crew. SUBSAFE was formed to oversee submarine design and construction. It is credited with the fact the U.S. Navy hasn’t lost a submarine in more than half a century.

Four sets of Thresher documents have been released since September 2020, along with two additional sets of related reports Bryant requested. Period testimony from the chief of naval personnel is still to come.

“Thresher was never decommissioned and remains on “eternal patrol.””

Bryant and other experts say the documents’ release is good for the U.S. Navy, putting to rest suspicions of a coverup and confirming that navy brass sought only to prevent operational details from falling into the hands of U.S. adversaries.

Now that the material is declassified, submarine safety instructors “can take it home, read it and take it into the classroom,” said Bryant, adding that graduate engineering students can also use it to better understand how to prevent future accidents from becoming disasters like the one that sank Thresher.

As is navy tradition, Thresher was never decommissioned and remains on “eternal patrol.” The designation derives from the fact that submarine patrols begin at departure from port and end on their return. Hence, the patrol for a sub that sinks never ends.

The navy, meanwhile, continues to monitor environmental conditions surrounding the site and reports that Thresher’s nuclear fuel remains intact.

Fifty-Seven Years Later: America’s Worst Nuclear Submarine Disaster

Fifty-seven years ago today, America suffered its first, and in terms of fatalities its worst, loss of a nuclear-powered submarine. Yet, much of the information about that disaster and the Navy’s subsequent investigation has remained outside of public view. That may change this year.

On April 10, 1963, the nuclear-powered fast attack submarine USS Thresher (SSN 593), the first of a new class of submarine, was lost at sea when it sank while conducting a deep dive test some 220 miles east of Cape Cod. All 129 crew members and civilians on the Thresher perished with her. Later that day, the commander in chief of the United States Atlantic Fleet ordered a court of inquiry to investigate Thresher’s sinking. The court of inquiry issued its report in June 1963 but was unable to determine what caused Thresher to sink. The court of inquiry did opine, however, that a flooding casualty in the Thresher’s engine room was the most probable cause of Thresher’s sinking. The court of inquiry encouraged further study.

Over a half-century later, very little of the record of the court of inquiry has been publicly released even though the Navy undertook a declassification review of the records in April 1998 with a stated purpose to declassify and release information from these records to the public “whenever possible.” That review came to naught when in February 2012, after up to 75 percent of the records had been declassified, the Navy changed course, deciding it would not make a public release of the records. Instead, the Navy said the records were “available for public release through” a Freedom of Information Act (FOIA) request.

Last year, retired Navy Captain James Bryant, who had commanded a Thresher-class submarine in the 1980s, learned that Arlington National Cemetery planned a September 2019 dedication ceremony for a memorial to the 129 lives lost with the Thresher. As a result, Bryant, who now investigates, lectures and writes about the loss of the Thresher and the accuracy of the investigating court of inquiry, submitted a FOIA request in April 2019 to the Navy for records about the loss of the Thresher, specifically including the record of the court of inquiry. He requested expedited processing, hoping the Navy might release the records before the Thresher memorial’s dedication ceremony. In July 2019, after exhausting his administrative appeals, Bryant filed a FOIA lawsuit.

In February this year, Judge Trevor N. McFadden of the U.S. District Court for the District of Columbia ordered the Navy to review 300 pages of documents a month starting April 30 and by the end of every month thereafter, and to begin rolling productions of documents starting on or before May 15 and every month thereafter.

Therefore, during this 57th anniversary year of the Thresher’s sinking, the American public, including the families of the 129 men who lost their lives, may finally begin to see the Navy’s documents on the loss of the Thresher and the record of the court of inquiry that investigated that loss. How much of the information in these documents the Navy will choose to release is a separate matter. The Navy may continue to keep as much information as possible from the public as allowed by law, may use its discretionary authority to release as much information as possible to the public, or may take an approach somewhere in between. What one can say with some degree of confidence, however, is that some amount of these records will be released in full or with redactions before the 58th anniversary of the loss of the USS Thresher.

USS Thresher (SSN-593)

Figure 1: USS Thresher (SSN-593) bow-on view, taken at sea on 24 July 1961. Official US Navy Photograph, from the collections of the NHHC. Click on photograph for larger image.

Figure 2: USS Thresher (SSN-593) starboard bow view, taken at sea on 24 July 1961. Official U.S. Navy Photograph, from the collections of the NHHC. Click on photograph for larger image.

Figure 3: USS Thresher (SSN-593) stern-on view, taken at sea on 24 July 1961. Note upper rudder in the foreground, with draft markings painted on its side and navigation light at its top. Official US Navy Photograph, from the collections of the NHHC. Click on photograph for larger image.

Figure 4: USS Thresher (SSN-593) starboard broadside view, taken while the submarine was underway on 30 April 1961. Photographed by J.L. Snell. Official US Navy Photograph, from the collections of the NHHC. Click on photograph for larger image.

Figure 5: USS Thresher (SSN-593) port broadside view, taken while the submarine was underway on 30 April 1961. Photographed by J.L. Snell. Official US Navy Photograph, from the collections of the NHHC. Click on photograph for larger image.

Figure 6: USS Thresher (SSN-593) port broadside view, taken while the submarine was underway with water surging over her bow, 30 April 1961. Photographed by J.L. Snell. Official US Navy Photograph, from the collections of the NHHC. Click on photograph for larger image.

Figure 7: Loss of USS Thresher (SSN-593), April 1963. Navy ships circle in the vicinity of the site of Thresher's sinking, 15 April 1963, five days after her loss. Ships are (left to right): USS Thomas Jefferson (SSBN-618) USS Sunbird (ASR-15) USS Warrington (DD-843), group flagship and USS Redfin (SS-272). Photographed by PHCS Parker. Official US Navy Photograph, from the collections of the NHHC. Click on photograph for larger image.

Figure 8: US Navy Bathyscaphe Trieste (1958-1963) under tow and en route to a deep-water dive in the Pacific, 15 September 1959. She is flying both the United States and Swiss flags. Trieste was used in the search for the wreck of Thresher. US NHHC Photograph. Click on photograph for larger image.

Figure 9: U.S. Navy Bathyscaphe Trieste (1958-1963) is hoisted out of the water in a tropical port, circa 1958-1959, soon after her purchase by the Navy. Photograph was released by the US Navy Electronics Laboratory, San Diego, California. Trieste was used in the search for the wreck of Thresher. US NHHC Photograph. Click on photograph for larger image.

Figure 10: USNS Mizar (T-AGOR-11) photographed on a winter day in the middle or later 1960s. Mizar was used in the search for the wreck of Thresher. US NHHC Photograph. Click on photograph for larger image.

Figure 11: USNS Mizar (T-AGOR-11) , which was used in the search for the wreck of Thresher. Here she is photographed circa 1970, by the US Naval Research Laboratory, for which the ship was operated by the Military Sealift Command. The original caption, received with this photograph under date of October 1970, states: ". The ship has been used to investigate the ocean depths and to locate lost ships and, most recently, to find the site of the scuttled Liberty Ship Le Baron Russell Briggs which sank during August 1970 in 16,000 feet of water about 230 miles off the coast of Florida with 418 concrete and steel coffins of nerve-gas rockets aboard." Official US Navy Photograph, from the collections of the NHHC. Click on photograph for larger image.

Figure 12: Loss of USS Thresher (SSN-593), April 1963 . "Debris on the ocean floor 8,400 feet below the surface may be a clue to the final resting place of the nuclear submarine USS Thresher. Taken last week by an underwater camera system operated by the oceanographic research vessel Atlantis II, these photographs show scattered bits of unidentified debris. The round objects are sea urchins which may range in size from four to twelve inches in diameter. The Navy states that the photographs in themselves are not conclusive evidence of the location of the missing submarine which sank on April 10, 1963, 220 miles east of Cape Cod. Ships of the searching force are continuing a minute search of the area with underwater cameras, sonar and other detection devices." Quoted from the original caption released with this photograph on 22 May 1963. Official US Navy Photograph, from the collections of the NHHC. Click on photograph for larger image.

Figure 13: Wreck of USS Thresher (SSN-593) . "Starboard side of the USS Thresher sail with portions of the hull number '593' visible." Photographed from a deep-sea vehicle deployed from USNS Mizar (T-AGOR-11). The original photograph bears the date October 1964. Quoted text is from the caption released with that print. Official US Navy Photograph, from the collections of the NHHC. Click on photograph for larger image.

Figure 14: Wreck of USS Thresher (SSN-593) . Overhead view of Thresher's upper rudder, photographed from a deep-sea vehicle deployed from USNS Mizar (T-AGOR-11). The view shows draft markings on the rudder side and a navigation light at its top. The original photograph bears the date October 1964. Thresher was lost on 10 April 1963. Official US Navy Photograph, from the collections of the NHHC. Click on photograph for larger image.

Figure 15: Wreck of USS Thresher (SSN-593) . "Sonar Dome -- A section of a sonar dome from the bow of a Thresher class submarine photographed August 24 during the second series of dives by the bathyscaph Trieste. The bathyscaph has completed 10 dives some 220 miles east of Cape Cod where the nuclear-powered submarine Thresher sank April 10." The original view, from whose caption the quoted text is taken, was released on 5 September 1963. Official US Navy Photograph, from the collections of the NHHC. Click on photograph for larger image.

Figure 16: Wreck of USS Thresher (SSN-593) . "Sonar Dome -- An external portion of a sonar dome used exclusively in Thresher class submarines was photographed by the bathyscaph Trieste August 24 during the second series of dives in the area where the nuclear-powered submarine Thresher sank April 10." The original view, from whose caption the quoted text is taken, was released on 5 September 1963. Official US Navy Photograph, from the collections of the NHHC. Click on photograph for larger image.

Figure 17: Lieutenant John Wesley Harvey, USN . Portrait photograph taken 14 November 1955 by Farber. Lieutenant Commander Harvey took command of the nuclear-powered attack submarine Thresher (SSN-593) in January 1963,while she was in the shipyard for overhaul. He took his "boat" to sea for the first time for post-overhaul trials. On 10 April 1963, Lieutenant Commander John W. Harvey lost his life when Thresher accidently sank during diving tests. Official US Navy Photograph, from the collections of the Naval Historical Center. Click on photograph for larger image.

Figure 18: Insignia: USS Thresher (SSN-593) . Emblem adopted in 1960 and received in October of that year. It was accompanied with this description: "The fish depicted in the subject insignia is a THRESHER shark, which is characterized by a tail that is approximately one-half of its total length. The THRESHER shark reportedly attacks its prey by flailing the long tail. The horizontal lines signify the deep diving capability of THRESHER. The circles represent her sonar capability. The motto, 'Vis Tacita', describes the overall characteristics of the ship, 'Silent strength'." US Naval Historical Center Photograph. Click on photograph for larger image.

Named after a type of shark, the 3,700-ton USS Thresher (SSN-593) was a lead ship in a class of nuclear-powered attack submarines that was built by the Portsmouth Naval Shipyard at Kittery, Maine, and was commissioned on 3 August 1961. The ship was approximately 278 feet long and 31 feet wide, had a top speed of more than 20 knots, and had a crew of 112 officers and men. Thresher was armed with four torpedo tubes.

After being commissioned, Thresher conducted lengthy trials in the western Atlantic and Caribbean oceans in 1961 and 1962. She completed a thorough evaluation of her many new technological features and weapons. The ship seemed to operate normally and without any major complications. Once these tests were completed, Thresher returned to her builders for an overhaul.

After her overhaul was completed, Thresher sailed out to sea on 10 April 1963 for post-overhaul trials. She was accompanied by the submarine rescue ship USS Skylark (ASR-20) and moved to a location roughly 220 miles east of Cape Cod, Massachusetts. Thresher then initiated deep-diving tests as part of her shakedown exercises. As the ship dove deep into the Atlantic, garbled communications were received by Skylark, indicating that there was trouble on board the submarine. Suddenly, the radio operators on board Skylark heard a noise “like air rushing into an air tank” and then silence. Those garbled transmissions were the last anyone ever heard from Thresher as well as the 112 officers, crewmen, and 17 civilian technicians that were on board the ship. Something had gone terribly wrong.

All efforts by Skylark to re-establish contact with Thresher failed. Five days after the loss of Thresher, a small search group was formed, which included USS Thomas Jefferson (SSBN-618), USS Sunbird (ASR-15), USS Warrington (DD-843) (the group’s flagship), and USS Redfin (SS-272). But nothing was found. The US Navy then called in reinforcements to search for the lost submarine. The remarkable bathyscaphe Trieste was brought into action along with the oceanographic ship Mizar (T-AK-272). A bathyscaphe is a small, modified submarine used for deep-sea exploration. It usually has a spherical observation chamber designed to hold two people placed underneath the ship’s main buoyancy chamber. Trieste was designed to go deep into the ocean without being literally crushed by the water above it. In January 1960, Trieste dove a record 35,791 feet into the Marianas Trench in the western Pacific Ocean, reaching the deepest part of any ocean on earth. Mizar was an oceanographic research ship with a deep-submergence support capability. Her specialty was locating and examining the wrecks of lost ships.

Kittery Maine USS Thresher (SSN 593) Memorial

Forever on patrol, never to be forgotten , There are 129 names inscribed.

Forever on patrol, never to be forgotten
There are 129 names inscribed.

Topics and series. This historical marker memorial is listed in these topic lists: Disasters &bull Waterways & Vessels. In addition, it is included in the Still On Patrol series list. A significant historical date for this entry is April 10, 1963.

Location. 43° 6.065′ N, 70° 44.526′ W. Marker is in Kittery, Maine, in York County. Marker is at the intersection of Rogers Road and Shepards Cove Road, on the right on Rogers Road. Marker is across the street from the Kittery Town Hall. Touch for map. Marker is in this post office area: Kittery ME 03904, United States of America. Touch for directions.

Other nearby markers. At least 8 other markers are within 2 miles of this marker, measured as the crow flies. Kittery Maine War Memorial (about 400 feet away, measured in a direct line) Historic Rice Public Library (approx. one mile away) Sloop Ranger Memorial (approx. 1.1 miles away) USMC Memorial Marker

From the report

U.S. and Soviet Submarine Programs

During the very early sixties, the U.S. Navy introduced not only the hydrodynamically advanced Skipjack, but the Navy’s smallest nuclear powered ASW submarine, the 2,300-ton prototype Tullibee (SSN 597), carrying the first version of the BQQ-2 sonar system. The improvement in passive detection which this represented was incorporated in the larger Thresher (SSN 593) class which followed immediately.

Redacted portion of the unclassified Cross Report that included the test depth of Thresher during its 1963 loss.

From a strategic point of view, the five Fleet Ballistic Missile submarines of the George Washington class (SSBN 598) were followed immediately by the improved Ethan Allen (SSBN 608) class. The success of the nationally oriented, strategic deterrent Polaris program led to the first U.S . SSBNs going on patrol by mid-1960. The need for Polaris submarines in the North Atlantic and Mediterranean, where their relatively short range A-1 missiles could be effective, delayed Polaris deployment in the Pacific until the Daniel Boone (SSBN 628) made her first patrol in December 1964.

While the United States had terminated its cruise missile submarine construction programs along with the Regulus II missile development, the Soviets elected to continue development in this area. Early Soviet designs were very short range–under then current U.S. intelligence projections. The cruise missile carried by the Juliett and Echo classes, for example, was able to reach only 220 miles, while the range of the SS-N-4 ballistic missiles was a mere 350 nautical miles, this being extended in 1963 with the introduction of the 700 mile SS-N-5. This limitation forced Soviet operation close to the United States, increasing emphasis on the close-in SOSUS shallow water system then under development. In short, Soviet missile technology during this period lagged behind that of the U.S., all Russian missile systems requiring surface launch while the Polaris A-1 missiles, able to reach 1,300 nautical miles, could be fired from a submerged submarine.

USNI News has uploaded two versions of the document. One is the original scan of the pages provided by the Navy, the second is a word-searchable document. Processing the searchable document has left some difficult to read pages blank which can be seen in the original version.

Download the original version here.
Download the word-searchable document here.

Watch the video: USS Thresher SSN-593 documentary (May 2022).