USS Thresher (SSN-593)
.jpg) The Thresher 1961 on the water surface |
|
| Overview | |
|---|---|
| Shipyard | |
| Order | January 15, 1958 |
| Keel laying | May 28, 1958 |
| Launch | July 9, 1960 |
| 1. Period of service |
|
| Commissioning | 3rd August 1961 |
| Whereabouts | Sunk on April 10, 1963 |
| Technical specifications | |
| displacement |
3770 tons submerged |
| length |
84.7 meters |
| width |
9.8 meters |
| Draft |
8.8 meters |
| crew |
16 officers, 96 men |
| drive |
1 × S5W pressurized water reactor, one shaft |
| speed |
30 knots |
| Armament |
4 × torpedo tubes 533 mm |
The USS Thresher (SSN-593) was a nuclear powered submarine of the United States Navy and belonged to the Thresher class named after it . The boat, which was put into service in 1961, was lost in diving tests on April 10, 1963, about 350 kilometers off Cape Cod on the east coast of the United States , killing 129 people. This made the Thresher the first sunken nuclear submarine .
The reason for the sinking is assumed to be uncontrollable water ingress. As a result of a short circuit that occurred as a result, the reactor switched itself off automatically, causing the boat's drive to fail, whereupon the Thresher sank below its depth of destruction. After a long search, the US Navy was able to track down the wreck and take photos that showed that the pressure hull was still stable when it was sinking and was only crushed by the rising water pressure at a great depth.
The wreck is still lying on the seabed at a depth of around 2,500 meters . Nothing is known about escaping radioactivity .
technology
As a unit of the Thresher class, the Thresher was almost 85 meters long, 9.8 meters wide and displaced 3,770 tons when submerged . The boat, propelled by a pressurized water reactor , reached speeds of 30 knots and, thanks to its nuclear propulsion, had a global range. The armament consisted of four in the bow about the height of the tower mounted torpedo tubes from which besides torpedoes also uum-44 subroc could be fired. The crew number was 16 officers and 96 men in action.
The Thresher was the lead ship of a new generation of submarines, which was specially designed to hunt other submarines. In addition, due to its construction with the new steel alloy HY-80 , the boat was able to dive 1,300 feet (400 meters) deeper than any other boat in the US Navy at the time and also had the best available sonar systems , which the boat together with its quiet propulsion system for best "secret hunter" of his time.
The construction costs were about 55 million US dollars.
Name and insignia
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The naming of the Thresher followed the tradition of the Navy to name submarines after marine animals . The common thresher shark was the godfather of this boat , a shark with a very long tail fin, which is also known as the “thresher shark” or “thresher shark” in English. A submarine that was able to sink several Japanese ships on 13 patrols, the Thresher (SS-200) , already bore this name during World War II .
The insignia of the Thresher is based on the eponymous shark and the capabilities of the boat . This is square and surrounded by a rope. In the background you can see blue stripes on a white background, which symbolize the great diving depth of the thresher . The submarine itself can be seen at the bottom right, its bow pointing directly at the viewer. The nuclear power symbol can be seen in the fuselage, which illustrates the type of propulsion. The boat also sends out sonar waves, symbolizing its ability to track down other ships. A thresher shark can be seen to the left above the submarine, its characteristic tail fin trailing the thresher . At the very bottom is the Latin word Vis tacita , which means silent strength . This official motto is also based on the performance of the thresher .
The type and the "Hull-Number" follow the name . In the case of the Thresher , this is SSN for Ship Submersible Nuclear , the classification for hunting submarines, and the 593 . That means the Thresher was the 593rd submarine in US Navy history.
history
construction
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The order to build the Thresher went to the Portsmouth Naval Shipyard in early 1958 . The keel of the boat was laid on May 28, 1958 at their shipyard in Kittery ( Maine ). On July 9, 1960, after just under 25.5 months, the hull was completed and the ship was launched . The thresher was launched bug ahead. This method was first used in submarines, because of its length and bow shape, it was preferred to the traditional stern-ahead launching. Accordingly, the place christening of the boat instead of at the rear. Godmother was Mrs. Mary B. Warden, the widow of Rear Admiral Frederick B. Warden, a submarine commander of the Second World War.
After the ceremony, the final equipment of the boat at the pier followed. The first trip under own power took place at the end of April 1961. However, there were already problems with the first dives. Test drives on the 30th of the month in shallow waters went well, but the next day instruments installed for test purposes indicated problems well before the intended diving depth was reached. The commandant, Commander Dean L. Axene, abandoned the dive; In the shipyard , however, it was found that the instruments displayed incorrect values. After the rest of the tests were positive, the Thresher was officially accepted into the US Navy on August 3, 1961.
First trips
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At the beginning of her service, the Thresher carried out further test drives. The first voyage during which the Navy wanted to determine the volume of the thresher in action took them to the Andros Island area . The results of these tests were positive and the boat was even quieter than hoped. Then the first operational simulations began off the coast of New England . The Thresher played "cat and mouse" with the American submarines Skate and Tullibee . After some repairs and maintenance work, the Thresher took the diesel-electric submarine Cavalla to San Juan , Puerto Rico .
When the two boats were in port on November 2nd, the Thresher shut down its reactor and drew the energy for light, air supply and cooling from its own diesel generator . This was necessary because there was not enough energy available on land to supply the ships at anchor, as is actually standard. When the Thresher's diesel generator failed, the ship drew its energy from the emergency reserve, consisting of large batteries . The decision was made late to restart the reactor, a process that costs time and energy. Therefore, all non-vital energy consumers were turned off, including the air conditioning, which heated areas on the boat to up to 60 ° C. Ten hours after the generator failed, the batteries were discharged, but the reactor had not yet started. Therefore, the Cavalla had to supply the nuclear submarine with electricity via cables, which enabled it to successfully start up the reactor.
After a few weapons tests, maintenance work followed around Christmas 1961, and from February 1962 the first tests of the sonar system under the direction of the Navy Underwater Sound Laboratory off New London , Connecticut . In March the Thresher drove simulated hunting missions against the Cavalla and the Hardhead . In April, the boat experts took antisubmarine warfare on board and demonstrated his skills again against the Cavalla .
The Thresher spent the period from mid-April to mid-May in the Electric Boat shipyard in Groton , Connecticut, where they were equipped with measuring instruments for their upcoming tests. The thresher should be moved south to carry out so-called "shock tests". The hull is exposed to the shock effect of nearby underwater explosions in order to find possible structural weak points and, if necessary, to remedy them. On the way to the Key West , Florida area , where the tests were to take place, the Thresher docked at Cape Canaveral , where a tug damaged the ballast tank. The actually relatively insignificant damage had to be repaired before the shock tests; this took place in the next available dry dock, which in turn was that of "EB" in Groton. After the short repair, the tests finally took place. For two weeks, the thresher was thrown with depth charges, which exploded at preset distances from the submarine . In the meantime, it was also determined whether the ordeal had made the submarine louder. The tests were finished in early July, and shortly afterwards the Thresher was back in Portsmouth. In the middle of the month, the crew let family members on board who were allowed to take part in short dives.
The boat then underwent the so-called Post Shakedown Availability (PSA) , a period during which the errors and problems found during the test drives were to be eliminated. At the Thresher , the PPE had been postponed because the boat had to take part in exercises that were supposed to demonstrate the performance of the boat, in addition to pure test drives. During the nine months in dry dock at the Portsmouth Navy Yard in Kittery, engines and other parts of the boat were exchanged; there were a total of 875 work orders. In some cases, holes had to be cut in the fuselage, which were later welded shut. At the beginning of 1963, Commander Axene was transferred to the John C. Calhoun , the new skipper of the Thresher was Lieutenant Commander John Wesley Harvey. The docking time lasted until April 1963.
Downfall
On the morning of April 9, 1963, around eight o'clock, the Thresher cast off the pier in Portsmouth for the first time after her docking time. The boat should do initial diving tests in shallow water over the continental shelf to check if the boat is leaking at any of the welded points or if there are any other problems. In addition to the military crew, there were 17 civilians on board. These were employees of the building yard and of suppliers. The military also included seconded officers from coastal commandos who were supposed to monitor the diving tests. The total crew number was 129.
The Thresher left the port with the Skylark , a submarine rescue ship that could rescue people from submarine wrecks, provided they were not deeper than 850 feet (250 meters). In addition, the Skylark stayed in contact with the submerged submarine via a Gertrude , an "underwater telephone". Such a procedure was standard in diving tests of new or just overhauled submarines.
The first attempts at diving that morning, east of Boston , Massachusetts , went smoothly. The two ships then agreed on a point about 220 nautical miles east of Cape Cod where they would meet the next morning. There the seabed was deep enough that the thresher could reach its greatest diving depth. The ships met on April 10, 1963 at 6:35 a.m. The meeting point was 41 ° 46 ' N , 65 ° 3' W . At 0747, the Thresher began the descent, which should lead her to a depth of 400 meters. The boat should make stopovers more often and the crew should look for leaks or other problems. At 7:52 a.m. it happened at a depth of 400 feet (125 meters). At 8:09 a.m. the Thresher had sunk to 650 feet (200 meters) and at 8:35 a.m. she passed 1,000 feet (300 meters). At 8:53 a.m., the boat was near the maximum safe diving depth of 1,300 feet (400 meters). At 9:13 am, an unclear message was finally received on the Skylark , which is today considered to be the last clearly understandable words received by the Thresher : “We are experiencing minor difficulties, have positive up-angle, and are attempting to blow "(Eng. About " We have small problems, have a positive angle of attack, try to blow " ). This means that the commander of minor problems, the hydroplane used to the boat to lift the bow and thereby control the direction of surface. In addition, he let “blow on”, ie compressed air flow into the ballast tanks of the submarine, which are filled with seawater during the dive, in order to increase the static buoyancy . At 9:18 a.m., the Skylark received one last message that was completely incomprehensible. Some crew members believe they have heard the words "(exceeding) test depth", others speak of "nine hundred north". Shortly afterwards, the Skylark heard noises that crew members interpreted as coming from bulkheads collapsing under the water pressure.
Search for the wreck
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After communication with the Thresher was broken, the Skylark sent a radio message to the Navy and began searching for the submarine. Maritime patrols reached the scene of the incident at noon, followed by other submarines as well as destroyers and cruisers in the afternoon . Another underground rescue ship, the Recovery , also helped with the search. The two rescue ships soon found small oil spills and debris on the surface, which fueled the worst fears. At 8:00 p.m., the Navy issued a press release that a submarine was "overdue" and "allegedly missing". Admiral George W. Anderson gave a television interview at 9:30 p.m. The then Chief of Naval Operations stated that the seabed in the area in question was 8,400 feet (2,560 meters) deep and that this would make it impossible to rescue the crew if the submarine sank. The last hope is that the radios of the Thresher were defective and that the boat would not have been recognizable in the surf after it had possibly reached the surface of the water and therefore headed for the harbor alone. He also reported on the discovered oil and the debris, which, however, did not represent a clear indication of the sinking, as a clear assignment to the submarine was not possible.
During the night, other ships reached the area and looked for the Thresher , but still found no sign of life from the boat. At 10:30 the next morning, Admiral Anderson gave a press conference officially declaring the loss of the thresher . Meanwhile, the Atlantis II , a deep-sea research vessel belonging to the Woods Hole Oceanographic Institution , had reached the site of the accident. The test instruments of this ship confirmed initial measurements, in which no increased radioactivity was measured in the region and on the rubble. The Atlantis and several similar ships found in the following ten days with underwater cameras and sonar around a dozen irregularities on the seabed, the wreck of Thresher could have been, but more tests were the places without success.
In order to better understand the descent of the Thresher , the Navy sank an old car body on April 26 , but lost sonar contact during the sinking. Thereupon plans were started to sink a decommissioned submarine. The Toro was fitted with sonar reflectors and was due to be sunk on May 20th. Shortly before, however, a first field of debris was found on the seabed and the attempt was canceled. The research vessel Conrad pulled towing cables with small nets across the sea floor and was able to recover three packs of O-rings , which are used to seal hydraulic devices on ships. The warehouse number on one of the bags could clearly be assigned to the thresher . These were the first parts that could be safely assigned to the submarine. However, no photos of the wreck could be taken afterwards either. It was not until mid-June that Conrad was able to take pictures of a pipe and a metal plate. Thereupon the Navy used the deep submersible Trieste , which had been transported to Boston shortly after the accident.
The Trieste dived for the first time on June 24th, but found no trace of the wreck. Another dive took place on June 26th, during which sonar contact was made with a 60 foot (18 meter) long piece of metal, but after contact was lost, it could not be grasped again. The object remained undetectable the next day, but parts with the visible inscription "SSN-5" were found. On June 29, the submersible was able to make out two craters in the silt of the sea bed. On June 30, malfunctions occurred on board the Trieste , so that she had to be towed back to Boston. The diving trips could not be resumed until August 23rd. On August 24th and the following days, close-ups of the wreck of the Thresher were taken aboard the Trieste (position 41 ° 46 ′ N , 65 ° 3 ′ W ). On August 28, the Trieste recovered a pipe and other metal parts that belonged to the Thresher . After carefully examining the photos, the Navy finally announced on September 5 that parts of the thresher's fuselage had been found and that the large-scale search could therefore be ended.
During the entire search, Soviet cargo ships and fishing trawlers were in the area and at times came very close to the American ships. Precisely because the US Navy had asked all civilian ships to avoid a radius of 25 miles around the search area (this was to prevent another ship from ramming the Trieste when surfacing or rubbish thrown into the sea from damaging the submerged boat) Suspicion suggests that these ships were supposed to collect intelligence material about the search and the technologies used.
In 1964, the Navy sent the specially equipped ship Mizar to the scene of the accident in the Atlantic to take more photos of the wreck, which was also achieved with a special deep-sea probe.
In 1985 the US Navy funded deep-sea researcher Robert D. Ballard's search for the Titanic on condition that he also investigate the two submarines Scorpion and Thresher, which sank in the 1960s .
root cause
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What led to the downfall of the Thresher has never been clarified for certain. Explosions of any kind can be ruled out. The boat was on a test drive and was therefore completely unarmed; an uncontrolled nuclear explosion in the reactor was physically not possible. A torpedo attack by a third ship or boat can also be ruled out, as the Skylark should have heard the detonation of the weapon. A possible collision can also be ruled out with great certainty, as no other submarines were detected in the region.
The most likely cause is the break in a pipeline that transported seawater through the pressure hull to cool the reactor. These lines were soldered together with silver instead of welded together , which would have been safer with the pressure 400 meters below the surface. After problems with silver solder joints on other boats in the fleet, it was decided in 1961/1962 that pipes that are exposed to the external pressure of the water must be welded. On the Thresher , too , in ultrasonic tests during the overhaul, 14 percent of the soldered joints were declared to be inadequate in random samples, but no inspection of all soldered joints or a repair of the defective connections were made. One of these pipes seems to have burst, presumably in the engine room, whereupon the inrushing water triggered a short circuit through which the reactor was “ scraped ”, meaning it was automatically switched off in an emergency. The loss of propulsion and thus the propulsion, combined with the loss of buoyancy due to the ingress of water, would have caused the thresher to sink .
As announced in his last message, the commander would then start an emergency blowing maneuver. Such a blowing maneuver had never been carried out from this depth. Only years later, when the Thresher's sister boat , the Tinosa , carried out corresponding tests, did it become clear that problems could arise that prevent the compressed air from being forced into the ballast tank. Due to the Joule-Thomson effect , the compressed air cooled down considerably as it flowed through the pipe system and expanded in the process. As a result, water condensed in the pipes froze to ice. This blocked filter installed in valves, so that after a short time no more water could be displaced from the tanks. Due to the loss of buoyancy that could not be compensated for, the boat ultimately sank to a depth of around 1950 feet (600 meters) and was crushed by the water pressure. The wreck was torn into several parts during the descent. The fact that the pressure hull of the Thresher was still intact during the sinking and was only crushed during the descent is also made clear by the noises heard by sonar operators on the Skylark . During their service in the Second World War, they were familiar with the similar noises of the bulkheads breaking under water pressure.
Investigations
On April 13, the Navy began an investigation, during which 120 witnesses were heard in eight weeks. The statements filled a total of 1,700 pages of paper. A hearing was also held before the United States Congress before the Joint Committee on Atomic Energy , whose report was published in book form on 192 pages. The proceedings came to the conclusion that the above-mentioned cause was to be assessed as the most likely (even if the effects of the Joule-Thomson effect on submarines at great depths were still unknown at the time). The press release issued by the Navy's Committee of Inquiry on July 20, 1963 read literally:
- A flooding casualty in the engine room is believed to be the "most probable" cause of the sinking of the nuclear submarine USS THRESHER, lost April 10, 1963, 220 Miles east of Cape Cod with 129 persons aboard.
- The Navy believes it most likely that a piping system failure had occurred in one of the THRESHER's salt water systems, probably in the engine room. The enormous pressure of the sea water surrounding the submarine subjected her interior to a violent spray of water and progressive flooding. In all probability water affected electrical circuits and caused loss of power.
- [...]
- Among its opinions, the Court stated that "the evidence does not establish that the deaths of those embarked in THRESHER were caused by the intent, fault, negligence or inefficiency of any person or persons in the naval service or connected therewith."
- (dt:
- It is believed that engine room water ingress is the "most likely" cause of the sinking of the nuclear submarine USS THRESHER, lost on April 10, 1963, 220 miles east of Cape Cod with 129 people on board.
- The Navy believes it is most likely that a pipeline failure has occurred in one of the THRESHER's saltwater systems, presumably in the engine room. The enormous pressure of the sea water surrounding the submarine exposed its interior to a violent spray of sea water and progressive flooding. Most likely, the water attacked electrical circuits, resulting in a power outage.
- [...]
- Among other things, the committee gave the assessment that "the evidence does not corroborate that the death of the passengers on the THRESHER was caused by the intent, error, negligence or inefficiency of persons in the service of the Navy or persons associated with it." )
The Committee of Inquiry thus explicitly rules out human error, both in the shipyards and on board the Thresher . A fundamental design error of the Thresher class was also denied, but warnings were given to better control systems that are exposed to water pressure and to rethink their design and to train better ship safety even under extreme conditions such as water ingress.
consequences
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The accident had several consequences, some of which were significant, for the Navy.
After losing the Thresher , Admiral Hyman Rickover started a program called SUBSAFE , with which he put quality assurance in the construction of nuclear submarines more into the foreground. Particular attention was paid to the processing of all parts that are exposed to water pressure. In addition, the Navy began to develop deep-sea rescue boats, so-called Deep Submergence Rescue Vehicles (DSRV). These boats were intended to enable the Navy to rescue survivors from depths of up to 5,000 feet (1,500 meters). In 1970 the first of two boats of the so-called Mystic class was put into service.
However, the accident did not have any environmental consequences. After the sinking, there was no increased ionizing radiation in the region, showing that the reactor chamber was able to withstand the pressure of the water. The Navy also assured that the seawater could not damage the chamber in the long term. This is significant in that the Thresher wreck lies in the northern reaches of the Gulf Stream .
literature
- Joint Committee on Atomic Energy: Loss of the USS Thresher. University Press of the Pacific, ISBN 0-89875-492-5 (Transcription of Congressional Hearing Regarding Loss of Thresher ).
- John Bentley: The Thresher disaster: The most tragic dive in submarine history. Doubleday 1975, ISBN 0-385-03057-6 (English).
- Norman Polmar: The Death of the USS Thresher: The Story Behind History's Deadliest Submarine Disaster. Lyons Press Guilford, CT 2004, ISBN 1-59228-392-6 (English).
- Cay Rademacher : The Thresher's Last Ride. In: Geo 04/1996. ISSN 0342-8311
See also
Web links
- Pictures of the Thresher on history.navy.mil (English)
- Thresher Base - United States Submarine Veterans (English)
- AmericanHeritage.com / What Sank the Thresher? (English)
- Thresher on eternal patrol (English)
Footnotes
- ↑ from: Terzibaschitsch: Sea power USA . Bernard & Graefe Verlag, Bonn, ISBN 3-86047-576-2 , p. 513.
- ↑ Commander Submarine Force, US Pacific Fleet, Submarines Lost or Damaged before and after World War II. ( Memento of the original from January 29, 2006 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. (English)
- ↑ A Moment in Time Archives: The Sinking of USS Thresher - II ( Memento from September 4, 2006 in the Internet Archive ), ehistory.osu.edu (English)
- ↑ The salty Sailor ( Memento of November 30, 2006 in the Internet Archive ) (English)
- ↑ quoted from a reprint of the press release of the Navy Investigative Committee in Polmar 2004, pp. 185f
