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This is the story behind two artist’s sketches taken from an official report titled Deep Ocean Search in the Thresher Loss Area, 1964 (ONR-24). The report, dated February 9, 1966 is to Rear Admiral John K. Leydon USN, Chief of the Office of Naval Research, and Commander of Task Force 168. It is from the author of this paper who was also Commander Task Group 168.1. Two searches were conducted in the THRESHER loss area. (See figure 1) The first was in 1963 starting on April 1 O’h of that year which was the day the Thresher (SSN593) casualty occurred. The second was in the summer of 1964 and is the subject of the report to Rear Admiral Leydon.

THRESHER was attached to the Submarine Development Group II in New London, Connecticut. I was the Commander of the Group and eventually became the long tenn search commander for both the 1963 and 1964 search operations.

The first graphic (Figure 1) is the location of USS THRESHER (SSN 593) now in broken parts on the continental shelf about 220 mile east of Cape Cod in waters 8250 feet deep. The geographic position is accurate enough in latitude and longitude, but the artist exaggerates the slope of the shelf terrain. It is more like a few degrees downward moving east.

THRESHER had been in the Portsmouth, New Hampshire Naval Ship Yard for a nine month post shakedown availability which started in late summer of 1962. On April 9, 1963, the ship had completed the yard time and left the Shipyard for its first under way operations. It arrived in the assigned operation area in the evening. Test dives and other shipboard routines were commenced the following morning, April 10, 1963. Commander Wes Harvey was now the skipper having relieved Commander Dean Axene, the commissioning skipper, in early fall of 1962. USS SKYLARK (ASR 20), a submarine salvage ship, was in company with THRESHER and was in fact in under-water-telephone communication (UQC) whenever THRESHER was dived.

A dive to test depth was carried out by THRESHER in mid morning and led to the catastrophic implosion of THRESHER’s pressure hull, probably at 2500 feet or deeper. The deep dive was underway no more than fifteen minutes when Commander Harvey reported having some difficulties to nearby SKYLARK. Not too many minutes then went by before SKYLARK heard first what sounded I ike ballast tanks being blown and later thereafter hull break up noises.

Vice Admiral Joe Grenfell, ComSubLant in Norfolk, ordered his deputy in New London, Rear Admiral Red Ramage to the dive scene as Commander of Task Group 89.1. On that day, there was no real search organization, no search technique, nor specific operating procedures for locating an object on the ocean floor at 8000 feet. In the first few frantic hours after Thresher’s Joss, a fu11 scale search effort consisting of 13 ships was laid on with the aim of scouring the ocean surface for possible life or floating signs from the THRESHER. Within 20 search hours, all hope for survivors had passed. The project then began to change from that of a standard Navy Search and Rescue operation to that of an oceanographic expedition. I was ordered to relieve Admiral Ramage and became the search commander for the balance of the summer. The operational group still remained Task Group 89.1 with ComSubLant in Norfolk as CTF 89.

The initial search area in 1963 was defined as a 10 mile by l 0 mile square area with the center at THRESHER’s most probable location. This latter point was named point Delta. Point Delta was determined by the navigational position of USS SKYLARK which was in UQC communication with THRESHER at the time of the latter’s breakup. The search area was reduced to 1 mile by 1 mile near the end of the summer.

There were certain clues which brought about this happy situation. The Woods Hole Research Vessel ATLANTIS II and science team searching near point Delta, were able to obtain bottom photographs of bits of wire, and twisted metal in an otherwise quite clean ocean floor. Next the CONRAD (AGOR-3) from the Lamont Laboratories at Columbia University , using a scallop dredge in the now reduced size search area recovered a packet of 0-rings with name plate data on each of the 0-ring envelopes. Soon ATLANTIS, also dredging, brought up a section of battery plate. Finally, CONRAD some time later, using a towed ocean floor rig with attached camera obtained good pictures of a submarine oxygen bottle sticking almost upright in the ocean floor and a I 0-foot piece of sheet metal identified as sonar baffling used on the exterior of a submarine.

The above evidence encouraged the use of the Bathyscaphe Trieste I. Lieutenant Commander Don Keach was its Officer in Charge. The hope was to have a close up look at the debris area by the three crew members who manned the TRIESTE I. Over a I 0 dive cycle period TRIESTE I did manage on dive # 6 to get into the debris area, did see what Keach described as “an automobile junk yard , and was able to retrieve a small section of twisted piping by use of an external claw arm. The piping was subsequently identified by the Portsmouth Ship Yard as part of THRESHER’s galley freshwater system. Extensive pictures in the area would have been great but the TRIESTE I Camera had broken down.

The first search for THRESHER was closed out by CTF 89 in late August 1963. There seemed to be little more to be gained now as the heavy sea state season was coming on. The point Delta area had been searched with evidence that the remains of THRESHER were close by the point . The ocean scientists needed time to think over their search system designs. TRIESTE I was in need of repairs. And finally the Court of Inquiry at the Portsmouth Ship yard had completed its review and closed out. The pressure was off the Navy to do much more.

The conclusion of the Court was that in THRESHER’s engineering spaces, massive internal flooding from a sudden break in a salt water piping joint could not be contained. The nuclear reactor was scrammed, most if not all electrical power was shorted out and the blow system could not handle the surfacing problem at the depth at which the casualty occurred.

THRESHER’s commissioning skipper was Commander Dean Axene. He has been required to submit a report to the CNO at the end of one year of operations. This he did in spring 1962. When I took over the Development Group in summer 1962, Dean showed me a copy of the report. The opening paragraph stated that the greatest single design deficiency in THRESHER was the literally yards and yards of sea water piping within the engineering spaces. Seawater piping feeds one side of a number of independent heat exchangers distributed throughout the engineering spaces. At alt submerged depths, pressure in this piping is exactly equal to sea pressure outside the hull. The Board of Inquiry conclusion and the reported design deficiency were certainly a match.

In Spring 1964, scientists in the Oceanographic community began talking up a second search for THRESHER for several reasons. They and others realized the inadequacies of deep ocean search and recovery techniques. A Deep Search, Salvage and Rescue Group (DSSRG) study had been organized in parallel with the Court of Inquiry. This group headed by a submariner, Rear Admiral Ed Stephan USN(Ret.), had completed its report which proposed a number of unique and provocative ideas for doing what could not be done in the case of the THRESHER casualty. It seemed a shame to many involved that THRESHER search and examination was only partly finished. Indeed it was now clear that US Navy operational readiness was inadequate in operating search sensors and recovery devices in world wide deep ocean areas.

The Pentagon leader for supporting a second THRESHER search was Dr. Jim Wakelin, the Under Secretary of the Navy with principle interest in Research and Development. Admiral Smith, CINCLANT, and Vice Admiral Grenfell, COMSUBLANT, would have none of it. Wake I in then proposed that the Chiefof the Office of Naval Research , Rear Admiral John Leydon lead a research project in THRESHER loss area. Leydon would be Commander Task Force 168 and be completely independent of the Atlantic Fleet commands. This was most unusual, as you can imagine, in that Rear Admiral Leydon was an Engineering Duty Only (EDO) officer. The latter normally do not command Navy ships at sea. Smith and Grenfell apparently had little option and hence the project was laid on. Admiral Smith did agree to provide the services of USS HOIST (ARS 40) for tending TRIESTE II and providing an on-scene base for CTG 168.1 who would be the at-sea leader of the so-called research project , “Deep Ocean Search in the Thresher Loss Area.

The units in TG 168.1 included USS HOIST (ARS 40), TRIESTE II (an overhauled and redesigned TRIESTE I), and the USNS MIZAR (TAK 272) with a research team on board led by Mr. Chester Buck Buchanan of the Naval Research Laboratory (NRL). MIZAR’s search methods utilized a towed device with an installed magnetometer, sonar and camera all of which were capable of performing at 8000 feet.

MIZAR also had a hull mounted acoustic triangulation system capable of real time bottom location of the towed device. The towed device was basically a number of metallic pipes welded together into a box like structure. Sensing equipment was hooked on to the pipes as appropriate. The operators called the device the fish. The connection between MIZAR and the fish was 12,000 feet of sturdy cable for tow and a parallel smaller cable for reception of a magnetometer signal, and for electrically turning the camera on and off when a sizeable signal was sensed by the magnetometer.

Admiral Smith as CINCLANT did set forth his views later for not conducting a second search for THRESHER. There were four: I) Little more could be learned about the cause of the THRESHER loss in that the Court if Inquiry had completed a very good analysis; 2) It was time to let the sailonnen of the THRESHER sleep; 3)TRIESTE was insufficiently advanced in deep-sea capability to contribute more than she had already; 4) Continued operations with Trieste posed the ever present further loss of life with inadequate compensation in the way of new learning.

Admiral Smith was certainly correct on numbers 3 and 4 above and number 1 to some extent. As for lessons learned however , one often learns as much from tragedy or near tragedy as from marvelous success. One near explosion on TRIESTE II showed this. The details follow later in the paper. Point # 2 was based on the enormous coverage of THRESHER’s loss by very aggressive newspaper, radio and TV activities. During the first summer search, Admirals Smith and Grenfell were both constantly badgered by congressmen, dependents, and media people asking millions of questions of which some were not so polite. The White House and the Pentagon shared also in initiating this often angry Why this and Why that? cross examination. THRESHER after all was the first nuclear submarine we had ever lost at sea. This was further aggravated because THRESHER was the first of a brand new submarine class. In 1963, we were in the middle of the cold war with Russia and did not need this kind of at-sea performance nor publicity.

From the view of the Oceanographic community however, locating and mapping out the entire THRESHER hull and components was a matter of significant scientific interest and challenge. And so the new search got under way in early June 1964.

The high point of the search was the ocean floor picture photography by the unmanned fish towed by MIZAR. The individual pictures were assembled in Figure 2, a photo mosaic artist’s sketch of the entire THRESHER debris field. The low point of the search was the horrible gasoline explosion that literally came within inches of happening to TRIESTE II shortly after surfacing from a several hour dive into the THRESHER loss area. Near misses make one humbly thank the Almighty. But they also make one think and think long about how come this potential horror almost happened.

A step back for a minute. Task Group 168. I was formed on May 18, 1964. The mission of the group was really to study deep ocean search methods and ocean floor navigation. There was no attempt nor expertise in the group to consider further the cause of THRESHER disaster. TRIESTE II led by LCDR Brad Mooney would test the ability of a manned vehicle team to perform. The MIZAR team led by Chief Scientist Buchanan from the NRL would do likewise using an 1111ma1111ed search vehicle. USS HOIST was a good support ship used for towing TRIESTE II to the operational scene, and for providing both logistical support and radio communication services for the entire three element Task Group.

It was apparent from the outset that supporting and operating the mam1edTRIESTE II was an order of magnitude more difficult than operating an unmanned vehicle.

This situation has continued to hold in the more sophisticated systems now available for deep ocean search and recovery. It is also true for the outer space projects of NASA.

In deep ocean work an unmanned search vehicle can be small in volume, can be sent down at any time day or night, in most any sea state as long as the topside crew can manage, can stay down longer and allow the topside crew to take chances not permitted when operating a manned vehicle. Concern for human safety changes everything when operating a manned vehicle .

The near catastrophic dive of TRIESTE II was its number 15 for the summer. On surfacing from this dive, the insulation in topside control wiring was discovered to be burned. The wire was sparking to the metallic deck. As a result of the sparking, a hole had been burned into the top of the hull battery tank. This tank was in the stern of TRIESTE II and was surrounded with salt water. Had the hole been burned a mere 8 inches or so further forward on the topside of TRIESTE JI, 75,000 gallons of hi-octane gas would have been exploded. All five or six TRIESTE II crew members topside would have been killed and the flash from the explosion could have severely burned bridge and deck personnel on nearby USS HOIST. TRIESTE II without doubt would have headed back to the ocean floor. This was a low point of the summer operation. HOIST and TRIESTE II returned to Boston for repairs.

Brad Mooney as Officer-in Charge ofTRlESTE II took the whole matter of the near horror most seriously. TRJESTE I and 11 were really only pieces of laboratory equipment supported by laboratory research money. The Bureau of Ships had assumed no responsibility for design and safe operation of either of the TRIESTES. Further, there was no specific fleet command like a submarine division command, for example, to insure adequate operational procedures and training prior to deployment. Thanks to Brad, others in the Submarine Force were soon aware of these problems and eventually Submarine Development Group I was established on the west coast to be the home for future Navy Deep Search and Rescue vehicles. Brad was a major leader in bringing about this latter happening. His motivation, and that of many other alerted submariners, was the driver that eventually produced a first class deep ocean search and recovery capability in the U.S. Navy.

The high point of summer 1964 was the many photographs taken by MIZAR. Buchanan and his NRL team had spent the entire winter of 1963 in designing, and installing equipment on MIZAR. Clever search tactics that produced the Mosaic shown in Figure 2 were also developed. Search tactics commenced by moving slowly (at one knot) through the search field with the towed fish 12 to 15 feet off the ocean floor, with camera eye closed, but with the magnetometer system operational. When and if the magnetometer indicated a hit, the MIZAR was put into a tight turning circle and the camera turned on. As long as the magnetometer reading was high the camera eye was held open until finally there was no more camera film. The fish was then hauled in for are review of photographs taken.

The heroes of the second summer search efforts were certainly Buck Buchanan and his MIZAR team. This included photographer R.N. Sibley of the Naval Reconnaissance and Technical Support Center (NRTSC).

THRESHER debris field mosaic (Figure 2) was put together by TG 168.1 staff members at the headquarters ofNRTSC at Suitland MD. Photographs taken mostly, but not all, by MIZAR, were laid out on a large floor, perhaps 40 by 50 feet in one of the NRTSC buildings. All photographs had to be resized as if taken at 10 feet height off the ocean floor and preciously located in their correct geographical position relative to the other photographs.

Individual components of the mosaic were sketched onto the artist’s panel with identifying numbers (1 through 10) assigned to each individual major component.

In Figure 2, a geographical plot shows where the numbered parts are finally located relative to each other. A summary statement on page 8 of the final report to CTG 168 (ChiefofNaval Research) is “The THRESHER hulk is located at 41° 44.5′ N, 64° 56.4′ Win 8250 ft. of water, is split into six large parts, and occupies an area on the bottom no larger than 400 yd. by 400 yd.

I did talk to technical people at the Naval Ships Research and Development Command at Carderock, MD as the report to CTG 168 was being prepared. They had conducted model tests as a means of understanding the scenario when THRESHER passed through crush depth. From Figure 2, they pointed to the likelihood of THRESHER collapsing first at its tail section. The idea of major flooding in the engineering spaces plus the squeezed shape of part #l (tail section) seemed to support this conclusion. They suggested that this implo-sion of part# l developed a huge wall of water which moved forward at tremendous speed to blow off the various sections forward of the tail section. This all took place in milli-seconds of time. The smooth hydrodynamic shape of intact THRESHER thus became instantly a set ofloosely related jagged parts looking and falling randomly like large leaves off a tall tree. Part #8 is connected to THRESHER’s reactor compartment. The reactor itself was never identified and is believed to be buried under the section one sees as part #8.

With out question, all human life on THRESHER was ended instantly when the THRESHER stem imploded at the submarine’s crush depth.

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