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After three decades of fruitless searches, sonar and an undersea rover helped Israel discover the fate of the INS Dakar. By Henry Baumgartner

N THE DARX EARLY hours ofJanuary 25, 1968, the INS was sold and renamed, the totem pole was retired to a mu­ Dakar, an Israeli submarine newly purchased from se um, so it was not on board for the fatal voyage. The I the BrItish Royal Navy, was slicing at top speed totem remains on view in the Royal Navy Submarine through the eastern Mediterranean. The vessel had Museum in Gosport, England, to this day. passed Crete not long before on the way to its new The sub offered a choice of two drives, a diesel-elec­ home port of Haifa. Shortly after midnight, the Dakar tric mode where the propellers were driven by electric sent out a routine radio transmission. Then it vanished motors with the diesels producing the electric power, without a trace. and a faster (a bout 8 knots) direct-drive mode where Extensive searches were undertaken but proved fruit­ the diesels were connected directly to the propellers less. Over the years, further searches were conducted through a pair of clutches. in various areas of the Direct drive was not rec­ eastern Mediterranean, ommended for long peri­ but all to no avail. In Is­ ods, and it imposed an extra rael, the fate of the lost strain on the crew, requir­ sub and its crew of 69 has ing two officers to be on remained a topic of in­ watch at all times. What's tense interest, and early This model shows the Israeli submarine INS Dakar before its fatal voyage. more, under direct drive a this year, the government The sub had previously served in the British Royal Navy as the HMS Totem. loss of hydraulic pressure awarded a contract to could cause the stern Nauticos Corp. of Hanover, Md., which mounted yet plane-a sort of horizontal rudder that controls the dive one more search. angle-to jam in full dive position. The crew would have to manually disengage the clutch, which was normally op­ THE VOYAGE OF THE DAKAR erated hydraulically, in order to reverse engines so that the The Dakar was built by the British during World War II sub would not continue its dive straight to the bottom. and was known as the HMS Totem during its years in The modifications to the Dakar had reduced its maxi­ Royal Navy service. In the early 1950s, the boat under­ mum operating depth to 300 feet from 350. As Cmdr. went a program of refurbishment that was standard for Jonathan Powis, the staff officer for submarines at the boats of its class. The vessel was cut in half and a new British Embassy in Washington, pointed out, after the section with an additional battery was added, along with al terations the sub would have been almost 300 feet a 10-man diving chamber and a modified sail. The long, so "it wouldn't take long to achieve the diving streamlining was also improved. depth." Powis, however, said that loss of hydraulic All T-class submarines had names beginning with the power would not normally lead to catastrophe, because letter T, but the name of this particular submarine referred of the redundancy built into the systems. It was clear, to an actual totem. A Canadian Indian tribe had presented however, from the sub's rate of advance on its trip the vessel with a small totem pole, which always went to home that it was, in fact, operating almost continuous­ sea with the boat as a good lu ck talisman. When the ship ly in direct drive.

56 A U GUST 1999 ME C H AN ICAL ENG INEERI NG Full-scale tests, including a dive to 300 feet, were con­ In 1997, yet another effort to find the remains of the ducted prior to delivery. The Israelis chose the name Dakar was undertaken, with the formation of a joint Dakar, which is Hebrew for spineback, a type of fish. U.s.-Israeli committee to investigate the incident. In ad­ The Dakar's orders were to make a direct course dition to U.S. Navy personnel, the group included via Gibraltar to Haifa and to arrive February 2. The David Jourdan, president of Nauticos, and Thomas Det­ vessel, under the command of Lt. Cmdr. Ya'acov tweiler, who had been a member of the team that found Ra'anan, was advancing at a speed of 8 knots, and the the Titanic and who was now also with Nauticos. The Is­ captain asked to have his arrival moved up to January raeli team was led by Adm. Gideon Raz, who had com­ 28. Actually, the boat kept up a speed that would bring manded the Dakar's sister ship, the INS Leviathan, and it to Haifa on the 26th, a feat that would have set a had taken her over the very same route as the Dakar record for crossing the Mediterranean submerged. some months before the latter's disappearance. Major celebrations were planned for the Dakar's ar­ The U.S. Navy offered a deep-diving research sub, and rival, since at the time Israel's submarine fleet was tiny. Nauticos was invited to reinvestigate and advise on likely Downloaded from http://asmedigitalcollection.asme.org/memagazineselect/article-pdf/121/08/56/6354003/me-1999-aug3.pdf by guest on 28 September 2021 Israel, in fact, had been experiencing great difficulties areas to search. According to Jeff Burns, the marketing in acquiring such craft. manager at Nauticos, the committee examined every It was a time when international tensions were high, conceivable scenario of the submarine's disappearance even by Middle East for clues to w here they standards: The Six-Day might search. Aside from War between Israel and hostile action, plausible its Arab neighbors had theories included loss of taken place only a few hydraulic power leading months previously, re­ to jamming of the stern sulting in considerable plane and collision with a loss of territory by Egypt surface ship. and other Arab countries The theory that the and leaving a mood of craft had gone down in extreme tension in the shallow water was still area, particularly be­ popular, and the previous tween Israel and Egypt. shallow-water searches The Dakar was, in fact, were extended outward under orders not to ap­ to the limit of the Amer­ proach within 50 nauti­ ican sub's capabilities. cal miles of the Egyptian These areas were duly coast. Many Soviet searched and produced The bridge gyro repeater from the Dakar, showing the heading for its final intelligence trawlers, course, was found by the Remora lying face up at the botom of the sea. no sign of the Dakar, al­ along with aircraft and though the searchers did submarine patrols, were operating in the area, as were find the wrecks of two early Phoenician merchant ships. Egyptian subs. At this point, attention turned to the deep-water areas On its journey, the submarine communicated with its along the Dakar's intended route, despite the confusing base by Morse code every six hours, and reported its po­ evidence of the buoy. The deep-water search began the sition every day at 6 a.m. On January 24, the Dakar re­ next year, 1998. The American sub could not be used at ported its position just past Crete. The next three radio this depth, but the U.S. Navy contributed its DSILOS checks were conducted on schedule and gave no indica­ search system. The sub, however, was not found. tion that there might be anything wrong. The last veri­ fied transmission was one minute after midnight on the DISCOVERY AT LAST 25th. After that, silence. In February 1999, the Israelis invited bids on a contract, Searches were conducted inU11ediately by sea and air, which was won by Nauticos, and the operation go"t start­ but nothing was found. U.S. intelligence agencies failed ed again shortly thereafter. The idea was to continue to to pick up any "acoustic events," and there was no evi­ search the "box," the area of ocean where the conll11ittee dence of hostile action, despite the level of tension. had concluded the sub was most likely to be found. This There were various claims that Egypt had sunk the craft, would require a search of the area with deep-towed but no evidence to back up such a claim ever surfaced, sonar, with likely spots more closely investigated by a and searches in the area failed to turn up anything. camera-carrying robot craft. Nauticos had used a similar A rescue buoy from the sub washed up on the shore of method in 1995 in finding the I-52, a World War II the Gaza Strip 13 months later, leading naval experts to Japanese submarine that went down in the Atlantic. believe that the vessel had sunk in shallow coastal waters. Nauticos's Dettweiler led the project, and Williamson Accordingly, there were searches conducted off Egypt in & Associates of Seattle supplied its AMS-60 sonar the 1980s and in the Aegean in the '90s, again without search system, which Nauticos and Williamson per­ result. The mystery remained as deep and dark as ever. sonnel operated 24 hours a day while at sea. The AMS-

M EC II AN IC AL ENG INEERING AUGUST 19 9 9 57 60, according to Mike Williamson, the president of Williamson & Associates, is a wide-swath seabed imag­ ing system that can image the sea floor in strips 2,500 meters wide, providing high-resolution imagery. The device was used to methodically search a box approxi­ mately 60 by 8 nautical miles, as if "mowing the grass," as Williamson put it. The small camera-carrying remotely operated vehicle, or ROV, dubbed the Remora 6000, was built by Phoenix M arine Inc. of Arlington, Va. The Remora, a relatively small and light ROV that was put together in

only a few months, represented a return to the grass Downloaded from http://asmedigitalcollection.asme.org/memagazineselect/article-pdf/121/08/56/6354003/me-1999-aug3.pdf by guest on 28 September 2021 roots, according to Steve St. Amour of Phoenix Marine, who built the Remora himself. St. Amour observed that, despite the prevailing desire for ever larger and more powerful machines "like a teenager always want­ ing more horsepower," because of practical limitations on the size of the cables used in deep-sea operations, there is a practical limitation of 25 hp for deep-water electrohydraulic ROVs. Remora's small size (about 1,700 lbs.) gave it an advan­ tage in speed and maneuverability, wruch was enhanced by an unusual vector thrust configuration, with thrusters on each corner set at a 45-degree angle to the craft. N avigation support came from the U.S. Navy's Deep Submergence Unit. T he Oceanographer of the Navy, the N aval Meteorology and Oceanography Command, and the N aval Oceanographic Office also provided help under a cooperative research agreement. The AMS-60 sonar imaging system is launched into the seas between Two ships were chartered on Cyprus from EDT Cyprus and Crete to search the seabed for the remains of the Dakar. Towage and Salvage to hold the equipment. Large I­ beams served as foundations for the winches and had to back pictures of the broken-off sail and two major hull be welded to the decks, along with overboarding gear, sections lying nearby. and generators, lab space, and a towing system for the According to John Coombs, an operations engineer for AMS-60. The Remora itself also had to be installed. Nauticos who was with the search team, "The wreck The sonar sweep turned up some 200 contacts to be in­ looked like the hull had fractured around the boundary be­ vestigated; several of these met enough of the search cri­ tween the operations complex and the engine room. The teria that they were investigated with the Remora. One fore section was fairly intact, with the aft section resting of these, lying at 10,000 feet close to the center of the next to it at an angle, almost on top of it. The sail had fall­ search box, proved to be the forward section of a subma­ en to the side, and was somewhat corroded." The broken rine sail. Over the next several hours, the Remora sent hull exposed to view objects such as capstans, periscopes, sonar domes, and anchors. The bridge gyro repeater was lying face up, showing the last course set by the Dakar. Word was quickly sent to Israel and Admiral Raz ar­ rived to make a positive identification on Friday, May 28, whereupon the Nauticos team was asked to leave the site to avoid attracting attention while the relatives of the Dakar's crew were notified privately. N ews conferences and meetings with the relatives followed. Dettweiler prepared mosaic images and a final report for the Israelis, which was delivered in early July. The cause of the Dakar's sinking has yet to be determined. A forensic study may take place next spring. It's now also up to the Israelis to decide what to do about the remains. "To bring up the hull would be an order of magnitude more difficult" than the recent re­ covery of a hull sample from the Titanic, according to

Remora's camera recorded this image of the Dakar's escape trunk ladder, Jourdan of Nauticos. "But it is an Israeli tradition never which was a modification meant to allow commandos to leave the sub. to leave a soldier on the battlefield." _

58 AU G U ST 1999 M ECHANI CA L ENG IN EERING