0
Select Articles

The Sub that Vanished PUBLIC ACCESS

After Three Decades of Fruitless Searches, Sonar and an Undersea Rover Helped Irael Discover the Fate of the INS Dakar.

Mechanical Engineering 121(08), 56-58 (Aug 01, 1999) (3 pages) doi:10.1115/1.1999-AUG-3

This article discusses how sonar and an undersea rover helped Israel discover the vanished INS Dakar, an Israeli submarine that was purchased from the British Royal Navy. In February 1999, the Israelis invited bids on a contract, which was won by Nauticos, and the operation got started again shortly thereafter. The idea was to continue to search the “box,” the area of ocean where the committee had concluded the sub was most likely to be found. This would require a search of the area with deep-towed sonar, with likely spots more closely investigated by a camera-carrying robot craft. Navigation support came from the US Navy’s Deep Submergence Unit. The Oceanographer of the Navy, the Naval Meteorology and Oceanography Command, and the Naval Oceanographic Office also provided help under a cooperative research agreement. The sonar sweep turned up some 200 contacts to be investigated; several of these met enough of the search criteria that they were investigated with the Remora. Word was sent to Israel and a positive identification was done on Friday, May 28, 1999, and the relatives of the Dakar’s crew were notified privately.

IN THE DARX EARLY hours of January 25, 1968, the INS Dakar, an Israeli submarine newly purchased from the BrItish Royal Navy, was slicing at top speed through the eas tern Mediterranean. The vessel had passed Crete not long before on the way to its new home port of Haifa. Shortly after midnight, the Dakar sent out a routine radio transmission. Then it vanished without a trace.

Extensive searches were undertaken but proved fruitless. Over the years, further searches were conducted in various areas of the eastern Mediterranean, but all to no avail. In Israel, the fate of the lost sub and its crew of 69 has remained a topic of intense interest, and early this year, the government awarded a contract to Nauticos Corp. of Hanover, Md., which mounted yet one more search.

This model shows the Israeli submarine INS Dakar before its fatal voyage. The sub had previously served in the British Royal Navy as the HMS Totem.

Grahic Jump LocationThis model shows the Israeli submarine INS Dakar before its fatal voyage. The sub had previously served in the British Royal Navy as the HMS Totem.

The Dakar was built by the British during World War II and was known as the HMS Totem during its years in Royal Navy service. In the early 1950s, the boat underwent a program of refurbishment that was standard for boats of its class. The vessel was cut in half and a new section with an additional battery was added, along with a 10-man diving chamber and a modified sail. The streamlining was also improved.

All T-class submarines had names beginning with the letter T, but the name of this particular submarine referred to an actual totem. A Canadian Indian tribe had presented the vessel with a small totem pole, which always went to sea with the boat as a good luck talisman. When the ship was sold and renamed, the totem pole was retired to a museum, so it was not on board for the fatal voyage. The totem remains on view in the Royal Navy Submarine Museum in Gosport, England, to this day.

The sub offered a choice of two drives, a diesel-electric mode where the propellers were driven by electric motors with the diesels producing the electric power, and a faster (about 8 knots) direct-drive mode where the diesels were connected directly to the propellers through a pair of clutches.

Direct drive was not recommended for long periods, and it imposed an extra strain on the crew, requiring two officers to be on watch at all times. What's more, under direct drive a loss of hydraulic pressure could cause the stern plane-a sort of hori zontal rudder that controls the dive angle-to jam in full dive position. The crew would have to manually disengage the clutch, which was normally operated hydraulically, in order to reverse engines so that the sub would not continue its dive straight to the bottom.

The modifications to the Dakar had reduced its maximum operating depth to 300 feet from 350. As Cmdr. Jonathan Powis, the staff officer for submarines at the British Embassy in Washington, pointed out, after the al terations the sub would have been almost 300 feet long, so "it wouldn 't take long to achieve the diving depth." Powis, however, said that loss of hydraulic power would not normally lead to catastrophe, because of the redundancy built into the systems. It was clear, however, from the sub's rate of advance on its trip home that it was, in fact, operating almost continuously in direct drive.

Full-scale tests, including a dive to 300 feet, were conducted prior to delivery. The Israelis chose the name Dakar, which is Hebrew for spineback, a type of fish.

The Dakar's orders were to make a direct course via Gibraltar to Haifa and to arrive February 2. The vessel, under the command of Lt. Cmdr. Ya'acov Ra'anan, was advancing at a speed of 8 knots, and the captain asked to have his arrival moved up to January 28. Actually, the boat kept up a speed that would bring it to Haifa on the 26th, a feat that would have set a record for crossing the Mediterranean submerged. Major celebrations were planned for the Dakar's arrival, since at the time Israel's submarine fleet was tiny.

Israel, in fact, had been experiencing great difficulties in acquiring such craft.

It was a time when international tensions were high, even by Middle East standards: The Six-Day War between Israel and its Arab neighbors had taken place only a few months previo usly, resulting in considerable loss of territory by Egypt and other Arab countries and leaving a mood of extreme tension in the area, particularly between Israel and Egypt.

The Dakar was, in fact, under orders not to approach within 50 nautical miles of the Egyptian coast. Many Soviet intelligence trawlers, along with aircraft and submarine patrols, were operating in th e area, as were Egyptian subs.

On its journey, the submarine communicated with its base by Morse code every six hours, and reported its position every day at 6 a.m. On January 24, the Dakar reported its position just past Crete. The next three radio checks were conducted on schedule and gave no indication that there might be anything wrong. The last verified transmission was one minute after midnight on the 25th. After that, silence.

Searches were conducted inU11ediately by sea and air, but nothing was found. U.S. intelligence agencies failed to pick up any "acoustic events," and there was no evidence of hostile action, despite the level of tension. There were various claims that Egypt had sunk the craft, but no evidence to back up such a claim ever surfaced, and searches in the area failed to turn up anything.

A rescue buoy from the sub washed up on the shore of the Gaza Strip 13 months later, leading naval experts to believe that the vessel had sunk in shallow coastal waters. Accordingly, there were searches conducted off Egypt in the 1980s and in the Aegean in the '90s, again without result. The mystery remained as deep and dark as ever.

In 1997, yet another effort to find the remains of the Dakar was undertaken, with the formation of a joint U.s.-Israeli committee to investigate the incident. In addition to U.S. Navy personnel, the group included David Jourdan, president of Nauticos, and Thomas Dettweiler, who had been a member of the team that found the Titanic and who was now also with Nauticos. The Israeli team was led by Adm. Gideon Raz, who had commanded the Dakar's sister ship, the INS Leviathan, and had taken her over the very same route as the Dakar some months before the latter's disappearance.

The U.S. Navy offered a deep-diving research sub, and Nauticos was invited to reinvestigate and advise on likely areas to search. According to Jeff Burns, the marketing manager at Nauticos, the committee examined every conceivable scenario of the submarine's disappearance for clues to where they might search. Aside from hostile action, plausible theories included loss of hydraulic power leading to jamming of the stern plane and collision with a surface ship.

The theory that the craft had gone down in shallow water was still popular, and the previous shallow-water searches were extended outward to the limit of the American sub's capabilities.

These areas were duly searched and produced no sign of the Dakar, although the searchers did find the wrecks of two early Phoenician merchant ships.

At this point, attention turned to the deep-water areas along the Dakar's intended route, despite the confusing evidence of the buoy. The deep-water search began the next year, 1998. The American sub could not be used at this depth, but the U.S. Navy contributed its DSILOS search system. The sub, however, was not found.

The bridge gyro repeater from the Dakar, showing the heading for its final course, was found by the Remora lying face up at the botom of the sea.

Grahic Jump LocationThe bridge gyro repeater from the Dakar, showing the heading for its final course, was found by the Remora lying face up at the botom of the sea.

In February 1999, the Israelis invited bids on a contract, which was won by Nauticos, and the operation go"t started again shortly thereafter. The idea was to continue to search the "box," the area of ocean where the conll11ittee had concluded the sub was most likely to be found. This would require a search of the area with deep-towed sonar, with likely spots more closely investigated by a camera-carrying robot craft. Nauticos had used a similar method in 1995 in finding the I-52, a World War II Japanese submarine that went down in the Atlantic.

Nauticos's Dettweiler led the project, and Williamson & Associates of Seattle supplied its AMS-60 sonar search system, which Nauticos and Williamson personnel operated 24 hours a day while at sea. The AMS 60, according to Mike Williamson, the president of Williamson & Associates, is a wide-swath seabed imaging 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 approximately 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 Marine 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 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 wanting 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 advantage 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.

Navigation support came from the U.S. Navy's Deep Submergence Unit. T he Oceanographer of the Navy, the Naval Meteorology and Oceanography Command, and the N aval Oceanographic Office also provided help under a cooperative research agreement.

Two ships were chartered on Cyprus from EDT Towage and Salvage to hold the equipment. Large Ibeams served as foundations for the winches and had to be welded to the decks, along with overboarding gear, and generators, lab space, and a towing system for the AMS-60. The Remora itself also had to be installed.

Remora's camera recorded this image of the Dakar's escape trunk ladder, which was a modification meant to allow commandos to leave the sub.

Grahic Jump LocationRemora's camera recorded this image of the Dakar's escape trunk ladder, which was a modification meant to allow commandos to leave the sub.

The sonar sweep turned up some 200 contacts to be investigated; several of these met enough of the search criteria that they were investigated with the Remora. One of these, lying at 10,000 feet close to the center of the search box, proved to be the forward section of a submarine sail. Over the next several hours, the Remora sent back pictures of the broken-off sail and two major hull sections lying nearby.

According to John Coombs, an operations engineer for Nauticos who was with the search team, "The wreck looked like the hull had fractured around the boundary between the operations complex and the engine room. The fore section was fairly intact, with the aft section resting next to it at an angle, almost on top of it. The sail had fallen to the side, and was somewhat corroded." The broken 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 arrived 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.

The AMS-60 sonar imaging system is launched into the seas between Cyprus and Crete to search the seabed for the remains of the Dakar.

Grahic Jump LocationThe AMS-60 sonar imaging system is launched into the seas between Cyprus and Crete to search the seabed for the remains of the Dakar.

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 recovery of a hull sample from the Titanic, according to Jourdan of Nauticos. "But it is an Israeli tradition never to leave a soldier on the battlefield."

Copyright © 1999 by ASME
View article in PDF format.

References

Figures

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In