The US Navy’s Mystic docked to a Los Angeles class attack submarine.
Rescue operations and escapes from sunken submarines have made up an important part of this history of underwater disaster, and rightly so. For it is man’s steadfast fortitude in the face of impossible odds that gives purpose to what would otherwise be no more than a macabre catalogue of material and human destruction.
Until 1939 the United States had, in general, adopted escape routines similar to those employed by the Royal Navy with the emphasis on individual survival. But the success of the Squalus rescue turned thoughts towards multiple escapes with the aid of externally controlled diving bells. And this aspect of underwater survival was given additional impetus in the post-war period with the advent of nuclear-powered vessels and the greater depths at which they are designed to operate. Development, however, was slow. And it was only after a major disaster that the necessary funds were made available.
Within days of the Thresher tragedy a Deep Submergence Systems Review Group was set up to assess the situation and it was given a generous five-year period in which to come up with the answer. Its brief was to ‘develop a deep-submergence rescue vehicle (DSRV) which could operate below the collapse depth of our fleet submarines and which could search for and rescue surviving personnel.’
The value of the bathyscaphe Trieste had already been recognized a number of years before the Thresher went down and the US Navy had purchased the vessel from Professor Auguste Piccard in 1957. Its potential was vividly illustrated in 1960 when it reached a depth of 35,800 feet in the Challenger Deep in the Marianas and it was clear that the new DSRV must be based on a combination of the bathyscaphe and the McCann rescue-bell. By 1966 the Review Group’s plans had matured sufficiently for orders to be placed with Lockheed for the first two Deep Submergence Rescue Vessels. DSRV-1 was laid down on 24 January, 1970.
On delivery in August, 1971, it was found that DSRV-1 had cost a staggering $41,000,000 to develop and it was small consolation that DSRV-2, completed the following year, had halved this prodigious expenditure to a mere $23,000,000. Both vessels carry a crew of three and are capable of lifting twenty-four survivors on each ascent. Like the McCann bell the DSRV seats itself onto a special escape hatch on the submarine’s hull and, thanks to improvements in technology, a watertight coupling can be obtained with the sunken boat listing up to 45° from the horizontal.
The two prototype DSRVs weigh 35 tons, have an overall length of 49.2 feet, and diameter of 8 feet. Their conventional cigar-shaped appearance is misleading, for the onlooker sees only the outer shell. Inside this fibreglass casing are three interconnected spheres made from HY-140 steel which contain the operating crew, the rescue chamber and airlock, and the passenger space. Using a combinatior of propellers and thrusters the vessels can made a 5-knot maximum on their special electric motors and have a diving endurance of 12 hours at 3 knots. Their depth limit is stated to be 5,000 feet.
Unlike the McCann rescue diving-bell, which has itself been updated and can now accommodate eight survivors from a maximum depth of 800 feet, the DSRV is launched from a submerged mother submarine and survivors are transshipped to the parent vessel under water instead of being returned directly to the surface. Both launching and recovery take place at approximately 500 feet but the technical thinking behind this rather unusual system of operation is not known.
It was planned to put six DSRVs into service and they were to be supported by three mother-ships – the submarines Halibut, Finback, and Hawkbill. Two DSRVs were to be based at each of San Diego, Charleston and New London and, in the event of a Subsunk emergency, one vessel would be flown to the mothership nearest to the disaster in a giant Lockheed C-5 jet cargo aircraft backed by a specialized road transport unit.
But despite the grandiose programme set out by the Deep Submergence Systems Review Group only two of the original DSRVs, now named Mystic and Avalon, were built and nothing more has been heard of the other projected units. One reason for this failure to construct any further DSRVs was officially attributed to a cost over-run of 1,500%. Sceptics, however, questioned the value of the DSRV on other grounds, pointing out that as they were intended to operate below the crushing depth of the crippled submarine there were unlikely to be any survivors still alive to be rescued. However, within the limits of safe submergence, that is to say where the hull of the submarine remains intact, there is little doubt that the DSRV will prove to be a useful rescue vehicle, especially at depths below 800 feet, the maximum safe diving limit of the latest McCann-type rescue bell.
As it happens there have been no disasters in recent years to test the practical viability of the DSRV under operational conditions, but in September, 1986, Mystic took part in an exercise off Stavanger during which she evacuated a substantial number of ‘survivors’ from an American submarine as it lay ‘disabled’ on the floor of the Norwegian Sea. The exercise, which included a piggyback ride to the rescue zone by the Mystic clamped to the outer casing of the submarine Billfish, proved a complete success. As similar exercises now take place on a regular basis and include both American and NATO naval forces the prognosis for survival in the event of a major underwater accident is decidedly better than it was even a decade ago.
Until the recent establishment of the UK Submarine Rescue Service the Royal Navy continued to put its trust in the free-escape system and the collapsible twill trunk which, it will be recalled, Ruck-Keene had wanted to scrap nearly fifty years ago. As this history of underwater disasters has demonstrated it is a system that has had both successes and failures. But instruction in free escape procedures still remains an important and integral part of the submarine training programme at Fort Blockhouse where every prospective submariner is required to make a free ascent in the escape tank that forms such a prominent feature of the Gosport landscape. Training is for real and, although all possible safety precautions are taken, the occasional tragic accident still occurs. And even as these words are being written British newspapers are carrying reports of a fatality during a routine underwater escape simulation in the Fort Blockhouse training tank.*
Immersion suits have been updated in design and remain standard issue, and it is interesting to note that Britain’s first nuclear submarine, Dreadnought, was designed to incorporate one-man escape chambers similar in concept to those suggested by the Ruck-Keene Committee back in 1946. Clearly, even at that time, individual escape was still the Admiralty’s preferred policy in the event of an underwater accident.
Until recently the only significant change in the Royal Navy’s approach to submarine survival was the switch to BIBS – Built-in Breathing System – similar in principle to Momsen’s pre-war central oxygen manifold pioneered by the US Navy. This obviates the necessity for individual breathing apparatus and is intended for use during the dangerous flooding-up period. A mixture composed of 60% oxygen and 40% nitrogen is fed into the central manifold from pressurised cylinders and survivors can draw their requirements through flexible rubber mouthpieces. A demand valve ensures that the mixture is not wasted and there is also provision to tap into the manifold for the inflation of life-jackets.
But despite the elaborate equipment and the rigorous training that goes with it, the free-escape method is of doubtful utility at depths approaching 300 feet. And it needs hardly be added that most nuclear submarines habitually operate a depths far below 300 feet.
The Royal Navy, however, is now following in the footsteps of its American cousin and since 1983 has retained on permenant contract a manned submersible, LR5, owned by a commercial company, Cable & Wireless Marine, with technological backing from another private concern, Rumic Ltd. LR5 is 9.8 metres in length and has a beam of 3 metres. Its pressure hull is constructed from glass-reinforced plastic and it is powered by a 10 HP 120-volt DC motor with an endurance range of six to ten hours and a maximum speed of two knots. The vessel’s four-man crew are all civilian specialists.
LR5 is intended to form an integral part of the NATO submarine rescue organization and may find itself working alongside the Italian mini-submersible MSM1 or one of the American DSRVs. In addition to this manned submersible the Royal Navy also owns and operates Scorpio 45, a remotely controlled unmanned underwater vehicle whose primary function is to carry out television and video surveys of a sunken submarine and to transfer life-support stores and equipment to survivors via the boat’s escape hatch. Such stores would include oxygen candles and carbon-dioxide absorbant to keep the air inside the submarine breathable for the duration of the rescue operation.
The Royal Navy’s Submarine Escape and Rescue Project only came into being in 1992 and at this early stage it is not possible to provide a detailed account of its work. Its stated purpose is to support the Flag Officer Submarines and the Submarine Escape Training Tank at Fort Blockhouse (HMS Dolphin); to provide rescue facilities and develop escape and rescue equipment; and to act as the focal point for all operational and material aspects of submarine rescue. Suffice it to say that the establishment of such a service by the Ministry of Defence Support Command demonstrates that the authorities now recognize the need for instant response and the application of advanced technology in the pursuit of submarine safety. And so far as the Royal Navy and NATO are concerned it augers well for the future.
Before closing this review of the latest developments it must be added that several other navies are now organizing search and rescue systems on the lines of those being pioneered by Britain and the United States. Italy, as befits the nation that first created the mini-submarine and the human torpedo, has its own submersible MSM1; Russia and Japan are both building their own DSRVs; while Korea is procuring an LR5K from Britain. Australia, Libya, Finland, Pakistan and Taiwan are all in the process of acquiring some form of underwater rescue vehicle in the near future.
Despite the end of the Cold War there are still some 30,000 men living and working beneath the surface of the sea every hour of the day and night as the submarines of the world’s navies ply their lawful occasions. At this precise moment submarines are cruising beneath the icecaps of the North Pole seeking each other out in a monstrous game of hide-and-seek. Others are stalking the depths of the Atlantic and Pacific Oceans ready to release their megaton missiles on receipt of a coded signal from Washington, Moscow, London, Paris and, in all probability, Beijing. Still more are nosing the warm waters of the Mediterranean and the Caribbean, patrolling the coastlines of Latin America, guarding the shipping routes of southern Africa, moving stealthily through the China Sea and carefully quartering the vast wastes of the Indian Ocean.
All, regardless of nationality, run the same risks of death and disaster. For the submariner of 1995 shares the self-same dangers as the submariner of 1905. And like his predecessors in history he carries out his duties with the same dedicated vigilance remembering always that ‘a trifling mistake can be a possible cause of serious danger’.
In the words of the old naval prayer: Deliver us, O Lord, from the perils of the sea and the violence of the enemy. As we recall the disasters of the past let us all say a fervent amen to that.