by James Jinks
In theory, the new computerized integrated command and fire control system could handle twenty-five submarine or surface ship contacts simultaneously and produce accurate fire control solutions for each one. However, submariners soon found that the poor bearing information provided by the main sonar and a lack of computer memory meant that the solutions displayed were sometimes unreliable. There was an understandable tendency to assume that because solutions were displayed in plan form on a computer screen they were necessarily accurate, when they were in fact portraying the best information on a contact available at the time.147 COs who were capable of recognizing when the information was incorrect would say their operators were suffering from a fictional set of symptoms known as ‘Kalman Syndrome’. As with most computers, the principle of ‘rubbish in, rubbish out’ applied and operators would often see a contact hurtling across the screen at vast speeds, until it was deleted. It took a great deal of effort by the operators to control the picture, to the continual frustration of command, and many submarine officers hankered after the old paper plots, which they understood better.148 Some even resorted to maintaining clandestine versions.149
The 1970s also saw considerable advances in submarine communications, an area that was notoriously difficult and beset by constant problems such as mast heights, immersion and ingress of water. Alongside the existing very-low-frequency (VLF), medium-frequency (MF) and high-frequency (HF) communications, three additional means of communication, some technical, some procedural, were introduced into Royal Navy submarines. The first was a process known as ‘Postboxing’. It involved a submarine arriving at a prearranged area, raising its wireless mast and transmitting and receiving communications from a nearby RAF Nimrod aircraft, which would then relay information to the relevant authorities. While innovative, the system depended on both submarine and aircraft sticking to complex schedules and being in the right place at the right time. The second means of communication, known as ‘Burbling’, was more rudimentary and intended for use during sensitive, time-critical operations when a submarine was unable to come to periscope depth and communicate using traditional means. In order to transmit a message a submarine CO would order a series of revolution movements, which corresponded with prearranged messages such as ‘in trail’, ‘breaking trail’ etc. These revolution movements would be picked up by SOSUS arrays, analysed and the appropriate messages extracted.
The third means of communication, the Submarine Satellite Information Exchange System, or SSIXS, revolutionized submarine communications and allowed almost instantaneous and secure two-way communications between submarines and operating authorities. Provided the appropriate satellite was free, communications traffic could be transmitted at any time and all outstanding traffic held by the shore station transmitted to the submarine in a matter of seconds. Developed by the Americans in the mid-1970s, SSIXS was fitted to all USN submarines in 1977 and a number of sets were made available to the Royal Navy by COMSUBLANT. Following successful trials a complete inventory was acquired and fitted to all Royal Navy submarines. SSIXS greatly aided the trailing of Soviet submarines as it allowed Royal Navy submarines to send reports to operational headquarters without breaking high-frequency radio silence. It also significantly enhanced UK/US inter-operability as both nations used the same system.
While these advances significantly enhanced the capabilities of the Royal Navy’s submarines, their weapons systems were still, to use the words of the then Flag Officer Submarines, Michael Pollock, in a ‘parlous condition’.150 As we have seen, the Mark 24 torpedo, on which the Submarine Service depended, had failed its acceptance trials and its designers were forced to return the torpedo to the development stage. In 1970 the former head of the Dreadnought Project Team, Rowland Baker, was called back from retirement and appointed head of a new organization known as the Torpedo Project Executive, to manage a ‘get-well programme’. While this intensive programme succeeded in resolving many of the torpedo’s defects, by the middle of 1970 there were still two major problems with the Mark 24: it consistently failed to pass within the required 15 feet of a target when it entered the final phase of an attack, which had significant implications for the lethality of the torpedo; and it had a tendency to roll when it was discharged from the firing submarine, severing the control wire. The Marconi Space and Defence Systems Company (GEC-AEI) had to employ some 270 men in order to resolve these problems.151 After development and engineering problems the Mark 24 Mod 0 torpedo finally entered service in 1974.
In any case, the Mod 0 variant of the Mark 24 had other shortcomings. At first, it had no anti-surface ship capability. When the Admiralty provided one, as the Mark 24 was so old, the design and engineering modifications required to update what was then late-1950s-era technology meant that the result, the Mark 24 Mod 1, was essentially a new torpedo. But it too suffered from a number of shortcomings. It was limited to speeds of up to 24 knots and thus had no speed advantage over surface ships. At higher speeds the torpedo’s flat nose created so much cavitation that it either lost what contact it had with a target or was incapable of gaining contact at all.152 The torpedo’s designers were also unable to guarantee that its warhead, which was only 300 lb compared with the 800 lb warhead on the old Mark 8, would sink a surface ship. Indeed, Admiralty studies indicated that the probability of sinking a Soviet ‘Kynda’ or ‘Sverdlov’ surface ship ‘with a single hit from either weapon is low’. The Mark 24 was later modified to explode underneath the keel of a surface ship, creating a whipping effect that would break the ship’s back.153 The combined anti-submarine and anti-surface Mark 24 Mod 1 finally entered service in October 1980, but it too suffered from unreliability and shortcomings.
The Mark 24 Mod 1 was unable to reach modern Soviet deep-diving submarines. The Navy developed a modification kit which, when applied to the original torpedo, enabled it to go below its depth floor of 1150 feet to a crushing depth of 1450 feet, once it had gained acoustic contact. However, scientists and engineers in the Admiralty’s Underwater Weapons Establishment (AUWE) in Portland were still concerned that it was:
glaringly obvious that we are still a long way from meeting the threat. On the submarine side, the [Mark] 24-1’s 1450 ft will go nowhere near the limiting diving depth of the Soviets. Against surface targets, the [Mark] 24-1’s slow speed is inadequate against a fast ship, and of course the firing submarine is still tied to a bit of wire and so is restricted in manoeuvre; if faced with an A/S weapon such as the [Soviet] SUW-N-1 the situation becomes distinctly unhealthy.154
AUWE looked at further ways and means of modifying the Mark 24 so as to give it an adequate capability against deep submarine targets, by making its hull of a new and stronger material and by employing new welding techniques. AUWE hoped that this would increase the crush depth of the Mark 24 to 2500 ft. Early research had also started on the successor to the Mark 24 series, which the AUWE hoped to have ready by the mid-1980s.
The Navy was also exploring new weapon systems. The first was a private venture by Vickers, a Submarine-Launched Air-Flight Missile (SLAM) system designed to take out helicopters involved in anti-submarine warfare. In 1972, one of the last of the Royal Navy’s ‘A’ class submarines, HMS Aeneas, was loaned to Vickers to test a new weapon system consisting of six Short Blowpipe missiles mounted on a stabilized launcher, housed in a pressure vessel. The submarine would surface its fin, so that it was protruding out of the water, raise the launcher hydraulically, acquire a target by periscope and fire a missile, the whole procedure taking around 20 seconds. Trials indicated that the system had good capability against a helicopter out at 3 kilometres and some capability at 5 kilometres, particularly if the helicopter was hovering. But the system required manual guidance, the target had to be visual throughout the firing sequence and missile flight and there was no night capability. The requirement to expose some of the submarine for a short period was also a distinct disadvantage and many submariners regarded the SLAM as ‘over-rated … very ingenious, but it is a clumsy
short range, daylight only system. We are not about to fit it to our submarines’.155
The second new weapon system was a submarine-launched sea-skimming missile, known as the Under Sea Guided Weapon (USGW), intended for use as an offensive anti-surface ship weapon. By the mid-1980s, NATO expected in the event of war to have substantial difficulties countering the vast Soviet surface fleet, of which it expected over thirty heavily armed units to be deployed in the Eastern Atlantic.156 The requirement for the USGW rested primarily on the SSNs’ ability to operate against Soviet surface forces in areas where the enemy enjoyed air superiority, but it was also envisaged as a complement to the anti-ship capabilities provided by other maritime forces. Its covert deployment was regarded as of considerable tactical significance. Of the two possible contenders, the Hawker Siddeley Dynamics Sub Martel and the McDonnell Douglas Astronautics Company Sub Harpoon, the Royal Navy preferred the US Sub Harpoon on grounds of reduced development risk, timescale and cost. Sub Harpoon also had a number of operational advantages such as longer range, larger warhead, advanced state of development and a more assured in-service date.157 Ministers endorsed the proposals in September 1973 and negotiations with the US Government were opened to procure a UK variant known as the Royal Navy Sub Harpoon.
Royal Navy Sub Harpoon was a small rocket of about 15 feet, with retractable wings. It was housed in a capsule about the size of a normal torpedo which was embarked on board a submarine in the traditional way and stored in the Torpedo Compartment. The missile itself used a dangerous liquid fuel known as JP10 and special precautions had to be introduced and enforced for those tasked with handling the weapons, as well as those living in the Torpedo Compartment, as strict regulations had to be observed. Much thought and redesign of the existing weapons system in the submarines was also required. When firing Sub Harpoon, the submarine had to be kept level within very tightly controlled limits for pitch and heel and be steady on course. The weapon capsule was discharged from the torpedo tube by a slug of water, as if the submarine were firing a torpedo. The capsule would then shoot towards the surface and, on breaching, small charges would blow the capsule nose cone off, allowing the rocket engines to ignite and the rocket wings to deploy. The weapon would then hurtle up into the sky before returning down towards the sea, where it would skim along towards its target at a speed of about 550 knots using active radar to home in. A salvo of Sub Harpoons would normally be fired at high-value targets such as a task group’s replenishment ship, tanker or aircraft carrier such as the Kiev. Although reliable, a salvo was fired in order to saturate a target’s close-range defences.158
The 1970s also saw the introduction of new sonar equipment. The primary means of detecting Soviet submarines was through passive broadband sonar. The performance of Type 2001 sonar in the passive role was downgraded by the noise of water flowing over the dome that housed the sonar array. This meant that the submarine was limited to a low speed when it was required to detect or hold targets. A fibreglass dome was eventually fitted over the array, which markedly increased the ability to hold contacts at higher speed. But passive broadband sonar ranges were relatively limited (out to 30 miles was exceptional) in the North Atlantic, even in favourable isothermal conditions found in the winter months. This meant that in order to detect any contacts Royal Navy submarines had to be relatively close to them. In poor sea and weather conditions this could be notoriously difficult.
The problem was illustrated in October 1977, when HMS Superb, under the command of Commander David Ramsay, took part in Operation ‘Crusader’, a covert ASW patrol in the north Norwegian Sea designed to assess the operating environment and ASW coordination in the area, and to initiate trailing operations on transiting Soviet SSBNs should the opportunity arise. During the 23-day patrol Superb attempted to intercept four SOSUS contacts assessed as Soviet nuclear submarines, including one ‘Delta’, on patrol in the north and three – one inbound and two outbound – ‘Yankees’, transiting to their patrol areas. Despite setting up thirteen separate barrier tracks ahead of and across the predicted tracks of the four transiting Soviet SSBNs, Superb with its standard, but domed, Type 2001 sonar fit failed to make any definitive classifications.159 Like British and American submarines, Soviet submarines and surface ships were also becoming quieter. If the Navy was to maintain its lead in sonar detection further improvements would be needed.
In the late 1970s a new item of technology was introduced that dramatically improved the capability of the Royal Navy’s submarines to detect, classify and trail Soviet surface ships and submarines. The towed array consisted of a long length of neutrally buoyant, flexible snake-like wire with hydrophones embedded in it at intervals of up to 30 metres or more, which was towed at the same depth as the submarine.160 The arrays were sometimes kilometres in length in order to intercept long wavelengths of very-low-frequency noise radiated from Russian vessels and submarines.
In 1977, recognizing the need to bring towed-array sonars into service quickly, the Navy developed Sonar Suite 2024, consisting of a UK towed array feeding into an off-the-shelf signal processor of US manufacture. Although this interim sonar provided a step forward, it had limited all-round surveillance capability, poor data display facilities and rudimentary connections with the Submarine Command Team and the Action Information System. A separate project to develop an improved towed array and advanced signal processor known as Sonar Suite 2026 was initiated. As well as exploiting advances in processing technology, it was specifically designed to match UK Tactical Data Handling Systems.161
Early US towed arrays were flushed out from a sheath in a submarine’s hull, but this limited their length to that of the submarine. Later towed arrays, such as those used by the Royal Navy, were clipped on with assistance of a tug. Once the array was clear of the submarine, and thus the submarine’s self-noise, towed arrays could detect, locate and classify noise emissions from Soviet ships and submarines at long ranges. Emphasis shifted away from detecting broadband frequencies to narrowband frequencies, which the towed array could detect at great distances. Emissions from equipment inside submarines, such as reactor coolant pumps and generators known as ‘tonals’, were then used to aid the classification of a target. They could also be used to determine the course, speed and range of a contact by a complex technique known as target motion analysis.162 Mastering the use of towed arrays and target motion analysis required considerable skill and expertise. Submariners with backgrounds in mathematics, physics and chemistry thrived when using the complex mathematical formulae associated with narrowband tracking, but others found the new science difficult to master. ‘We got it,’ recalled Mark Stanhope, who in 1975 was a relatively junior officer in HMS Swiftsure with a background in Physics, ‘but it took a lot of others a long time.’163
The towed array significantly enhanced the performance of the Royal Navy’s nuclear submarines and gave the service a powerful new means of detecting Soviet forces. The first towed-array systems, the Type 2024, were installed on the new ‘Swiftsure’ class submarines at the beginning of 1977. One of the first to gain operational experience with the new equipment was HMS Sovereign during Exercise ‘Agile Lion’, which took place between 28 January and 3 March 1977. After exercising with HMS Walrus and HMS Churchill, Sovereign sailed to take part in a joint US/UK trail of a Soviet nuclear submarine transiting south from the Northern Fleet, later identified as a ‘Charlie’ class SSGN. The towed array allowed Sovereign to make a long-range detection of the Soviet submarine, well before it took over from the US submarine that was tracking it. Sovereign settled down for what turned out to be a 62-hour, 707-mile trail in a position just abaft the Charlie’s starboard beam and started experimenting with tactics to improve the trail and gain information on the target using the then largely untested towed array. Sovereign’s crew quickly discovered that the accuracy of narrowband bearings was a great improvement on that obtained by the standard sonar fit.164 The post-patrol analysis warned that:
despite the apparent simplici
ty of the target’s transit the effort required to simply maintain contact for hour after hour must be recognised. Continuously aggressive trailing techniques were absolutely necessary to keep up and out of the target’s stern nulls [immediately behind the submarine] yet clear of his bow arcs whenever he zigged or cleared stern arcs. It was considered vital that MSN UK-22 [Sovereign] was not counter detected and the desire to obtain acoustic intelligence at close range was initially suppressed for this reason. As familiarity with the target increased and his pattern of operations developed so did the target’s speed of advance. Once a classification of a Mediterranean bound ‘Charlie’ class submarine was the most probable and deep water reached the opportunity to close up for ACINT [Acoustic Intelligence] was lost along with the target. Considerable quantities of data were recorded which may provide a fund of useful information, and the ship’s command team gained a lot of experience.165
The towed arrays were so effective that Royal Navy submarines testing the new equipment tended on occasion to pick up Soviet submarines while they were conducting exercises. In January 1978, HMS Swiftsure was conducting an evaluation of the Type 2024 Towed Array, codenamed Exercise ‘Six Bells’, in an area west of Ireland with HMS Churchill acting as a target. Not long after starting the exercise Swiftsure detected a probable Soviet conventional submarine and interrupted the exercise to conduct a covert trail for a period of eighteen hours before intentionally breaking contact.166
The US Navy was also enjoying considerable success with its own towed arrays. On 17 March 1978, the USS Batfish, equipped with a 1000-foot towed array, intercepted a Soviet Yankee SSBN in the Norwegian Sea and trailed it for fifty-one hours, before losing contact on 19 March during a severe storm. On 21 March, firm contact was reestablished in the Iceland–Faroes Gap after a US P3 Orion Maritime Patrol Aircraft was dispatched from the US Keflavik airbase in Iceland, to home in on a SOSUS contact. Once the Batfish regained contact it trailed the Soviet Yankee for a staggering forty-four continuous days, the longest trail of a ‘Yankee’ class yet conducted by a US submarine. The Batfish observed the Yankee travel 8870 nautical miles, including a nineteen-day ‘alert’ phase, much of it 1600 nautical miles from the US coast. Just outside the range of its sixteen RSM-25/R-27U missiles.167