The anti-submarine role required streamlining of hulls and removal of guns and other external fittings both to reduce radiated noise, making the boats more difficult to counter-detect, and to improve sonar performance. A number of Second World War submarines were also enlarged to be able to take greater sized and more powerful main motors. This programme in the USN was known as the Greater Underwater Propulsion Programme (GUPPY), which gave the boats a maximum submerged speed of 15 knots instead of the 8 to 10 knots previously. This increase in speed further improved their anti-submarine capability. The Royal Navy converted eight boats of the wartime ‘T’ class to GUPPY-equivalent performance.
In their urgent quest for higher speeds and performance — as from 1943 onwards their U-boats were losing the sea battle — Germany developed experimental boats propelled by a fuel which made its own oxygen. Several boats of the Type XXII class were built, propelled by engines fuelled with concentrated hydrogen peroxide (high test peroxide — HTP) which does not require air to combust, but the war ended before they could be deployed. Exploiting this German technology, in the late 1950s the Royal Navy built two 800-ton prototype submarines which were HTP-propelled. However, although the two boats built, Excalibur and Explorer, reached speeds of 26 knots dived, the HTP proved to be highly volatile. Many fires and minor explosions occurred, so much so that Explorer earned the nickname ‘Exploder’. Fortunately, this hazardous technology was overtaken and made redundant by the advent of nuclear power at sea; this would revolutionise submarine propulsion. However, it did not entirely eclipse the modern diesel submarine, which is still a very potent weapon in littoral waters and, of course, is much less costly to build and maintain than the nuclear version. Several classes of the West’s modern diesel boats are fitted with air-independent propulsion (AIP) using fuel cell technology. This can give them several days’ duration at slow to moderate speeds without the need to surface or snort. If the potential threat nations acquire similar technology for their submarines, these boats, being extremely quiet and having extended endurance with AIP, would present a very difficult threat to counter.
In parallel to exploring the use of HTP for propulsion, the Royal Navy also tested this type of fuel in torpedoes, but this dangerous experiment came to an abrupt and violent halt in 1955 when a HTP-powered torpedo exploded in the submarine Sidon. At the time of the incident she was alongside in Portland Harbour, a fact that probably mitigated the death toll, but thirteen of her crew were killed and she sank at her berth. In 2000 a similar explosion aboard the Russian submarine Kursk occurred whilst she was at sea; the Kursk was totally destroyed with the loss of her entire crew of 118.
In 1955 the world’s first nuclear submarine, the USS Nautilus became operational. Despite its public image, nuclear power was to prove a much safer submarine propulsion. The Nautilus introduced a revolutionary change in submarine technology and capability. Fast, manoeuvrable, virtually unlimited in range and with no need to surface or snort, paradoxically, the nuclear submarine was to become particularly potent in the anti-submarine role, and was to be accorded very high priority in the West’s defence expenditure.
The first Soviet nuclear submarines were commissioned in 1959, but their nuclear plants were much less safe than their American counterparts. The crews of the first classes experienced many accidents and were exposed to high levels of background radiation. In expanding their submarine fleet, the Soviet Navy developed a number of differing types, each with a distinct purpose, all of which had to be met and outclassed by the navies of the Western alliance. In particular, they built both nuclear and diesel submarines (abbreviated SSGNs and SSGs respectively) which mounted anti-ship missiles which had the specific role of destroying the West’s strike carrier forces. The earlier versions of these types had to surface to fire their missiles and, accordingly, were very vulnerable to attack when preparing for weapon launch.
As their nuclear fleet expanded, there were numerous classes and designs with little heed to achieving the benefits of commonality and standardisation. The Soviets pursued quantity rather than quality and their first-generation boats were very noisy and crude in design. Furthermore, their missiles used very hazardous liquid fuel propellant, essentially German V2 missile technology, always risky in a submarine environment. Additionally, their crews were mainly conscripts, often of varied ethnic and language backgrounds and on the whole were poorly trained. In summary, the Soviet submarine fleet was afflicted by a range of serious shortcomings which militated against safe operation and consequently a number of boat losses and major accidents were to occur.
In 1959 the United States Navy commissioned their first SSBN, the USS George Washington. She was armed with the solid fuel Polaris ballistic missile and was followed by forty similar submarines. These were built with an average construction time of less than two years in comparison to the seven or eight years it now takes to build this type of submarine. The Polaris programme was a tremendous technical and engineering achievement involving large numbers of highly skilled technicians and craftsmen and numerous American companies, both large and small, which collectively contributed successfully to the monumental effort involved. Because the Polaris missiles had a maximum range of only 2,500 miles, the boats were based in ports which were relatively close to their patrol areas, with facilities being established in the Holy Loch (Scotland), Rota (Spain) and Guam in the Pacific.
The establishment of American nuclear missile sites in Turkey was to the Soviet psyche a close pressing of its borders, a threat it found intolerable and which it countered by the establishment of launching sites for nuclear-armed missiles in Cuba. In turn, this produced a reaction in America, precipitating the Cuban Missile Crisis of 1962. This unequivocal nuclear threat to continental America produced an equally uncompromising response from Washington. President John F Kennedy imposed a naval blockade of the island of Cuba, aimed at preventing the Soviets shipping in the missiles and other arms. During the weeks of escalation of tension, the world stood at the brink of nuclear war. The manifestation of their worst fears in the holocaust of Mutually Assured Destruction appeared to people across the globe to be very possible. Eventually, however, Nikita Krushchev and his Politburo backed down and ordered their ships to put about and head back from whence they had come. The missile sites already built were dismantled and the world breathed again. As a quid pro quo, the USA disestablished their Turkish missile sites. However, it had been a dreadful warning, and called from the Americans leadership and coolness almost unparalleled in human history.
During the weeks of uncertainty and in response to the American blockade of Cuba, lacking substantial surface warships which were capable of operating at a long distance from the homeland, and realising that their nuclear submarines were not reliable enough to deploy at such long distance, Moscow sent four Foxtrot-class diesel submarines into Cuban waters. Each of these was armed with two nuclear torpedoes which they were authorised to use if attacked by American forces. All four boats were detected by US anti-submarine units and to coerce them to reveal themselves and surface, practice depth charges were dropped onto them. These charges had only a small amount of explosive, but on detonating under the water they made a loud report. In the dreadful conditions onboard the Russian submarines, which were entirely unsuited to operating in tropical waters with temperatures nudging into the 50s, oxygen levels low, and the propeller and sonar sounds of numerous anti-submarine warships above them, such explosions were very unnerving. One of the Foxtrot commanders seriously considered firing a nuclear torpedo at the harassing forces, but was persuaded by his political officer (at the time all Russian submarines carried an officer appointed by the Communist Party) not to do so. Had the submarine captain destroyed an American warship using a nuclear weapon, the inevitable American retaliation might have led to total war. This was the nearest the two Cold War superpowers came to a nuclear exchange.