ANTONY PRESTON, JOHN BATCHELOR
Among, the many experimental ideas was one for a submarine carrying two small motor torpedo-boats on deck in cylindrical hangars. Like the operation of aircraft this was an idea which looked better on the drawing board than it did to an anxious U-Boat commander worrying about the length of time taken to get things in and out of hangars, and it was quietly dropped. Likewise the 2,500-ton minelayers of the Type XA and a trio of aircraft-carrying 3,000-ton U-cruisers were abandoned, no doubt with a sigh of relief from the submariners.
British Olympus. The success of the prototype Oberon led to the introduction of six "O" Class submarines in 1926 for service in the Far East. They were the first of a series of similar boats which incorporated the lessons of the recent war, and although quite successful they suffered from having external fuel tanks which leaked oil. This, combined with their size, led to four of the six being lost in the Mediterranean in 1940-42
The standard sea-going U-Boat which evolved from this series of prototypes was Type VII. The first group, known as VIIAs, Were developed from a German design built in Finland but in turn the Finnish boat owed a lot to the old UBIII Type of the First World War. U27 was the first to be launched in 1936, and by the outbreak of the Second World War the improved Type VIIB was in service. The Type VIIC which followed had many improvements over the original A type, such as more powerful diesel engines and greater fuel capacity, and became the standard wartime type. By 1941 the first had been launched, and as the 600-odd which were built came very close to winning the war for Hitler and Nazi Germany, a closer look is indicated.
The Type VIIC U-Boat had a waterline length of 220 ft, a beam of just over 20 ft. and displaced about 770 tons on the surface. She was of fairly conventional design, with saddle tanks, four bow tubes and two stern tubes; her diesels drove her at 17 knots on the surface and the electric motors could produce 7,5 knots for a limited time under water.
Russian "K" Class. This class was also known as the Katyusha Class, and they were large ocean-going submarines with a heavy armament. Displacement: 1,390 tons (surfaced). Armament: Ten or twelve 21-in torpedo-tubes; two 3·9-in guns; two 45-mm AA guns
Although not an ideal type for the Second World War as if turned out, the Type VII series was simple to build and very handy. Its principal drawback was its endurance, 6,500 miles at 12 knots, which proved insufficient for extended operations, while its lack of internal space imposed extra burdens on personnel. British submariners would have been surprised to learn that their German counterparts regarded Royal Navy submarine accommodation as palatial. Despite these inherent problems the U-Boat Arm waged a most determined and ferocious campaign from the Arctic to the Indian Ocean in conditions ranging from merely, spartan to utterly vile.
At this point it is opportune to revert to progress in anti-submarine, warfare, for this had kept pace with the frightening increase in the submarine's efficiency between 1919 and 1939: First, the British Admiralty had learned the lessons of 1917, and convoy was to be their standard defense for merchant ships. Meanwhile, in 1918 a secret committee of scientists had been set up to investigate methods of detecting submarines, and their researches had resulted in the brilliant discovery that a sonic beam could be bounced off a submarine's hull and be measured to give a bearing and range. Known from the initials of its parental committee, the Anti-Submarine Devices Investigation Committee, ASDIC, worked on the simple principle of passing an electric current through a quartz plate. Although the Germans suspected its existence, they did not uncover the secret until details were captured in France in 1940.
British Sealion. In 1929 the first orders were placed for medium-sized patrol submarines, as the Royal Navy became aware of the need for smaller boats to work in Northern European waters. The problem of leaking fuel tanks was solved by putting them inside the pressure hull, and as speed and submerged endurance were not sacrificed the "S" Class was most successful. An improved version was put into mass production during the Second World War, making this class the largest single group of submarines built for the Royal Navy: more than sixty units were built over a period of fifteen years. Displacement: 735 tons (full load, surfaced). Armament: Six 21-in torpedo-tubes (forward); one 3-in gun. Speed: 13,5 knots (surfaced), 10 knots (submerged)
By 1939 the Admiralty had ensured that some 200 escort vessels were fitted with Asdic, and all anti-submarine tactics had been developed to make use of its remarkable properties. It led, however, to a dangerous under-estimation of the threat from submarines, and there were people in the Admiralty who talked of the submarine being a weapon of the past. Not only were there too few escort vessels for the amount of shipping to be protected, but the Asdic had its blind spots; it could not be used against a surfaced submarine, and at that stage in its development it could not hold the target when the searching ship passed overhead. Thus an attack with depth- charges always had to be carried out "blind".
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