British T class submarine

The Royal Navy's T class (or "Triton" class) of submarines was designed in the 1930s to replace the O, P and R classes.

Design and development

Design began in 1934 but was constrained by the 1930 London Naval Treaty restricting the total British submarine fleet to 52,700 tons, a maximum of 2,000 tons for any boat, and maximum armament of one 5.1 inch (130 mm) gun. The "Repeat P"s, as the design was originally called, were intended to be large and powerful enough to operate against Japan in the absence of other British naval units. This demanded a large boat with impressive firepower, and the eventual design had 10 forward-facing torpedo tubes and a maximum diving depth of 300 ft (91 m). The design was finalised in 1935 and on June 24 June the decision was made to drop the "Repeat P" designation and give all boats names starting with "T".

The lead boat, "Triton", was ordered March 5 1936 and ran her first-of-class trials in December 1938. Fifty-three T-class submarines were built before and during the war in three distinct groups, although there were minor differences between boats within the same group.

ervice history

T-class submarines fought in all theatres in the Second World War and suffered around 25 percent losses. They were particularly vulnerable in the Mediterranean, where their large size made them easily visible from the air in the clear waters, but they had much more success elsewhere.

After the war, all surviving Group One and Two boats were scrapped and the remainder fitted with snorts.

In the late 1940s and 1950s, most were streamlined for quiet and higher-speed underwater operation against Soviet submarines, in place of the anti-surface-ship role that they had been designed for. In January 1948, it was formally acknowledged that the main operational function of the British submarine fleet would now be to intercept Soviet submarines slipping out of their bases in Northern Russia to attack British and Allied merchant vessels. The following April, the Assistant Chief of Naval Staff, Rear-Admiral Geoffrey Oliver, circulated a paper in which he proposed that British submarines take a more offensive role by attacking Soviet submarines off the Northern Russian coast and mining the waters in the area. With the dramatically reduced surface fleet following the end of the Second World War, he commented that this was one of the few methods the Royal Navy had for "getting to the enemy on his home ground." [cite book | title = The T-Class submarine - The Classic British Design | id = ISBN 0-85368-958-X | publisher = Arms and Armour | author = Paul Kemp | year = 1990 | page = 127]

Much of the work carried out on the submarines was underpinned by results of measurements made using "Tradewind", which had been modified in July 1945-September 1946 to become an acoustic trials submarine, with external tubes and guns removed, the bridge faired, the hull streamlined and some internal torpedo tubes blanked over.

Starting in 1948, eight newer all-welded boats underwent extensive "Super-T" conversion at Chatham Dockyard. The modifications included the removal of deck guns and the replacement of the conning tower with a "sail", a smooth-surfaced and far more symmetrical and streamlined tower. An extra battery was installed, and a new section of hull inserted to accommodate an extra pair of motors and switchgear. This varied between 14 ft (4.3 m) in the earlier conversions and 17 ft 6 in (5.33 m) in the later ones. These changes allowed an underwater speed of 15 knots (28 km/h) or more and increased the endurance to around 32 hours at 3 knots (6 km/h). The first boats to undergo this modification were "Taciturn" in November 1948-March 1951, followed by "Turpin" in June 1949-September 1951. The programme was completed with the conversion of "Trump" in February 1954-June 1956.

The conversion was not entirely successful since the metacentric height was reduced, making the boats roll heavily on the surface in rough weather. This was alleviated in 1953 in those conversions which had been completed by increasing the buoyancy by raising the capacity of a main ballast tank by 50 tons. This was done by merging it with an existing emergency oil fuel tank. For the four boats remaining to be converted, increase in buoyancy was achieved by lengthening the extra hull section to be inserted from 14 ft (4.3 m) to 17 ft 6 in (5.33 m). The effect was to lengthen the control room and strict instructions were issued that this space was not to be used for extra equipment otherwise the improved buoyancy would be affected.

In the meantime, in December 1950, approval was made for the streamlining of five riveted boats. This was a much less extensive process with the removal of deck guns, external torpedo tubes and the replacement of the conning tower with a "sail" and the batteries replaced with more modern versions providing a 23 percent increase in power. The work was much more straightforward than the conversion of the welded boats and was undertaken during normal refit. The first riveted boat to undergo this modification was "Tireless" in 1951.

The last operational Royal Navy boat of the class was "Tiptoe", which was decommissioned on August 29 1969. The last T class boat in service with Royal Navy, albeit non-operationally, was "Tabard" which was permanently moored as a static training submarine at the HMS "Dolphin" shore-establishment from 1969 until 1974, when she was replaced by HMS "Alliance".

The last operational boat anywhere was the INS "Dolphin", formerly HMS "Truncheon", one of three T-class boats (and two S-class ones) sold to the Israeli Navy [cite web | url= http://submarines.dotan.net/tclasse/ | title = Israeli T-class submarines | work = Israeli Submarines | accessdate = 2006-10-29] - and which was decommissioned in 1977.

Another submarine sold to Israel, "Totem" renamed INS "Dakar", was lost in the Mediterranean in 1969 while on passage from Scotland to Haifa - a tragedy still remembered in Israel decades later. Although the wreck was discovered in 1999, the cause of the accident remains uncertain.

Group One boats

These fifteen pre-war submarines were ordered under the Programmes of 1935 ("Triton"), 1936 (next four), 1937 (next seven) and 1938 (last three). The boats originally had a bulbous bow covering the two forward external torpedo tubes, which quickly produced complaints that they reduced surface speed in rough weather. These external tubes were therefore removed from "Triumph" during repairs after she was damaged by a mine and "Thetis" during the extensive repairs following her sinking and subsequent salvage. Only six survived the war, less than half.

* "Triton" (sunk in the Adriatic on 18 December 1940)
* "Thetis" (sank during trials, was salvaged and recommissioned as "Thunderbolt"; sunk by the Italian corvette "Cicogna" off Messina Strait on 14 March 1942)
* "Tribune"
* "Trident"
* "Triumph" (lost, probably to Italian mines, on 14 January 1942)
* "Taku"
* "Tarpon" (probably sunk by German minesweeper "M-6" on 14 April 1940)
* "Thistle" (torpedoed by "U-4" on 10 April 1940)
* "Tigris" (probably sunk by German ship "UJ-2210" on 27 February 1943)
* "Triad" (sunk by gunfire from the Italian submarine "Enrico Toti" in the Gulf of Taranto on 15 October 1940)
* "Truant"
* "Tuna"
* "Talisman" (lost, probably to Italian mines, on 17 September 1942)
* "Tetrarch", the only boat completed with mine laying equipment (lost, probably to Italian mines, on 2 November 1941)
* "Torbay"

Group Two boats

These seven vessels were all ordered under the 1939 War Emergency Programme. The first, "Thrasher", was launched on November 5 1940. The external bow torpedo tubes were moved seven feet aft to help with sea keeping. The two external forward-angled tubes just forward of conning tower were repositioned aft of it and angled backwards to fire astern, and a stern external torpedo tube was also fitted. This gave a total of eight forward facing tubes and three rear facing ones. All Group Two boats were sent to the Mediterranean, only "Thrasher" and "Trusty" returned.

* "Tempest" (sunk by the Italian Spica class torpedo boat "Circe" on 13 February 1942)
* "Thorn" (sunk by the Italian Orsa class torpedo boat "Pegaso" on 6 August 1942)
* "Thrasher"
* "Traveller" (lost, probably to Italian mines, on 12 December 1942)
* "Trooper" (lost, probably to German mines, on 14 October 1943)
* "Trusty"
* "Turbulent" (sunk by Italian torpedo boats on 12 March 1943):"Turbulent sank over 90,000 tons of enemy shipping. She was depth charged on over 250 occasions by enemy forces hunting her. [ [http://www.royalnavy.mod.uk/server/show/nav.2558 Submarine History : Submarine Service : Operations and Support : Royal Navy ] ]

Group Three boats

Wartime austerity meant that they lacked many refinements such as jackstaffs and guardrails, and had only one anchor. Much of the internal pipework was steel rather than copper. The first Group Three boat was "P311", launched on June 10 1942. Welding gradually replaced riveting and some boats were completely welded, which gave them an improved rated maximum diving depth of 350 ft (107 m).

*Nine submarines were ordered under the 1940 Programme.
* "P311" (lost, probably to Italian mines, before her name "Tutankhamen" was formally assigned)
* "Trespasser"
* "Taurus" (To the Royal Netherlands Navy as "Dolfijn")
* "Tactician"
* "Truculent" (sunk in collision on 12 January 1950)
* "Templar"
* "Tally-Ho"
* "Tantalus"
* "Tantivy"

*Seventeen submarines were ordered under the 1941 Programme.
* "Telemachus"
* "Talent" (P322) (to the Royal Netherlands Navy as "Zwaardvisch")
* "Terrapin "
* "Thorough"
* "Thule"
* "Tudor"
* "Tireless"
* "Token"
* "Tradewind"
* "Trenchant"
* "Tiptoe"
* "Trump"
* "Taciturn"
* "Tapir" (to the Royal Netherlands Navy as "Zeehond (2)")
* "Tarn" (to the Royal Netherlands Navy as "Tijgerhaai")
* "Talent" (P337)
* "Teredo"

*Fourteen submarines were ordered under the 1942 Programme, but only five were completed.
* "Tabard"
* "Totem" (lost in accident on passage to Israel as INS "Dakar")
* "Truncheon" (later the Israeli INS "Dolphin")
* "Turpin" (later the Israeli INS "Leviathan")
* "Thermopylae"The other nine were ordered but cancelled on October 29 1945 following the end of hostilities:
* "Thor" (launched 18 April 1944 but not completed)
* "Tiara" (also launched on 18 April 1944 but not completed)
* "Theban" (P341)
* "Talent" (P343)
* "Threat" (P344)
* also four unnamed submarines (P345, P346, P347 and P348).

Transfers to Royal Netherlands Navy

* "Tijgerhaai" (ex-"Tarn")
* "Zwaardvisch" (ex-"Talent")
* "Zeehond (2)" (ex-"Tapir")
* "Dolfijn" (ex-"Taurus")

ee also

*United States T class submarine

Notes and references