The Thermopylae was part of the British T-class submarines, the first submarines within the British navy where the fuel tanks were build inside the hull, to prevent that leaking fuel left a trace. This class was to replace the Oberon-, Parthian- and Rainbow-classes, although being about 450 tons smaller, they were superior to their predecessors, being better armed and fitted out with two more torpedo tubes. Original dimensions of this class 84 x 8,10m and a displacement of 1.597,15 tons surfaced and 1.326,9 tons submerged. The dimensions of this class after rebuilding 285’(between perpendiculars) x 26’7”x 16’ (maximum). When she was rebuilt, her hull was cut in two and lenghtened with an additional 12’. Armed with original 10-45mm torpedo tubes of which 8 in the bow and the other two in the sides and with 5 of the 10 tubes extern placed and further 1-101mm gun, taken 16 torpedo’s with them. When rebuilt the five extern tubes were removed and since then 4 tubes in the bow and 2 in the stern. On board were now 20 torpedo’s. Their crew numbered original 55, after the conversion 68 men The horsepower of 2 x 2.500 hp (diesel) and 2 x 1.450 ehp (electric) made a speed possible of 16.25 knots surfaced and 9.25 knots submerged. The Thermopylae was one of the last of her class built and profited of large modifications, especially in the electronics and the rooms for the rooms. In fact she was part of the eight boats of this class which were converted in the years 1956-1956. The Thermopylae was laid down at the Chatham dockyard 26 October 1943, launched 27 June 1945, completed 5 December 1945 and sold to be broken up 26 May 1970.
