of stowage within the pressure hull. It proved impossible to reduce the displacement back to 1,000 tons without unacceptable reductions to endurance, and the displacement was allowed to rise to 1,075 tons. After a slight reduction in the length and the fresh water diving requirement of the design, the final design was agreed upon in May 1935. On 24 June 1935, the designation "Repeat P" was formally dropped by the Admiralty, and it was decided that the submarines would all bear names beginning with the letter T. Finally, on 3 September 1935, the name was selected for the lead ship of the class. Final approval for the design was given by the Admiralty Board on 13 February 1936. The Vickers, Cammell Laird, and Scotts shipbuilding companies were invited to submit tenders on 5 December 1935, and on 5 March 1936, the contract for Triton was awarded to Vickers Armstrong under the 1935 Programme. Design The design of the T-class submarines was dictated by the requirements of an extremely large forward torpedo salvo capability and long patrol endurance for operations in the Pacific against Japanese warships, as well as the need to comply with various treaty restrictions. These extremely challenging requirements led to many compromises in the design. Operational experience before and during the war led to many alterations and modifications to the class, and individual boats often differed noticeably from each other. Hull and superstructure To accommodate the external forward torpedo tubes, most of the T class had distinctive bulbous bows. The original bow shape of the Group One boats adversely affected the speed while surfaced and two of the Group One boats had the external bow tubes omitted during refitting ( and , formerly Thetis), resulting in a finer bow shape. Group Two boats had the external bow tubes moved further back, allowing for a finer bow shape that ended the speed loss. They also had two of the external torpedo tubes reversed to face aft along with an additional rear torpedo tube, resulting in a characteristic hump. The final Group Three boats had the bows further fined and the casing around the conning tower and rear-facing torpedo tubes flattened, resulting in a smoother profile. Pre-war T-class submarines were of riveted construction. The riveted hull proved remarkably strong, with many of the T-class boats exceeding the rated diving depth of during combat. , survived a dive to on 23