refitted and recommissioned her, in November 1940, as Thunderbolt. As an epitaph to her 'previous life', she entered service with a diagonal rusty line on her hull that could not be hidden.
THE WAR YEARS
Under the 1940 War Programme came the decision to build nine slightly modified T Class submarines. These modifications were made in the light of experience gained with the first group of T boats, the main changes being in the number and disposition of torpedo tubes, the outer hull shape and the use, in most of the modified vessels, of electrically-welded rather than riveted construction. The latter change assisted deeper diving, improved the resistance to depth charge attack and enabled the shipbuilder
