diesel engines fitted to the majority of the T class proved to be very reliable engines, even if they were less advanced than the diesels used by the German U-boats. The engine could continue running even if one cylinder failed by disconnecting the cylinder from the crankshaft. The 12 boats completed at the Royal Dockyards fitted with Admiralty diesel engines proved equally reliable, even though the engines were somewhat more complicated than the Vickers ones. In contrast, the MAN diesels proved to be rather troublesome. In particular, the MAN diesels were built under license, and once the Second World War broke out in 1939, technical support from the German MAN company immediately stopped. By 1943, only two of the T-class boats with MAN engines were left ( and ), and they were relegated to training use. Even when the Royal Navy in the Far East was facing a critical submarine shortage in March 1944, Tuna was rejected from being sent there due to her untrustworthy foreign engines. The Cammell Laird Sulzer 2-stroke engines received mixed reviews; some boats like and were perfectly satisfactory, while the engines caused problems on others. They were insufficiently engineered for running at full speeds, and tended to crack the cylinder rings and blocks. Submerged propulsion was provided by a 336-cell battery driving two Laurence Scott electric motors. These provided an endurance of 48 hours at or only one hour at the maximum submerged speed of . The battery proved vulnerable to shock damage from depth charge attacks, and this contributed to the loss of in 1942. She sustained depth charge damage from the that ruptured her battery tank and filled the submarine with chlorine gas, forcing her to surface and eventually surrender. This problem was resolved by strengthening the battery compartment and fitting rubber shock absorbers. In contrast with Tempest, the modified survived a prolonged depth charge attack from Japanese escort vessels, which rendered her hull a constructive total loss but inflicted no damage to her battery cells whatsoever. Weaponry Torpedoes It was expected from British work on ASDIC that other nations would develop something similar for submarine detection. In the face of expected enemy anti-submarine measures any attack would probably have to be made at long range without the aid of the periscope, using only ASDIC. To counter the resulting inaccuracy, a large salvo of at least eight torpedoes would be needed. British operational