Royal Navy planners estimated that two hits might be needed to disable or sink a major warship, while an ordinary wartime firing solution might yield only one hit in five. A ten-torpedo forward salvo therefore gave the boat a statistical chance of delivering those two hits. Later training and fire-control improvements raised hit expectations toward one in three and eventually one in two. The hull's unusual armament nevertheless reflected the earlier, more pessimistic calculation.
Notable Point · 2:48:24-2:49:41
Why T-class submarines carried a ten-torpedo bow salvo
The T class was designed to fire enough torpedoes to secure multiple hits on a carrier or capital ship.