Anti-submarine methods developed from pre-First World War ramming and hand-dropped grenades into purpose-built depth charges. Crews had to choose the charge depth and attack pattern while the target's exact position remained uncertain. ASDIC improved detection, and the Royal Navy had been refining it since the system entered production in 1922. It still performed poorly against surfaced submarines and forced an attacking ship to lose contact during the final depth-charge run. Better sensors reduced uncertainty without removing the geometric and timing problems of the attack.
Chapter · 10:53-12:52
From ramming to ASDIC and depth-charge attacks
The evolution from ramming and hand-dropped grenades to ASDIC and depth charges still left attackers with difficult depth-setting, pattern, and final-approach problems.