Depth Charge - Effectiveness

Effectiveness

The effective use of depth charges required the combined resources and skills of many individuals during an attack. Sonar, helm, depth charge crews and the movement of other ships had to be carefully coordinated. Aircraft depth charge tactics depended on the aircraft using its speed to rapidly appear from over the horizon and surprising the sub on the surface (where it spent most of its time) during the day or night (using radar to detect the target and a Leigh Light to illuminate just prior to the attack), then quickly attacking once it had been located, as the sub would normally crash dive to escape attack.

As the Battle of the Atlantic wore on, British and Commonwealth forces became particularly adept at depth charge tactics, and formed some of the first destroyer hunter-killer groups to actively seek out and destroy German U-boats.

The shortcoming of the depth charge as deployed by surface ships was not the weapon itself, but how it was delivered. An attacking vessel would usually detect a submerged contact using its sonar (or in British parlance, ASDIC). However, to drop its depth charges it had to pass over the contact to drop them over the stern. As such, sonar contact would be lost immediately prior to attack, thus rendering the hunter blind at the crucial moment. A skillful submarine commander therefore had an opportunity to take successful evasive action. This situation was remedied by the adoption of the ahead-throwing "Hedgehog" weapon, which allowed contacts to be engaged at a "stand-off" distance while still in sonar contact.