Depth Charges and WWII Submarines: Damage Range and Efficacy

Introduction

The effectiveness of depth charges in sinking or damaging WWII submarines was a critical aspect of anti-submarine warfare. The Operational Research Section of RAF Coastal Command extensively studied the use of depth charges to determine the ideal conditions for incapacitating U-boats. This article delves into the details of how close depth charges needed to be to a submarine to cause significant damage.

The Operational Research Section's Findings

According to the Operational Research Section, the standard 250-pound depth charge proved effective when used with proper technique. These charges had a killing range of around 20 feet. The advantage of these charges was their lightweight design, allowing multiple to be carried and dropped on the target. An intervalometer controlled the distance between the charges by timing their release.

A key strategy in using depth charges was to attack the U-boat either on the surface or just after it had dived. Studies showed that the most successful depth charges were set to detonate at a depth of 25 feet to maximize their effectiveness. Additionally, the proximity of the detonation to the submarine was crucial. An instance recorded aboard the submarine Archerfish on May 18, 1959, demonstrated the impact. At a depth of 150 feet and 2,000 yards from the explosion, extensive damage to internal equipment was observed inside the pressure hull.

Proximity and Efficacy

The proximity of the explosion to the submarine was the determining factor for causing significant damage. For the depth charge to be most effective, it needed to detonate directly in front of the submarine. The shock wave from the explosion traveled upward, and it was the shock wave that caused the most damage rather than the explosion itself. In general, within 50 feet of the submarine, a depth charge was likely to cause considerable damage.

The effectiveness of the depth charge also depended on the submarine's depth and the explosive force of the charge. The optimal scenario would involve allowing the charge to sink to a position just below the submarine at the time of detonation. This position maximized the upward force cone of the explosion, which is where the most power was exerted and where the most damage could be inflicted. Explosions above or to the side of the submarine would cause shock and rock the boat but were less likely to produce deadly damage.

Conclusion

The use of depth charges in WWII anti-submarine warfare required careful consideration of both the submarine's depth and the explosive force of the charges. The proximity of the detonation, particularly in front of the submarine, was crucial for causing lethal damage. Understanding these factors helped improve the efficacy of anti-submarine operations and saved countless lives during the conflict.

Further reading on this topic includes the book Black May by Michael Gannon, which provides an excellent account of the turning point in the Battle of the Atlantic where these strategies proved crucial.