Hello Charles, Garth, et al,

You're neither the first nor the last to wonder about the destructive power of depth charges as were put to use in WWII.

As Mr. McDaniel points out, physics has a large role to play, but there are other factors which apparently form part of the equation. For example, a depth charge exploding in proximity to a sub where the conning tower might absorb a large part of the shock wave, might be sufficient to avoid a catastrophic hammer blow to the pressure hull itself. Of course, in such an instance, physics again come into play.

Garth's reference to 500lb charges may refer to something later than my time. My recollection of depth charges used by the Canadian Navy during WWII and I believe they were probably patterned after the Royal Navy experience, were for 300lb charges of Amitol, which believe me brother, packed a helluva wallop at any given depth!

I will relate one personal experience of a number where the principal weapon of destruction was the depth charge, sufficient to bring a U-Boat quarry to surface.

On the afternoon of April 14, 1944, northeast of the Azores, I stood on the bridge of HMCS SWANSEA (1500 ton River Class Frigate) while we were being directed in a creeping attack against U-448 (VIIc) by HMS PELICAN (1300 ton Sloop)

The Sub had been attacked earlier by shallower patterns by our ship and had gone DEEP (800ft.) Our speed was slow ( say 6 knots) when we had reached the proper position in advance of the sub to commence a continuous twenty-six pattern of 300lb Amitol charges, possibly six or seven seconds apart.

At that speed, the shock waves were very much pronounced with each detonation. I had experienced many depth charge explosions up to that time, but that was the first creeping attack, where a comparitively slow rate of speed by the attacking vessel was an essential part of the excercise. I recall feeling the shock througout my whole skeletal frame as each charge exploded.Many of our ship-board lights were burst and the passageways were covered in cork bits dislodged from the deckheads.

U-448 surfaced in less than a minute after the last detonation. And after an abbreviated period of shell fire, from both allied vessels, the German survivors commenced to abandon ship.

Coming back to your initial question, it was stated by one of the surviving officers that the seventh depth charge dropped by SWANSEA was probably a direct hit, because after it, they remembered nothing, and their actions in bringing the sub to the surface was purely automatic.

We will never know exactly how far from U-448's hull one or more of those charges exploded. Since Ober Leutnant Helmut Dauter commenced to surface somewhere after seven or more charges had been detonated, the explosions thereafter, since they were all set to 'DEEP' must have exploded somewhere below the U-Boat.

Eight days following our attack on U-448, in company with HMCS MATANE, where each of us discharged a shallow pattern in the vicinity of U-311, those unfortunates were so badly damaged as to never surface again! So, who really can say?

Not much by way of clarification to your querry, but those are my recollections.

Cheers to all!

Jim Campbell