Depth Charge Damage

CDR Resser · 04-27-08, 07:08 PM

I ran across this item while reading CMDR John Alden's The Fleet Submarine in th U.S. Navy on pgs 82-83. It concerns experiments that were performed on several of the classes of fleet boats. If this info had already come to light, I apologize for repeating it.

The tests were set up with the submarine cruising slowly at normal periscope depth of sixty feet past an explosive charge of 300 pounds of TNT moored at the same depth and tethered to a marker buoy and flag on the surface. An electric firing cable ran form the depth charge to the submarine rescue vessel Falcon (ASR 2) anchored about half a mile away. Navigating from fixed landmarks, the submarine crew plotted a course that would pass the buoy at the prescribed distance, initially 500 yards....According to one observer, the atmosphere on the Tambor was noticeably tense once the signal was fired because if anything went wrong with the steering gear and the submarine veered closer to the depth charge it would go off before another smoke bomb could be released. At the time no one knew much about the effects of exploding depth charges and the was considerable speculation that a submarine would be crushed like an eggshell as much as a mile away.

The first explosion was set off as planned on 20 December 1940 and, to everyone's surprise, caused no damage at all. A report to the Bureau of Ships described its effect as a "sensation similar to slamming of a watertight door or the 'flopping' of a kingston valve. Sharp metallic jolt. Not very intense." The second shot at 340 yards seemed to be about three times as intense as the first and produced more noise, a lateral displacement of the boat, and considerable shaking and vibration. At 275 yards the third explosion seemed to have not quite double the intensity of the second, and caused minor damage and a fuel oil leak fron the vent of one tank. For tests closer than 100 yards from the explosive charge, the crew was removed from the submarine while further tests were run with the boat moored. After each shot the Tambor was raised, inspected and repaired before being subjected to the next explosion. Whenever a problem was discovered, corrective measures were taken to avoid a recurrence of the same failure. In this way the range was gradually closed to 100 feet. Although no damage was suffered by the hull itself, so many internal items were damaged that the tests were terminated at this point....(Another series of carefully controlled tests was conducted on the Dragonet (SS 293) in 1944, in which explosive charges were set off as close as 75 feet from the hull with only minor damage.)

This information seems of importance not only for damage modeling, but also tactically. Realizing that you only need to move a short distance to minimize the effect of depth charges.

Respectfully Submitted;
CDR Resser

04-27-08, 07:08 PM	#1
CDR Resser Lieutenant Join Date: Mar 2007 Location: Submerged ahead Posts: 252 Downloads: 72 Uploads: 0	Depth Charge Damage I ran across this item while reading CMDR John Alden's The Fleet Submarine in th U.S. Navy on pgs 82-83. It concerns experiments that were performed on several of the classes of fleet boats. If this info had already come to light, I apologize for repeating it. The tests were set up with the submarine cruising slowly at normal periscope depth of sixty feet past an explosive charge of 300 pounds of TNT moored at the same depth and tethered to a marker buoy and flag on the surface. An electric firing cable ran form the depth charge to the submarine rescue vessel Falcon (ASR 2) anchored about half a mile away. Navigating from fixed landmarks, the submarine crew plotted a course that would pass the buoy at the prescribed distance, initially 500 yards....According to one observer, the atmosphere on the Tambor was noticeably tense once the signal was fired because if anything went wrong with the steering gear and the submarine veered closer to the depth charge it would go off before another smoke bomb could be released. At the time no one knew much about the effects of exploding depth charges and the was considerable speculation that a submarine would be crushed like an eggshell as much as a mile away. The first explosion was set off as planned on 20 December 1940 and, to everyone's surprise, caused no damage at all. A report to the Bureau of Ships described its effect as a "sensation similar to slamming of a watertight door or the 'flopping' of a kingston valve. Sharp metallic jolt. Not very intense." The second shot at 340 yards seemed to be about three times as intense as the first and produced more noise, a lateral displacement of the boat, and considerable shaking and vibration. At 275 yards the third explosion seemed to have not quite double the intensity of the second, and caused minor damage and a fuel oil leak fron the vent of one tank. For tests closer than 100 yards from the explosive charge, the crew was removed from the submarine while further tests were run with the boat moored. After each shot the Tambor was raised, inspected and repaired before being subjected to the next explosion. Whenever a problem was discovered, corrective measures were taken to avoid a recurrence of the same failure. In this way the range was gradually closed to 100 feet. Although no damage was suffered by the hull itself, so many internal items were damaged that the tests were terminated at this point....(Another series of carefully controlled tests was conducted on the Dragonet (SS 293) in 1944, in which explosive charges were set off as close as 75 feet from the hull with only minor damage.) This information seems of importance not only for damage modeling, but also tactically. Realizing that you only need to move a short distance to minimize the effect of depth charges. Respectfully Submitted; CDR Resser __________________ Holy Equestrian Order of Saint John Moses Sometimes, in war, there is an inverse moral. The greater the performance, the harsher the consequence. R.H. O'Kane Last edited by CDR Resser; 04-27-08 at 07:21 PM.