| The depth charge is the original dedicated ASW weapon. It was an extraordinarily crude weapon - basically a can filled with explosives and a fuze that detonated at a preset depth based on hydrostatic pressure. This was adequate in WWI as submarines did not operate at great depths. Developed by the Royal Navy in 1916, the quantities used per kill in WWI gave no appreciation for what would be required in WWII.
The USN began to develop a depth charge of their own in early 1917, which was too weak to be successful. After the U.S. entry into WWI they adopted the Royal Navy depth charge fitted with their own hydrostatic fuze. The final U.S. WWI depth charge could detonate at up to 300ft depth and carried 300lbs of explosives. There was little development between the wars except for a 600lb variant. At the start of WWII, depth charges were essentially the same weapon as from the end of WWI. Development concentrated on increasing the depth at which a submarine might be successfully attacked and improvements to the sinking speed of the depth charges. The Mk 9 became the main improvement over the Mark 6. This was teardrop-shaped, capable of detonating at 1000ft, and entered service in 1943. The early Mark 9s still did not yet sink sufficently fast enough. Lead ballast and fins modifications were made to speed sinking. These modifications were at the sacrifce of explosive power and it now carried only 200lbs of TNT. The US abandoned depth charges after World War II, preferring torpedos and ahead thrown proximity contact weapons. |
| Mark 6: An older depth charge that was cylindrical in shape, about 28 inches long and 18 inches in diameter. They contained 300 pounds of TNT. These were primarily used in racks but could also be fired from K-Guns. Mk 6 (Early War) Weight: 338 kg /745lbs Charge: 272 kg /600lbs TNT Sinking Speed: 2.4m/s/ 8f/s later mods (mid-1942) 3.7m/s / 12f/s Depth: 9 - 91m /30 - 300ft later mods (mid-1942) up to 183m / 600ft |  |
| Mark 9 and 14: These were the later type of depth charges and had a teardrop shape, with a weighted nose to increase their sinking rate and improve underwater trajectory. They contained about 200 pounds of TNT or of HBX and have the same overall dimensions as the 300 pound cylindrical charges. These were primarily used in K-Guns but could be used in racks with minor modifications to the tracks.
Mk 9 (Late War) Weight: ???? Charge: 91 kg / 200lbs TNT Sinking Speed: 4.4m/s/ 14.5f/s later mods (1944) 6.9m/s / 22.7f/s Depth: 9 - 183m /30 - 600ft |  |
| Patterns: Destroyer Escorts, and other vessels likely to engage submarines, carried depth charges. Generally, several charges are released in rapid succession to form a pattern in depth, width, and length, and thus increase the probability of destroying the submarine. The pattern is obtained by dropping some charges from release gear on the stern, and firing others abeam from projectors, with appropriate depth settings made on the charges before launching. See Also: K-Gun (Projector), Mark 10 (Hedgehog), and Depth Charge Racks. |  |
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26 November 1999 (mjs)
URL:http://www.dmna.state.ny.us/slater/weapons/dpthchrg.html