Quote:
Originally Posted by Fidd
Based on memoires of surviving submariners from WW2, DC's seem to be very much too effective, with a very brief period in which the escort persists with hunting and attacks. Boats often reported 50-100 DC's being expended on a single u-boat plus 2-4 barrages with Hedge-hogs. The effect of DC's was fairly often a loss of depth control, as even-though the misses were far enough away to only cause minor damage, the effects on the u-boat's bouyancy at any given instant could be profound, especially with charges that exploded above or below the u-boats depth. This "dynamic-instabilty", ie instability caused by movement of the boat, magnifying tbe effect of any brief changes to the water-pressure or aeration of the water-column above the boat, could result in either the boat passing or approaching crush-depth or accidentally broaching the surface.
So, IMHO, DC attacks (as opposed to pinging, should be far more numerous but far less effective. This would also allow for progressive damage to be fixed by the crew when more detailed damage models follow.
Self evidently, we cannot have escorts prosecuting attacks for hours, so there's a balance to be struck. Personally I think DC attacks should last for 30-40 minutes.
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well that is an oversimplification, the reality was a lot more complex.
for example:
1. sept. 14, 1939: 2 DDs working as a team find and attack U-30. Sonar conditions were good. Attacks were delivered over 6 hours. U-30 received extensive damage, 2 torpedo tubes, engine room valve, 1 diesel engine out and the other heavily damaged, flooding took the boat down to 472 feet. U-30 escaped;
2. sept. 14, 1939: 3 DDs working as a team find and attack U-39. Sonar conditions were good. 12 depth charges were dropped in 3 attacks at depths of 100 to 500 feet. Batteries were damaged, lighting was knocked out, valves were cracked, chlorine gas was released when sea water entered the batteries, electric motor was knocked out, U-39 surfaced and scuttled. Attack lasted 20 minutes;
3. sept. 17, 1939: 2 DDs attack U-29 over 4 hours expending all their DCs. U-29 was damaged, but escaped;
4. sept. 20, 1939: 4 DDs hunt U-27 over a period of 2 hours at night losing and regaining contact several times. U-27 goes "deep" to 393 feet and orders silent running. 5 attacks are done dropping 25? DCs at depths of 100 to 250 feet. U-27 suffers extensive damage over the course of these attacks: bent propeller shaft, "series flooding". After 2 hours, U-27 tries to escape on the surface, but is caught and scuttles;
5. oct. 13, 1939: 2 DDs hunt U-42. U-42 goes to 361 feet. The 1st DC attack ruptures the aft ballast tank, the U-boat starts sinking backwards at a 45 degree angle. Crew is obliged to surface and scuttle;
6. oct. 14, 1939: 4 DDs hunt and attack U-45 which is sunk with no survivors;
7. nov. 29, 1939: 3 DDs hunt U-35. U-35 goes "deep" to 229 feet. 3 DC attacks are carried out with DCs at 250 feet. U-35 diving planes are jammed, aft ballast tanks and fuel line are ruptured, Boat is at a steep up angle and unable to regain control. U-35 surfaces and scuttles;
8. nov. 12?, 1939: 2 DDs attack U-49 delivering a "punishing depth-charge attack". The boat is driven down to 557 feet, periscope and all 4 forward torpedo tubes suffer unrepairable damage, but U-49 escapes. Note that this occur in weather which was "hideous",i.e. a storm;
9 and 10. nov ?, 1939: DDs (number unknown), escorts of convoy Sierra Leone 7 attack U-41 and U-43. U-41 is held down for 20 hours, but escapes with light damage. U-43 is "severely damaged", but also escapes;
11. dec. ?, 1939: DDs (number unknown) attack U-47, but attack is "desultory" and U-47 escapes undamaged;
so first 11 attacks of the war, 5 U-boats sunk, 3 heavily damaged, 2 w. light damage and only one undamaged.