[swdw]

Originally Posted by tater

Interesting, a quick test with a 33% increased DC hit vs a tambor a couple meters from the hull, and I was very much still in the game. I think for a 6m sure kill to be realistic, heck, even a 3m sure kill, the DCs might need to be very very much more powerful.

tater

Hi again, posted this in the 1.3 patch and Japanese ASW topic, then saw this thread:

from http://www.submarine-history.com/NOVAthree.htm
by Cpt Brayton Harris USN (ret)

1940
U. S. Navy ran depth-charge tests against an operational submarine (for most of the test, moored underwater without crew). They found that 300 pounds of TNT was not very
effective; the explosive charge was doubled to 600 pounds.

(later dropped to 400, when they added a lead weight for faster sinking)

I do think you are correct in the navy thinking along those lines prior to 1940 and that line of thinking may have been derived from the DC tests on the USS G-1 in 1921.