If your to play this as true to life (sim) then the japanese never set there DC over 100ft until a US congressman let it slip during an interview about mid 43. Up until then the japanese thought the US subs were like there own and could only dive to 100ft or there abouts.
It wasn't until that slip by the congressman telling the press that the japanese dcs were having no real effect on US subs.
After mid 43 the Japanese started setting there DCs to over 250ft.
So if your to play as in the war, then up until this point Japanese DCs should not be set greater than 100ft.
Got the piece ....
Pacific Theatre
In the Pacific, Japanese depth charge attacks initially proved fairly unsuccessful against U.S. and Russian subs. Unless caught in shallow water, a U.S. submarine commander could normally dive to a deeper depth in order to escape destruction.
The deficiencies of Japanese depth-charge tactics were revealed in a press conference held by U.S. Congressman
Andrew J. May, a member of the House Military Affairs Committee who had visited the Pacific theater and received many intelligence and operational briefings. At the press conference, May revealed that American submarines had a high survivability rate because Japanese depth charges were fused to explode at too shallow a depth.
Various press associations sent this leaked news story over their wires, compounding the danger, and many newspapers (including one in Honolulu, Hawaii), thoughtlessly published it. Soon, Japanese forces were resetting their depth charges to explode at a more effective average depth of 250 feet. Vice Admiral
Charles A. Lockwood, commander of the U.S. submarine fleet in the Pacific, later estimated that May's revelation cost the United States Navy as many as ten submarines and 800 crewmen lost in action.
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