I don't think the torp will need 400-600 metres to reach it's preset depth. Perhaps you just had duds, you do get them if you have the option selected in the realism settings. Personally, I set the depth to 2 metres for escorts and cruisers and normally get a good result.
Nemo
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"I'm afraid there is no disguising the fact that King's obsession with the Pacific and the Battle of Washington cost us dear in the Battle of the Atlantic".
Sir John Slessor GCB, DSO, MC, DL
AOC-in-C Coastal Command RAF
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