I agree that the depth of DC's is too acurate to be real. More so if you keep in mind that neither Hydrophones nor ASDIC can directly give the enemy any information about your boat's depth.
With hydrophones alone, it would take three different ships to triangulate your position (not an easy thing to do). With ASDIC it would still take two. I hate it when a single destroyer is capable of dropping DC's right at your depth without error
I guess the devs made the game impossibly hard in this aspect to compensate for the fact that the game is too easy in others
