Depth charges not doing damage at periscope depth?

[SubMate]

Originally Posted by Moonlight

Just to clarify things, where did you set your difficulty level, at the Main Menu or in the Office?.

Office, but I don't think there are any settings (at least in vanilla SH4) that allow you to change difficulty, in terms of the enemy.

I attacked an enemy task force earlier today, and surfaced just to verify that I take damage from guns, which I do. However the destroyers hunting me were depth charging random locations, and often reversed into their own charges, killing themselves (2 died this way).

Do mods such as FOTRSU make the game harder? I never have problems infiltrating or escaping convoys, and it is getting quite boring.