I am always happy to help.
And about the Mark 9, I skimmed through all the ship equipment files for you and on average, based on my knowledge and what the game files show, some ships gain the Mark 9's around 1943.
You will also see a new and much more effective weapon, the Hedgehog.
The hedgehog is a devastating area of effect weapon, it fires a large amount of mortar like rounds in front of the ship, and unlike the depth charges, these do not have a maximum depth, they just keep going and explode on impact with your sub and are so much morer accurate abd deadly the depth charge could ever be.
