@ TarJak
This is exactly what I missed, an increased probability of blowing up ships when hitting in the right place. When not, they may sink through flooding or not, its fine for me. But I saved and loaded in front of the King George V a few times, aiming and shooting at different places (for experiment). I never managed to blow the magazine up, like on the first try with 4 torpedoes fired right INTO the magazine (and ordering flank speed to turn my boat into a ramrod afterwards, with no effect *lol*)
About merchants: Tankers are modelled correctly I think, taking one hit and blowing up, or taking 2 or 3 if empty, because those things are about 10000 tons in displacement, this is OK.
What bugs me are the small/coastal merchants, like I said I everytime need 2 eels for them, no exception when I used that DM so far.