[UKönig]

I will admit, I do not use realistic torpedos. Reload times, yes, duds, no. I didn't come all this way to sink something only to be betrayed by my own equipment. It's a game that I am trying to have fun at, I don't like getting cheated by bad fish. If I fire and miss, or I get a premie I will accept that in due course. If I hit and the angle was bad and it results in a "knock" and not a "blast", I will accept that too. I just like to be able to trust my torpedoes. I get the odd 'deep-runner' but by and large the depth gear can hold my settings.
I settle for running the torpedo under the target and break its back/keel. I save two for each potential target, one, and one to be sure. I rarely use 3 or 4 on one ship. If I am forced to use 5 torpedos on one ship that I can normally sink in 1-2 hits, I get suspicious...
In any case, you can sink an aircraft carrier or a battleship with one well placed shot under the keel. Even so large a ship cannot survive against that kind of structural damage. If you set your torpedoes to 2-3 meters against a battleship, then you should be sending them against the armor belt. Set them to run under and that same armor belt is now useless. Ships can also degauss to lower their magnetic profiles. Originally intended for use against coastal mines but also worked against magnetic pistols, so the impact fuse was often still used.
It looks like you're going with the 'punch a hole in the side and let nature do the work', while I am trying to break the keel. I will vary shots as the situation changes, that's one of the things that is fun about this game, there are so many different ways to play it.