sail round til i find an enemy boat then get close and fire .. and miss...
If you turn all the realism settings down in the vanilla version, you CAN actually play it a bit more action like, but what can I say, it's still a submarine game.
Lil fun fact that screws over most action style players, I guess:
IIRC the manual isn't very clear about opening torpedo tubes, and I think I remember the original icons in the lower left of the screen dont include "open tube". Do they? Standard hotkey is "q", but boy, I had to look for that.
If you dont open the tubes prior to firing, chances are, the torp will be off a few degrees, because of the delay. Even if you have the weapon officer calculate your solution, even if the TDC is set to update AoB dynamically, the firing solution from the second you pushed the launch button will be entered in the torpedo, not the correct one from the moment the torp leaves the tube.
So if you dont pay attention to this little detail, you'll miss a lot of shots.
and then get sunk
If I remember correctly, the manual of vanilla isnt all that clear about how to avoid/evade destroyers. I guess, that's something you'll have to learn yourself, since it's rather tricky, anyway. No amount of explaining can probably replace "havin it tried a few times".
IIRC the vanilla destroyers are rather easy, but the GWX ones, especially later in the war, will make you work hard for your money. For instance, you might even consider not going near any armed contacts post 1940 when you dont have at least 250 meter of water below your ass
Stuff I learned so far (and only managed to act correctly in 3 early war destroyer encounters so far): As soon as they noticed you, get the fudge out of dodge. The sooner you notice you're noticed, the better. Dive, wait til you're out of sight, and then change course a bit. Go as deep as possible as soon as possible. The VIIB or whatever you start with comes with 60 meter guarantee, if you dive the last meters slowly and the boat is in a somewhat acceptable condition, you can hang around 200-220 all day long. If you're lucky, the destroyer has to start it's search where you left sight, sometimes that's enough to get out.
Staying silent is a given, but it's a hard decision: when the depth charges are dropping close to you, you should probably go flank speed and turn, when you took damage, you probably HAVE to pump and repair unless you want to drown, but other than that it's silent running all the way. Oh yeah, with the exception of you knowing when you are where the destroyers cant hear you, ie, behind their own propeller sounds, then you can crank those engines up all the way. I probably dont have enough situational awareness to do that with more than one enemy around.
If you can help it, turn the boat in a way so the enemy gets only a slim profile of you, should he be working the sonar to get to you. Can be a hard decision also, because that means two things: you either run straight at the destroyer, which can be bad for health sometimes, or straight away from it, which means you put it in a deaf spot for you, ie, you're going to lose contact bearing for some time, which may or may not matter.
tl;dr, shallow waters get you killed almost every time, because diving under their sonar is the most reliable way to gtfo. (iirc that means more than 50 meters early war, and up to round 150 late war... and I havent even encountered/worked with and against radar...)
Something else:
Yesterday I had some sort "epiphany". Even if I play this because of my trig fetish, my brain is old and rusty. School is almost 15 years back and my maths training in my free time is very limited these days.
But yesterday it occured to me, how much fun you can have once you know how fast the targets in a convoy are going and what course they have. Because you can predict, when EVERY ship in this convoy will have an AoB of 90° to you. You dont even have to turn your friggin uboat perpendicular to their course, well, you should try, but if you'Re a few degrees off, who cares!
You can just tell the TDC "when the enemy ships pass me at x°, the AoB will be 90°". Then you put your periscope exactly on that spot, and set the TDC on auto update (that has nothing to do with realism settings, thats just a function of the TDC you always have) and adjust target speed.
Apart from the depth and pistol settings you should now have a usable firing solution for almost every ship in that convoy. Seriously, you should just be able to turn the periscope where you want to fire, and that's where the torpedo should go. At least as long as the targets dont go into alert mode or you dont try to fire in an angle that goes to hard away from 0° bearing.
Well, the theory works fine, in reality I was a tiny bit off with a few shots, but quite frankly, this was probably just sloppy data gathering. When I tried the same trick but have my weapon office calculate the initial shot (ie, get 100% accurate data) and fired the other 3 on different targets just by turning the periscope and have the TDC on "1", I hit every single torpedo, so I guess it IS actually supposed to work that way.
edit: and to be honest... always working with the 90° AoB because it's easy, that'S just lame. Calculating the AoB for every given bearing, once you know the exact target course, should be childs play. But as I said, rusty brain. However, I just started to figure it out, instead of just looking it up.
But while I wanted to dig up an illustration for the triangle in question, I stumbled upon this
I guess, that's also a way to do it
However, I wouldnt know how to measure "perceived length" quicker and more hasslefree than target course. Well.... actually I guess I can think of a way, but that would require me to get target speed, (which I have to do sooner or later anyway) and it would be awfully inaccurate... but it COULD work, especially since you have this little ship identification booklet, that gives you actual ship length, if you id'ed the target correctly.
edit2: and since this is remembering me of school, and ym maths lessons come back... glancing at my post, I should probably review english grammar rules about commas
Applying the same rules as german (and mixing them up with the little I can remember about english) to place em probably doesnt work all that well.
edit3: holy batman wall of text, sorry bout that.