I am embarassed to admit that having played this game for almost a year and I still don't know the basics of approaching and attacking a convoy.
The main problems I face are:
1) Approaching a convoy: It seems that even though I am on a silent running or in a complete stop the escorts pick up my presence from kilometers away and start pinging me within minutes. I read some materials about avoiding destroyers and dog-leg approach, but I need a more elaborate explanations of it as I have trouble understanding the material.
2) Picking targets: Let's say I start with a good position (as in the last training exam). I usually get overwhelmed as to which ship(s) I should be targetting. I completed the training by using automatic targetting and destroyed the leading destroyer first before getting the rest with deck gun

. I know that would never happen in a real game. So I was wondering how you choose your targets. I have few ideas, but I don't which is the 'right' one:
-Pick 1 or 2 juicy ones, fire slavo on them and evade.
-Try to get as many as possible by firing 1 torp per ship then evade.
-If you have a guidance system, fire in a general direction and hope for a hit.
-All of the above, use whatever is necessary depending on the situation.
-Other.
3) The last problem I have is how after the first hit the convoys start moving in zig-zag pattern making it impossible for me to go for another target. Am I supposed to fire all my torpedos so that they all hit approximately at the same time?
Also, just for a reference: I was wondering if anyone completed the torpedos and convoy training exams sucessfully in 100% realism setting.
Any help or suggestions will be appreciated, thanks.