I managed to break into my first convoy today.
I've been pushed under water early most of the time or the Zig Zagging saved them.
This battle was pretty tense, the Convoy got airraded 2 times. And a big 18.000 T tanker that ate 2 torpedos espcaped because I ran out of torpedos.
Result 4 ships sank.
Managed to finish of some lone ships on my way back.