Hello again!
Well, this is how things went.
He found me a few more times, and then left after I managed to get away with the help of your advice. He never dropped any more charges, so he must have ran out.
Anyway, I used this time to catch up to the convoy, and sink two whale factories and one large tanker. The destroyer which never met me started dropping depth charges, but I hid from them by the debris...
it worked alright, but after time accelerating one of them disappeared.
they eventually left to go back to the convoy.
A grand success, even if it took a few hours of evading depth charges
(oops I did not take the advice of not moving rudder all the way... ill have to remember that)