Convoy tactics in 44

I must say that now I'm loosing the itch... Lost my VIIC in late 43 in the Med (one DD made me to go too deep) so I've started a new campaign with VIIC/41 from Cobald. This time it's ok with planes, they don't bother me too much, if they are single my twin M42 does it's job. Schnorchel is useless while without radar warning my crew spots planes to late and its too late for anything than reloading my save so I'm doing the old way - surface/dive.

I've tried 2 times to approach a convoy but before anything escorts go straight at me (they have a perfect lock on me from 9km). Can't do anything as crawling underwater doesn't make sense. It's a very dark night, with my brightness high visibility is still low. If an escort goes straight at me he gets an eel but now they zig-zag while approaching. Also I would like to keep my cargo for fat merchants, enough of killing DDs...

Now for 4 hrs? I'm trying to loose a pesky american DD. Everything fails. Bold, depth and course changes, sneaking behind his back etc but everytime he circles he finds me again and again. He must have dropped 300 DCs... Maybe Bold 1 is the problem? Couldn't upgrade to v3 but hey. DDs were easy! Never needed to use decoys.

I'm pissed and tired just like my crew. Event can't shoot him as my tubes are damaged and need a whole day to fix em.......

Any ideas? Or should I start again with VIIB in 1939...