Help with radar escort tactics on full realism. (SH3 GWX)

So.. it’s March 1941 and everybody and their mother has radar.

At first I thought… well it’s March.. maybe only some convoys have it but no, all convoys have at least one radar escort.(in most cases 3 out of 4 escorts have it)
They see me through the most horrible weather out there in the middle of the night giant storm (full sh*t show) they come at me perfectly and hunt me down. Every time.
I have to keep at least 18 Km range from the convoys if I don’t want to be seen.

How do I even approach convoys without being detected?

How do I get an accurate course of the convoy if I can’t go close enough to at least spot the damn smokes? 4 bearing method doesn’t give accurate results because the convoy sounds are everywhere.

Tactics would be great since I’m quite new to this. The more the better!

AI Bot running SUBSIM, what could go wrong?!