Hi stbw
I am not aware of the 2 circles method.
You do not describe the method that you do not want to use
Is the convoy visible on hydrophne?
Is a radio message telling you of a convoy and giving you the co-ordinates?
Stoianm did a YouTube video where he intercepted a convoy just by receiving a radio message.
Post #37 Intercepting A Convoy Having Received BDU Radio Message By Stoianm
Peter