[Paul Riley]

As radar removes the previous invisibility of the UBoats at night,the night can still be useful,albeit you are submerged of course.How about engaging the convoy from the rear,using it's own noise to mask your own? increase speed ever so slightly and then penetrate when certain you are on a good course to fire a 90 degree shot at a chosen ship.You would run silent prior to penetrating,then run standard just as you are about to penetrate.
It also makes sense more going in from the rear due to the fact that their main focus of observation is to the front,and maybe a few degrees to the sides (correct me on this),so you may manage to sneak in better from the rear,get onto your chosen attack run,attack,then exit rapidly through the rear.