[Schwuppes]

Hi!

I have learned that in the later part of the war the BdU would set up a line of boats perpendicular to the known convoy lanes.... each U-Boat say 20 km apart or so.
If there was accurate intelligence they would set up the U-Boats right infront of an incoming convoy. The Germans also used surveillance aircraft to help find the convoys.

The boats would stay submerged most of the time and if they were "lucky" the convoy would come their way and they would be able to manouver into a more or less good attack position.
If you weren't in the right place at the right time you missed your chance.
It was virtually impossible to resurface and overtake a convoy because of allied air superiority.

However Most of the time the allies were able to divert the convoys around the U-Boats because of ultra (intelligence) intercepts.