You know, even in SH3 they do sometimes lose contact with the convoy. I had something similar to what Markshot describes, was pounding a straggler with the deckgun when 2 of the convoys black swans come back to make me go away. eventually they gave up and went to rejoin the convoy, but they did so by matching the convoys course and speed.

this meant I could get ahead of them and attack the convoy that was short a rear and a flank escort, easy pickings.

so is this an exmaple of escorts losing contact, not knowing what to do and then returning to last known heading and speed?