I was shadowing a convoy recently and I was on perfect prallel course to wait for dusk. Well suddenly the lead escort turns straight at me and I wonder if he saw me or not. Well soon enough I see the rest of the convoy turn at me too but that course change was rather severe. A real surprise. But the good news is that the major course change turned it into an Atlantic convoy when it was looking like a Gibralter convoy.
Convoy course changes are such a pain, especially since it takes so much time to plot the new course and line up abreast. That's usually an hour or two of real life gone! And not even an attack.