If it were me, and this convoy seemed like pay dirt (ie, massive and could give up a lot of tonnage) i would head out to one side of it say about 15 KM out and do periodic hydrophone checks... always keeping in contact with them, plotting their last known position, plotting their estimated course, following them on the surface mostly only submerging to verify their position over and over again with the patience of a hunter.
and when the weather breaks, because eventually it will... move in like a shark and deal them a devastating and lethal attack!
but thats just what
I would do
