I´t difficult to know if condors repport only convoys or single ships too.
Probably their crews see ships at sea and report it to command when they land. and some times the planes attack the ships with bombs.
Also the "girls" in the departure port or inteligence could repport the traffic to germany. The same of the french u-boat bases to british
I use the single contacts when they are near or if i can do a interception course using the nomograph. :|\
I pay bribes to the bdu and luftwaffe for single ships repports. :rotfl: