Course SSE, WNW, ENE etcetera consists of the dot between for instance S and SW on your gradient disc (ruler).
It is pretty realistic that you get only one mention of a convoy spotted and a general course after which you have to decide whether to intercept or not, and do not know if the convoy changes course because that was never spotted.
I refuse to act on any convoy radio report over 200-300km away. That way I can generally always intercept, no matter how much time transpired between the report coming in and me reading it, provided it is less than 10 hours.
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