I noticed it was your first post after I answered:
Welcome!
We all love 1940 here, so glad you are playing it.
I just downloaded the europe map in triplea - haven’t played europe before… what are convoy zones and how do they work?
Thanks.
Convoy centers provide income to their original owner as long as that power retains control of them. When they are under enemy control, they provide income to no one. They can be taken control of by moving a warship (not a transport) into or through them in combat movement when they are unoccupied. When they are occupied, they can be captured by attacking and defeating the occupying force, if the attacking force has at least one warship remaining after the battle.
Thank you!