Q1: A battleship enters a seazone with a hostile submarine. The sub submerges.
Following the rules, the sub emerges after the combat (that doesn’t take place)
Who controlls the seazone after the battleship owners turn?
Is the sub able to raid the convoy zone in that seazone, or is it impossible, cause the battleship owner “won” the battle and controls the sea zone?
Q2: Does the sub emerges before the collect income phase of the battleship owner and is it able to raid the sea-zone of the battleship-owner?
Q3: A submarine enters a seazone with a hostile submarine. Both sub submerges before any round of combat.
Are both submarines are able to make convoy raids? (For example a UK-sub and a Jap-sub in SZ 37)
1: No power can “control” a seazone. That’s why you don’t mark it. The sub is able to raid, because it remains in the seazone during the collect income phase. Powers occupy a seazone, and a seazone can be hostile, but it’s never really “controlled”. A power can still place units in a seazone adjacent to its factory, regardless of how many enemy units might remain in that seazone (that may even be disrupting a convoy).
3: Yes, assuming each is present during their respective enemy’s collect income phase (when the disruption occurs).
“Submerging” is simply a term for the option to retreat but remain in the same seazone. It serves no other function, and it does not have any impact on any other phases of a turn. After combat, all subs are effectively no longer submerged.