@thatonekid:
this is not the case, each sub can disrupt 2 ipcs PER POWER is what gamerman is refering two, not two per tt.
so if you had 1 sub in z97 it could disrupt 2 for it and 2 for ger.
That’s right. Basically, as per Page 22 of the Europe manual, during your collect income phase you check (all players check) for convoy disruptions. On each power’s turn, a single enemy warship can disrupt only 1 IPC of income (subs are 2 IPCs).
Therefore, 4 Allied subs in Z97 would disrupt 8 IPC’s of Italy’s income if Italy controls territories bordering Z97 that add up to 8 or more IPC’s of income. Then, on Germany’s turn the check would be made again, and if Germany controlled Yugoslavia and Greece, Germany would also have to subtract 4 IPC’s of income on her turn. So in this manner, 4 subs would be doing 12 damage per turn. 8 to Italy, and 4 to Germany.