Thanks - sorry I was going to post on the vid but my google account appears to be my real name which I can’t seem to change easily and I don’t really want to paste that all over YouTube. So did on A&A.org instead.
I understand what you are saying (that is a carrier only counts as ‘with planes’ if it is already in the SZ by virtue of being an ally’s ship - if this is the case then the rulebook needs to spell that out a lot better!). I’ve also gone back to the globalwargame.com FAQ and looked at the CAP questions again.
The best CAP thread is the one with 9 answers entitled, ‘How to Hunt Submarines Convoy Raiding’. The last answer on there is the most relevant although it still seems a little ambiguous to me, but appears to imply the interpretation you have provided could very well be correct.
http://www.globalwargame.com/www/question/how-to-hunt-submarines-convoy-raiding/?ans-page=2
So basically whilst the rulebook would appear to state to me that you either have to send in a plane on CAP or a carrier with planes to attack a submarine for one round of combat (before it gets the opportunity to submerge regardless of what you do), in actuality you always need a plane on CAP.
Don’t suppose you could PM me Doug, or Will’s email so I can ask them to set me up an account on their website and try and clear this up once and for all?