A BC is quite fast while having strong air defence & attack. The DD even more so. Would a BC+DD fleet for Germany be a more efficient build than a BB+DD fleet if it's often (not always) going to engage carriers? I mean, the UK has allot of carriers...
First off, to reply to another post... in SF, surface forces could barely do jack to a fleet containing a single carrier. FtM, this is no longer the case.
Now, as to the original post...
I have done a LOT of naval fighting. My report is: Yes, BC-DD fleets (as GER) are more effective at anti-CV warfare than combinations with BB or CL.
That being said, I am ---most definitely not--- saying that "BC beats CV".
If you are going to honestly counter the RN (and later USA) CV fleets with BC, you need to make sure of a few things:
A) Keep your BC and DD engine tech as far ahead in research as you reasonably can. Other techs too of course, but this one is crucial.
A2) If you have "old ships", use them for *other purposes* than refilling lost ships. Anything more than 1 tech-level behind the fleet you are trying to "replenish" is going to likely hurt you more than help. If you have an entire fleet that's "getting up in years", switch it's active role to convoy raiding, shore-bombarment providing, or standing in the next seazone over from the actual fight to intercept any other enemy navies trying to get to the "juicy carrier" combat.
B) ALWAYS engage within rage of land-based air. Even if you out-speed the target CV fleet, their CAGs are going to do a lot to you while you are trying to shoot at the ships. By engaged the CAGs, at worst, the CAGs will end up with the "multiple combat penalty" for being engaged by INT at the same time, and at best, you can chase them off/destroy them, which (by definition) prevents them from harming your BC/DD fleets.
B2) If the air is clear of CAG, then send in some NAV of your own. Shooting the target from both air AND sea will speed up the "sinking process", and as well, if the enemy fleet is already engaged by 1 of your forces, the other one will have a 100% detection chance to enter combat with it
C) Even in ideal conditions, it will take a while to sink the ships; CVs (both ingame and historically, save for maybe a couple JAP models) are one of the more resillient ship types. You'll chase off to port/damage a lot more CV than you sink from full health. While sinking is always better, a CV is only a dangerous sea opponent if it's actually out in the sea. If you keep them locked in ports forever, that's 80% of a win right there. (for added fun, then launch an amphibious invasion against the port province while you have it blockaded... the fleet will try to move out to intercept the invasion, right into your waiting battlefleet, and usually then right back into port after taking a few hits ;p )