Well looking back at naval tactics one for large ships like Hheavy Cruisers and Battle
Ships was to fire their large guns at the water to down Low flighing Torpedo
bombers, infact during one of the runs against the Bismarck the Bismarck's main
guns used this very tactic and almost downed one of the swordfish biplanes.

Perhaps BB size guns or perhaps 8" or higher whichever creates the extremely large
splashes could be made to down Torpedo bombers on runs? I always loved the
idea, I posted it on the forums not long before the site changed so might as well
bring it up.

It works by firing the guns into the water the huge splash of water from the shells is
enough to down almost any aircraft if they are unlucky enough to be near it.