That said, even if they were completely unarmored and in open air pits, I don't really see how it would be relevant. It was demonstrated repeatedly in WWII that naval gunfire was almost entirely ineffective at knocking out coastal artillery.
Thats because most coastal artillery in WWII was bunkered Japanese or late stage Atlantic Wall fortifications. However in WWI, the allies did silence the guns guarding the Dardanelles before blundering in a minefeild.
I agree, but the RN does have the strength to do both.Nor do I think in this scenario any Royal Navy ships would be attempting to duel the guns anyway - the focus would presumably be on the German transports attempting to cross the channel and their escorts.
Faulty assumption, the Germans had good success with the Scharnhorst and Gneisenua vs transports let alone barges. I've talked about how barges would be swamped, but with transports the big shells water hammers will cave in thier sides and allow as much water in as a direct hit.The general assumption now seems to be that the Royal Navy would not risk sending battleships into the channel to oppose a crossing - that only cruisers, destroyers and MTBs would employed.