Eighteen inches is presented as a plausible practical ceiling for battleship guns, although at least one navy might test a 20-inch weapon. Whole battle lines would not be built at that scale. Such ships would be rare fleet flagships or prestige super-battleships, perhaps one or two per navy, while more numerous 16- and 18-inch designs performed most capital-ship work. Fisher's HMS Incomparable concept is offered as the Royal Navy counterpart to the American Tillman maximum-battleship studies. The comparison separates technological possibility and prestige design from a sustainable force structure.
Notable Point · 2:00:36-2:01:15
Why 20-inch guns would belong to exceptional flagships
A speculative gun-calibre hierarchy reserves 20-inch weapons for one or two prestige super-battleships while 16- and 18-inch ships perform most fleet work.