Why pre-dreadnought superfiring turrets needed the right hull form

Why were more six-inch guns not mounted in superfiring positions on earlier warships, and would higher freeboard create excessive topweight?

The arrangement was possible, but low-freeboard ships had tighter metacentric-height and topweight constraints. Deeper-draft, higher-freeboard hulls made elevated turrets more practical and improved performance in rough seas.

The discussion separates the broad idea of one gun firing over a lower position from the later arrangement in which one complete turret is raised above another. Earlier low-freeboard ships left designers with tighter metacentric-height and topweight margins, constraining where heavy mounts could be placed. Deeper-draft, higher-freeboard hulls changed those limits, and the Virginia class demonstrates that a superimposed arrangement was technically practicable by the early 1900s. Higher freeboard also kept more of the ship usable above the waterline, an especially important advantage in rough waters such as the North Atlantic, South Atlantic, eastern Pacific, and Antarctic approaches.