A twin 13.5-inch turret weighing about 600 tons is compared with a twin 15-inch turret weighing about 770 tons, despite broadly similar operating requirements. Scaling this relationship toward 20 inches means designing for the static weight of the mount, the force of firing, and shifting weight as the turret trains. Even nominally identical turrets can have small differences in balance, and the fact that they do not remain on the centreline makes the hull's handling and stability part of the gunnery problem. Calibre therefore cannot be scaled independently of turret machinery, hull structure, and the ship's operating characteristics.
Chapter · 8:38-10:50
A small calibre increase drives a much heavier turret system
Comparing 13.5-inch and 15-inch mountings shows how rapidly turret weight, recoil loads, and balance problems grow as gun calibre increases.