British battlecruisers normally shared the gun calibre of their contemporary battleships. Higher speed required a longer hull, more boilers, and more machinery, making that combination difficult when dry docks could not be enlarged. Hood and the Queen Elizabeths illustrate the size difference between ships carrying the same guns. The G3 example contrasts proposed 16.5-inch battlecruiser guns with 18-inch battleship guns because the designs had to fit existing docks. Gun calibre therefore reflected infrastructure and available funding as well as the ship's intended combat role.
Notable Point · 2:31-3:37
Why dock limits could change a battlecruiser's guns
Matching a battleship's guns at higher speed required a longer hull and more machinery, so fixed dry-dock dimensions could force a smaller armament.