Tiger's 13.5-inch barbettes were about 24 feet 6 inches across, while the 15-inch Mark I mounting required roughly 30 feet. The diameter would have to grow by 5 feet 6 inches, or 2 feet 9 inches on each side. Tiger's beam was 90 feet 6 inches, only an inch narrower than the Queen Elizabeth class, which already carried 15-inch guns. Their similar beams give a first reason to investigate whether Tiger could accommodate the larger mountings.
Chapter · 0:37-1:32
Tiger's beam leaves room to consider larger barbettes
The proposed gun change requires wider barbettes, and Tiger's beam is almost identical to that of the 15-inch-armed Queen Elizabeth class.