HMS Furious and Yamato close the guide in its 18-inch grouping. The illustrated diameter is roughly the distance from shoulder to shoulder, completing the increase from Dreadnought's 12-inch starting point. The final joke again connects the projectile's width with the prospect of being hit by it.
Chapter · 1:10-1:25
HMS Furious and Yamato in the 18-inch comparison
The final comparison groups HMS Furious and Yamato under 18 inches and illustrates that width as roughly shoulder to shoulder.