That resistance bonus is whack. What's really hilarious is that the bonus applies regardless of whatever the incoming shell is, so you get 1900's Austro-Hungarian pre-dreads that can soak up multiple 20" shells. I'm honestly surprised the US isn't the best for that. The US has historically been ahead of the curve for ship design and construction, after all. The South Carolinas had better internals than Dreadnought herself and both them and the later Delawares were standouts for their all-centerline armament, handling the keel stress from that quite well. Later on all our treaty designs had high-tensile STS all over to reduce weight while keeping or even adding to integrity since it was quite superior to the usual structural steels and doubled as high-hardness homogenous armor.