Lets say the Japanese decide to send the Yamato to the Guadalcanal campaign. Instead of a jumped-up pre-WWI era battlecruiser, its the planets latest BB which faces South Dakota and Washington.
I suspect that South Dakota is a goner, OTL she was hit 3-4 shells from Kirishima which did not penetrate but destroyed her radar and electrical systems.
No way she is taking a comparable number of hits from Yamato and living to tell the tale.
Washington opened fire on Kirishima before the later even knew she was there. Yamato had warning radar, so thats not likely and she had better fire control than her colleague.
Washington is FUBAR'ed at the very least.
Four 18" hits are going to badly hurt South Dakota, but they're unlikely to sink her. Taking it hit by hit, 14" hit #1 was a high-explosive shell to the bow above the waterline. That'll make more of a mess, but it's unlikely to be catastrophic. 14" hit #2 hit the radar plot and was a Type 3 IS shell; again, the larger 18" shell is going to demolish more stuff, but the location and shell type mean catastrophic damage is again unlikely. 14" hit #3 was an AP cap and windscreen hitting the outer shell, and then spraying either her below-water hull or upperworks with shrapnel. Again, unlikely to cause catastrophic damage, in this case because an AP cap and windscreen just plain aren't doing much more damage. If it did cause underwater damage there would be more flooding, but shrapnel isn't likely to cause catastrophic flooding, either.
Then we get the last, and that's the only 14" hit that would support your assertion. That was a direct AP hit on the barbette, which got bounced. Needless to say, it's very unlikely an 18" AP shell is getting bounced. So it punches through and detonates, disabling the turret, and lighting afire charges in the hoists. Sadly, this is
also unlikely to be catastrophic. American propellant was famously insensitive; Boise survived a shell directly introducing itself to one of her magazines, for Pete's sake. It tends to burn rather than explode.
Of course, random chance could mean better hit locations with Yamato, and given the last 14" hit happened while Kirishima was on fire from getting bushwhacked by Washington, she could conceivably also get more hits. But just the original four aren't sinking South Dakota.
Washington, meanwhile, is still going to bushwhack Yamato. Yamato doesn't have radar; she only got a search set installed in 1943. And once Washington opens fire Yamato is in deep trouble. At that range her armor isn't standing up to 16" super-heavies, as alluded to upthread. 18-20 hits won't sink her like they did Kirishima, but they'll leave her slowed and in a bad state and hideously vulnerable to air attack. And that's assuming Washington doesn't have the time to get more hits in.
So, most likely this leads to Yamato and South Dakota limping away a shambles apiece, which given the state of air cover for both navies is a lot worse a proposition for Yamato than South Dakota.
