1

One of Dunnigan's books (I think it was "Dirty Little Secrets of WWII") has exactly this analysis, considering a hypothetical battle between four Iowas and four Yamatos. He comes to the same conclusion: the Yamatos get creamed.

Even at range the Iowas have the advantage, because they can fire twice as fast, and because they had radar targeting. The Yamato's armor belt turns out to be less impressive than it should be, because it was made with inferior steel and mounted badly. The Iowa's armor belt wasn't as thick but it was better made.

The biggest differences were speed (Iowa was 4 knots faster according to Dunnigan), gunnery (Iowa could fire twice as fast) and targeting (the Iowa had radar) and though there's always luck in battle, the Iowas had a significant edge.

It almost happened! Iowa and Yamato were both involved in the Leyte Gulf operation, and except for Halsey chasing a decoy, they might have met!

2 Did the Yamato ever fire its main guns in combat?

3 For that matter, did Musashi ever fire its main guns in combat?

4 Yes, but not the way you mean.  During Leyte Gulf, she fired sanshikidan (incendiary shotgun rounds for AAA use, in effect) rounds from her main armament; this resulted in an explosion of the middle gun of "A" turret.

She never did fire her guns in anger at a surface target.

5 Sorry, I didn't see the Yamato part of the question. 

The Yamato certainly did fire her main guns in combat!  She was part of Kurita's Center Force during the Battle Off Samar, the group that stumbled into Taffy-3.  Yamato put 18" holes into the Gambier Bay and put at least one and possibly more 18" rounds into the Hoel.

6

The ironic thing was the armor mounted on the IOWA-class was not all that good according to the standards of the day.  Class 'A' and 'B' armor plate used by the US Navy were inferior to some of their foreign counterparts (Though contrary to what some people believe, not the Japanese.), which the US Navy apparently did not realize until just before WW2, by which time it was too late.  The need for production during the war precluded the introduction of much better armor. It still does not justify the rubbishing of the IOWAs by certain folks at Avalanche Press and the late David Brown, to mention a few.

Not that the Japanese were any better.  The standard armor used for the Yamato-class was a slightly improved version of the Vickers armor the Japanese obtained during WWI.  The Japanese made it easier to make the armor from domestic resources (Something which some nations - most notably Germany, fail to do so.), but the level of protection was only marginally improved.  They DID develop significantly better armor, but none of it saw production or service.

7 I seem to recall hearing that either way, the armor of an Iowa-class battleship would shrug off a modern anti-ship missile like a spitball.

8 An Iowa would probably shrug off an anti-ship missile if it hit the side armor.  Problem is, ASMs also had a "pop-up" attack pattern, in that it'd come in low, then zoom climb just before hitting the target. It would then dive into the target from above... and the Iowa's deck armor is substantially thinner than its side.

Would they sink her?  No, probably not, but trashing her topsides is just as effective.  "Mission kill" as opposed to "kill kill."  Repairing an Iowa these days would a nightmare, come to think of it...

9 It's a lost technology, like building a Saturn V.

10 A kamikaze actually models the effect and impact of a modern ASM quite well.  The armor belt would shrug off the impact of the attack, but the mission critical parts of the ship that could not be protected by armor could not do the same.

11 With regard to the South Dakota, I long ago read a study that concluded that "Battleship X" would have a very good chance of taking either of the 'Peace Goddesses' if she could maintain the range. It turns out that the shorter 16 inch guns she shipped had much better deck penetration than the 50 caliber rifles on the Iowa, despite firing the same shells. The question would be whether her captain would stay at a range where her plunging fire would be effective or (not knowing anything about Yamato's deck armor) try to close the range...in which case the odds would grow long indeed.

12

I have to see that study myself and while the standard AP round for the SoDaks were 2200 lb sluggers, the IOWAs' standard AP round was the heavyweight 2700 lb.  Both classes could and did fire the differently sized AP rounds from what they were designed for, but they used different standard AP rounds.

C.T.

13 One of Dunnigan's books (I think it was "Dirty Little Secrets of WWII") has exactly this analysis...

As it turns out, it's "Victory at Sea" by Dunnigan and Nofi.  I started re-reading it last night and stumbled across the article.

14 War is boring had an analysis here.

15 All he did is rewrite the source article... this doesn't impress.

16 This is why the Yamato really needed that wave motion gun. (And that redemptive rebuild and motive for fighting, and the much better fighters, and the wave motion warp drive, and....)

17 I'd say it would depend on who got in the first vital hit or series of hits.  If Iowa could blind Yamato by taking out her main fire control director early on (like what happened to Bismarck in her final battle) or score a lucky rudder hit, then she would be meat on the table for the Iowa and her superior speed, maneuverbility, and fire control.  But the Yamato could very easily score crippling hits on Iowa's engines or boilers via short rounds that penetrate under the waterline and thus negate her speed/maneuver advantage.  Nothing's sure in a combat situation.  I sometimes wonder how the Battle of the Denmark Strait would've turned out had Bismarck not scored that freak hit on Hood that blew her magazines. 

18

Dave, when Dunnigan did his analysis, he stipulated that he was considering an action between 4 Yamatos and 4 Iowas, precisely to reduce the luck factor. One ship might get crippled by a lucky hit, but it isn't going to happen four times. The battle would be decided by the fighting characteristics of the ships, which is what he was looking at in his analysis.

And he concluded that the Iowa's would win.

19

 But the Yamato could very easily score crippling hits on Iowa's engines or boilers via short rounds that penetrate under the waterline and thus negate her speed/maneuver advantage.

Given that there is only one confirmed case in the Pacific War where a Type 91 diving round actually worked as the Japanese intended it to, this would truly be a Golden BB shot (All the more so given the tight patterns the Japanese used for their shots.).  We have not even gotten to how fast the IOWA could run on three screws or down one boiler room - unlike many British designs, knocking out one boiler or engine room was highly unlikely to take out another engine room or boiler.

Such hits would decide the battle essentially at once, but you can not really count on them occurring when you need them.

Ob: Brickmuppet's point - I looked up the stats and you are correct that the 16"/45 mounted by the SoDaks had better deck penetration than the 16"/50 mounted by the IOWAs while firing the same 2700 lb AP round.  But the performance was generally small, and the 16"/50 were rated at longer ranges than the 16"/45.