Iowa vs Vanguard

[eocoolj]

Since these types of threads always seem to be popular, what would be the outcome if an Iowa and the HMS Vanguard for some reason crossed swords, one on one? The Vanguard has fewer guns of smaller caliber than the Iowa, but I assume her fire control would be approximately equal? The Iowa's have occasionally been criticized for not being as well armed as they could have been, so maybe a few (or more than a few) well placed 15" rounds would be effective against her?

Maybe it would come down to which ship could take more punishment and keep on fighting? Thoughts?

[Doomarias]

Id factor in Iowas greater speed aswell

[smilingassassin]

Id factor in Iowas greater speed aswell

It would depend on the seastate, the speed advantage might be negated somewhat.

[ace16807]

Wait, are we assuming that the Vanguard vs. Iowa at the same time period? I'm assuming that's the case, otherwise it wouldn't be fair at all.

Anyhow. The Iowa was designed to be a "fast battleship", so it's no surprise that it has a bit less armor/armament than expected, but eh. I can't say with any definitiveness. I'll leave this to the experts here.

[eocoolj]

Wait, are we assuming that the Vanguard vs. Iowa at the same time period? I'm assuming that's the case, otherwise it wouldn't be fair at all.

Yes, definitely. Both in late 40s/early 50s configuration.

[Tiornu]

For me, the salient difference is Iowa's massive firepower advantage: a 24,300-lb broadside versus a 15,504-lb broadside. Compounding this, Iowa has much better protection for her main battery. Vanguard's advantage in protection is her excellent percentage of armored volume.
Iowa had good seakeeping. Vanguard was, by reputation, the best seaboat of her age. The USN did not consider speed to be any significant tactical factor, except for the ship attempting to escape.
I don't know any basis for gauging the radar-ECM match-up.

[Nathan45]

Using the post war USN 16in Shell (Mk 8 6-8 (1945-92) 2700-lb shell with 2352.5-lb body weight) with facehard 5.8, the vertical 12.75 CA armor belt of Vanguard amidships (Backed by a .875in D steel backing plate and a assumed 2in of cement.) is fully vulnerable out to 33000 yards. Part of the projectile will penetrate the belt out to 38000 yards. This is with a new liner at a 0 degree target angle. At 20 degrees, the machinery belt is still fully vulnerable out to 30000 yards, and partly vulnerable to 35000 yards. Her Barbettes (12.75in CA, no backing, curved) are vulnerable to a perfect hit (dead center line, unlikely) out to, well, anywhere, (38,000 yards, fully vulnerable at 34,000). A more likely median hit (halfway between the outer edge of the Barbette and the center, a 30 degree tangent angle.) is vulnerable to about 33,000 yards for a hit that only partially penetrates (still likely to jam the turret). A hit at 28000 yards will likely penetrate and detonate in full order.

Her magazine belt armor is about 1 in thicker and inclined somewhat, so how effective it is would depend on where its hit, but you can figure its vulnerable to varying degrees at a 20 degree target angle out to about 24,000 yards at least.

Deck armor is tricky, since USN shells penetrate better then expected with current formulas. USS Massachusetts put a shell into Jean Bart's secondary magazines at 25000 yards, which had comparable protection to Vanguards magazines. the 16/50 of Iowa didn’t have quite the same deck penetration, but it was close.

Iowa's protection is more complex. Her splinter belt will decap the RN 15in shell if hit at obliquities higher then 15 degrees. However a shell can penetrate the deck above the splinter belt and avoid the splinter belt entirely. With Cardonald shells, (latest shell available with facehard.) I've calculated the following vulnerabilities.

At a 0 degree target angle, belt is completely safe beyond 19,000 yards if it hits the splinter belt, its vulnerable to varying degrees from 25,000-26,000 yards if it avoids the splinter belt. At 20 degrees the belt will generally never be fully vulnerable if the shell hits the splinter belt (decaped shells usually shatter and are ineffective after being decaped.) but will be somewhat vulnerable to being holed etc out to 14000 yards. If the shell avoids the splinter belt, its fully vulnerable to 20000 yards, and somewhat vulnerable to 22000 yards.

Iowa’s decks should be safe till past 30000 yards.

Iowa’s faceplate should be safe past 12000 yards.

Iowa’s 17.3in barbettes will be partially vulnerable to 25000 yards and fully vulnerable to 21000 yards for a perfect hit. For a more likely median hit with a 30 degree tangent angle the barbettes are partially vulnerable out to 11000 yards and fully vulnerable at 8000 yards.

[Nathan45]

Actually, having doubled checked my numbers, the limit for a 0 degree target angle hit on Iowa that avoids the splinter belt is about 21000 yards, not 26000. At 20 degrees its about 17000.

[maximusslade]

Nathan... are you THE Natan? Nathan Okun

[Nathan45]

Nope, no relation, although I was using his FACEHARD and M79APCLC programs to calculate those numbers. (I may someday need to change my username...)

[maximusslade]

Hmm you might, spitting out data like that and having Nathan as your name...could lead to some confusion.

PS. So all that technical mumbojumbo says that the Iowa has the advantage??

[Nathan45]

Well, Vanguard does indeed have much greater armored volume. She has more armored freeboard, and was generally regarded as the better sea boat, although neither ship was bad in that regard. In addition there may have been post war 15in shells for Vanguard that are not included in FACEHARD that might make up a bit of the difference between the two. (The 1945+ shell I used for the Iowa’s numbers above is significantly better then the older 1944 shell, so such improvement is possible.)

Having said all that, the bottom line is that Vanguards armor is really over-matched by the 16in/50 gun of the Iowa, penetrating Vanguards belt, barbettes and turret face past 30000 yards, and her decks are likely vulnerable past 26000 yards or so. (That’s a double vulnerability zone, the opposite of a immune zone). Iowa’s armor on the other hand, while not ideal (It’s a internal belt, allowing local flooding and leakage from non-penetrating hits and near misses.) does provide pretty good protection at reasonable target angles and reasonable ranges (say 20 degrees and past 18000 yards or so.) from the 15in guns of Vanguard. Vanguard can win, but she would need superior crew performance (or luck) to do it.

[Tiornu]

Vanguard's armor shows the dramatic "buyer's remorse" the RN experienced after the Nelson class. The bow armor is remarkably thick. The forward belt has a maximum 13in thickness with a 5in deck at its top edge. The armored waterline is almost as long as Bismarck's. However, this end armor is very low, and any appreciable flooding could submerge it. This has always struck me as an odd feature. The stern has a similar system, but strangely the steering gear protection is actually substandard.

[zraver]

How good do the fire controls stack up? After all how much armor you might penetrate equires a hit first, and probalby multiple hits.

[Tiornu]

The FC systems were quite comparable. In fact, Vanguard's FC included some American components. Iowa had Remote Power Control for main gun elevation as well as main gun training, and this might be a slight advantage unless the sea conditions made Vanguard's greater steadiness a compensating factor. Vanguard needed a specialized spotting radar which, from memory, was merely a qualified success. But again, I am hesitant to discuss radar since each side would be trying to jam the other. The American system was proven capable of maintaining a fix during radical maneuvers; I don't know if Vanguard could match it.
Both ships were capable of very accurate fire. I suspect the US might have had a slight advantage, so slight that the difference could easily be swallowed up by crew and chance factors.