RFC equipped Yamato vs. Iowa

[Tiornu]

The burster in a 250kg bomb will probably be 4-6 times as large as that in a 16in shell. Nevada was operating with an incomplete and unprepared crew, which explains why magazines were flooded even when not in danger.
Yamato's secondary barbettes had 25mm D steel laminated to 50mm CNC. I think there was a thick coaming around the opening in the armor deck, perhaps 200mm in thickness.

[Bgile]

The logical conclusion is that even Yamato's fighting ability would be degraded by multiple 16" hits even if they were non penetrating.

Hi lwd, I would like to know what impacts (aside from the bridge and fire control positions) do you believe would affect Yamato´s ability.

Anyone can tell the armour of the secondary turret´s barbettes?

I would suggest reading the damage report for USS South Dakota to give some idea of the kind of havoc a large number of non-penetrating hits can cause. Other than general havoc, fires started, and the command personnel felt blind because they had relied on the radars which were largely put out of action.

I have the impression that you think a ship can have it's superstructure essentially wrecked and continue operations normally. That isn't generally the feeling among navies of the world, and S. Dakota I believe spent a number of months being repaired, and wasn't available to the Pacific fleet while that was going on.

[RNfanDan]

Other than general havoc, fires started, and the command personnel felt blind because they had relied on the radars which were largely put out of action.

It's just this sort of thing--that command personnel felt blind while lacking radar--that seems to lend itself to my (admittedly, jaundiced) view that USN personnel not only incorporated radar fire control and automation into their tactics, but indeed placed too much reliance upon it. By implication, such an account could be supportive of a claim that if one can defeat USN radar, one can defeat USN ship with said radar, even if the attackers lacked radar of their own.

Had such reliance shifted dangerously toward complete dependency, even to the point that, by 1942, the USN had eschewed traditional gunnery and surface combat fundamentals....like optics and verbal communications? Where was redundancy (in operational terms, not in the electronics)? Was a modern USN battleship any longer capable of performing without radar, in the style of Bismarck vs. Hood, less than two years earlier?

Or, was the situation South Dakota found herself in, simply never that dire in the first place?

[Tiornu]

SoDak's situation is hard to assess because the DR completely ignores the sabotage to the electrical system.
WWI has several examples of ships suffering multiple no-penetrating hits. How many large-caliber hits did Tiger take at Jutland?

[marcelo_malara]

I would suggest reading the damage report for USS South Dakota to give some idea of the kind of havoc a large number of non-penetrating hits can cause.

I would take the 30.000 yards probability (which would be higher than the 40.000-35.000 range being analized). That means that of the 108 shells fired, 1.51 shells would impact. So for those first 5000 yards Iowa had 1.5 shell to stop her. A and B turrets magazines would not be penetrated because of the aditional protection, and the machinery spaces was behind the superstructure as seen from the shell, so they wouldn´t be reached either.

The 35.0000-25.000 yards leg would be travelled by Yamato in 12 minutes. That would be 24 broadsides for Iowa, 216 shells. Using the same hit probability (be fair, I used it for 10.000 yards of less probability, so let me use it for 5.000 yards of higher) would make her hit Yamato three times

We are talking of 4.5 shell here, not a large number. Then Yamato would start firing and Iowa would be punished.....and this would be penetrating shells.

[lwd]

...
Hi lwd, I would like to know what impacts (aside from the bridge and fire control positions) do you believe would affect Yamato´s ability.
...

Well fires can cause all sorts of problems and fighting them during a battle is even more problematic. Especially given Japanese fire control doctrine. If you are looking at other potential sources of problems due to hits that don't penetrate the main armor there are of course ones that let water in. Others could damage the main armament. There's also the fact that hits can degrade armor even if they don't penetrate. There are also more chances of penetration than you might think as most calculations ignore edge effect for instance.

[lwd]

...
We are talking of 4.5 shell here, not a large number. Then Yamato would start firing and Iowa would be punished.....and this would be penetrating shells.

??? How did you come up with that number? There is no reason Iowa needs to let Yamato fire at her at all. Certainly not until she's on fire and showing signs of distress.

[Tiornu]

There is no reason Iowa needs to let Yamato fire at her at all.

Yamato does not need Iowa's permission to open fire.

[Bgile]

We are talking of 4.5 shell here, not a large number. Then Yamato would start firing and Iowa would be punished.....and this would be penetrating shells.

Marcelo, you are making an assumption that the poster you quoted was correct. I believe there would be more hits than that. Also, Iowa is capable of penetrating Yamato's deck armor above about 34,000 yds, so there could well be one or more hits which effected her in a significant way. Even 4.5 penetrating deck hits can be devastating, and there is certainly a chance of slowing her. Also, if I read Facehard correctly below about 30,000 yds Yamato can't penetrate Iowa's deck armor, so until the range closes to something likely to generate belt hits, Iowa is still not likely to have her vitals penetrated.

[marcelo_malara]

Hi Bgile:

I took the hit probablilty from navweaps.com. I used two legs, one for the 35.000-40.000 yard interval (in which the deck CAN be penetrated) and the other for the 35.000-25.000 yards interval (in which the deck CAN NOT be penetrated). For the first leg the probability for Iowa, firing continuosly, of hitting a Bismarck size target is 1.5 times. So I figure that all the money goes in that hit, because at less range the vitals would not be penetrated and below 25.000 yards Yamato will open fire, so Iowa can be damaged too. The "inmunity" of Iowa is for Yamato to stay outside the 35.000 yards circle, assuming that Yamato would not hit at that distance (which is also an asumption).

[Tiornu]

With a little bit of luck, Iowa can penetrate Yamato's deck armor from as close as 30,000 yards by firing at the usual 45cal muzzle velocity, a technique for which the FC system was equipped.
Unlike Iowa, Yamato can penetrate her target's belt at almost any range inside 30,000 yards

[lwd]

There is no reason Iowa needs to let Yamato fire at her at all.

Yamato does not need Iowa's permission to open fire.

But if Iowa's captain has a historical knowledge, which is what we are talking about, there is no reason he can't keep the range well over 30,000 yards where Yamato doesn't have much chance of hitting anything. Indeed Marcelo suggested that Yamato's optimum strategy was to close as rapidly as possible and not even try to fire at over that range.

Marcelo again there is no reason (lacking a very contrived one) that Iowa cannot maneuver to keep Yamato over 30,000 yards and indeed around 35,000 yards. As I pointed out earlier if Iowa persues a course 30 degrees away from Yamato it cuts the latters closing rate in half. If Yamato gets too close then Iowa can turn away and open the range. If she has been making smoke or it is night Yamato may even loose track of where she is.

[RNfanDan]

There is no reason Iowa needs to let Yamato fire at her at all.

Yamato does not need Iowa's permission to open fire.

But if Iowa's captain has a historical knowledge...

What historical knowledge? Until the ships made an appearance before USN pilots and/or at Leyte against the jeep carriers, the USN had little more than educated guesses about Yamato and Musashi, in terms of their immense armament, size, speed, etc. Even the softshoe brass of the USN were unaware just what these ships' specifications were, in detail. Most of it was a mystery or limited at best, at least until at or near war's end.

The best knowledge a USN commander could have brought to a first-encounter battle against these behemoths, is that of his own ship's offensive capabilities. He would very likely have known little to nothing about his opponents' IZs, the fact that his own ship's IZ didn't exist against them at most ranges, and probably not a great deal about their top speed (though this would reveal itself within short order). Talk about a contrived circumstance....1944-45 USN is very different from Desert Storm's pre-planned scenario against a known quantity, and intimate knowledge of the opponent's cards in hand before the betting begins. The realities of the 1944-45 Pacific war were far from providing the "historical knowledge" necessary to support a hypothetical, prefabricated tactical plan for a "perfect" surface action against these giants.

[Bgile]

With a little bit of luck, Iowa can penetrate Yamato's deck armor from as close as 30,000 yards by firing at the usual 45cal muzzle velocity, a technique for which the FC system was equipped.
Unlike Iowa, Yamato can penetrate her target's belt at almost any range inside 30,000 yards

Isn't there an angle at which an AP shell won't "bite" and tends to richochet off? I'm wondering whether there is a range at which Yamato's shells would do that against the 19 deg belt armor of Iowa. Maybe it's so long as to be out of this picture, but I haven't found the info yet.

[Brad Fischer]

Wow, I’m surprised that this thread is still active. I think I’ll pass on the main topic of discussion but I’d like to comment on the hit probability model from Navweaps.com that Mr. Malara commented on above. That probability model comes from the Princeton University Statistical Research Group (SRG) which submitted its findings to the Applied Mathematic Panel of the National Defense Research Committee (They submitted similar reports on CA and CL accuracy as well.) The problem with that model isn’t the protocol but rather data pool.

Those who are readers of Warship International may recall that Bill Jurens and I wrote a two part article on the USN’s “fast battleship” gunnery during WWII. The hit probability model that we used was a derivative of the SRG model that was revised using current research. The original SRG report had a small data pool from battleships with the new fire control – that is the Mark 38 GFCS with the Mark 8 radar – and as a result was forced to use data from interwar gunnery exercise to supplement their data. The report was researched in early 1943 and had only 15 exercises for a total 145 salvos from which to draw from with the new equipment. By contrast, our data pool was much more extensive having 50 exercises of AP service velocity alone with a total of 401 salvos.

The result is that our model better matched the actual hit percentages that were actually observed in exercises with the new fire control equipment. Interestingly, the SRG model which also draws from prewar exercises, matches up better with the prewar hit percentages. This isn’t a knock on the SRG or the report at all; they just didn’t have the data pool to draw from. We had the advantage in being able to look at the entire war as opposed to just 18 months or so. Below is a tabulation of hit probability based on the USN’s battleship constructive target (90° target angle).

40,000 – 8.7% (Extrapolation)
35,000 – 10.5%
30,000 – 12.8%
25,000 – 15.9%
20,000 – 20.2%
15,000 – 26.9%
10,000 – 39.8%
5,000 – 73.2%

Brad Fischer