Prince of Wales´ hit @ section XIV below main belt

[Karl Heidenreich]

At Denmarck Straits the Prince of Wales was given the credit of having hit the Bismarck in three ocassions. We know that the last hit only damaged a boat and that the second was the responsible of the biggest damage the Bismarck´s got at the battle. But I´m interested in the first hit that pierced the hull below the waterline (and below the 320 mm main belt) into Section XIV.
Being a 14" projectile of the PoW it achieve going thru the hull and was only stopped by the torpedo bulkhead. The damage, not fatal, not even crucial afterwards, tells us that there was, probably, a problem with the Bismarck´s armour design.
Wasn´t the main belt armour too shallow as it gives proof the PoW´s hit?
What would have happened if the hit wasn´t a 14" of the PoW but a 15" from the Hood?
Moreover, the second hit, the real important one, above the waterline at the bow in Section XXI pierced the hull on it´s way in and out, isn´t it?
Being the amour of the Bismarck one of her main strenghts, with a 70% of her lenght protected and with a ratio of PC/TC of 17/22 wasn´t too easy for the PoW to hurt the Bismarck?
Another thing, in her last battle, is it there evidence that Bismarck received equivalent damaged from 14" shells of KGV and/or 16" of Rodney?

[Bgile]

I don't think there is a lot to choose between a hit from PoW or Hood, unless it's on a turret face or barbette at a range where 15" will penetrate and 14" won't.

Remember that the hit on the lifeboat wasn't inconsequential either. It damaged Bismarck's catapault so they couldn't launch the Arado.

Didn't the underwater hit result in the eventual loss of a boiler room? IIRC the holding bulkhead failed to prevent damage and flooding to the compartments behind it. That would have limited max speed if it wasn't already limited by the bow damage.

PoW's belt was a bit deeper than Bismarck's and she also suffered a hit below it. The internal system used on Yamato and the newer US battleships probably would have stopped it, but there are tradeoffs there also. Every design has it's compromises.

[Hartmann10]

I really think that the yamato was well armoured versus those underwater impacts, but, I have a doubt: If the armour of USA battleships tappered down until only some 1 to 2 inches, wouldn´t it had suffered a similar damage that of the Bismarck? Thanks in advance for the answers

[Karl Heidenreich]

Some questions:
The armour scheme of the Yamato was pretty similar to the Iowa Class, isn´t it? I mean, both vessel´s armour were design around the citadel at the "center" of the ship leaving bow and aft disprotected? The Bismarck and the British capital ships were designed with another philosophy: having the hull lenght protected.

[Bgile]

I really think that the yamato was well armoured versus those underwater impacts, but, I have a doubt: If the armour of USA battleships tappered down until only some 1 to 2 inches, wouldn´t it had suffered a similar damage that of the Bismarck? Thanks in advance for the answers

Yes, they were much thinner near the bottom, the idea being that the shell would have much further to travel near the bottom of the system and also much further within the ship because of the angle of the belt. Keep in mind that these ships also had a holding bulkhead similar to Bismarcks BEHIND the internal armor belt. In the case of the US that was made of STS and was I think about 1.5" thick.

[Bgile]

Some questions:
The armour scheme of the Yamato was pretty similar to the Iowa Class, isn´t it? I mean, both vessel´s armour were design around the citadel at the "center" of the ship leaving bow and aft disprotected? The Bismarck and the British capital ships were designed with another philosophy: having the hull lenght protected.

Yes, that is true. Both designs have their advantages. Remember Bismarck's didn't prevent a hit from PoW from causing major damage to the Bow. The more inclusive system was better against small caliber hits from destroyers and against fragmentation from near misses by bombs, but IMO was really irrelevant to hits from battleship size guns.

Also, S. Dakota received many close range hits from 5" to 14", and the unprotected ends of the citadel didn't prove to be a problem for her - there was very little flooding. I think that in practice there just weren't that many waterline hits and the flooding that did occur was quickly corrected with ballast shifting and a small amount of counterflooding. It's very hard to sick a battleship with gunfire - Bismarck is a good example of that.

[Karl Heidenreich]

Bgile wrote:

Also, S. Dakota received many close range hits from 5" to 14", and the unprotected ends of the citadel didn't prove to be a problem for her - there was very little flooding.

So, being this the case then, when attacking a Battleship of the Yamato or Iowa Class, it´s better not to load and fire AP shells but, instead, HE ones. These shells, having the chance of hitting the bow and/or aft portions of the vessel, will produce fires and create havoc among the crew.

[marcelo_malara]

The discussion of if it´s better to fire AP or HE shells against a battleship was a long standing one. The proponents of HE used your own words: destroy the unprotected parts of the ship, which were larger than the protected ones.
In the end both Germans and British developed a semi armour piercing shell (named SAP in Germany and CPC in Britain), which provided a limited amount of armour piercing coupled with a larger bursting charge than an AP one.
In the end I believe that the AP proponents won the day.

[Bgile]

I tend to agree that AP is the better choice. At least with AP you can destroy secondary batteries, whereas most of them were protected against fragmentation damage.

An example of the effect of HE is the CA USS San Francisco at the first battle of Guadalcanal. She was hit by about 50 shells from 5" to 14" in caliber, but they were all HE, because the Japanese force was on a mission to shell the US airfield on Guadalcanal. Her main armament remained in action and although she suffered many casualties and lost all communications equipment and almost all of her open 5" guns were put out of action, she remained in the fight and lived to fight another day. All fires were extinguished within a short time after the battle. If she had been hit by AP shells she would have been in much worse condition.

When Kirishima was taken under fire by Washington, she was hit by about 40 5" common shells which did a lot of damage to her superstructure and started fires, a 16" AP shell wrecked her steering gear, which was behind armor, and that ultimately resulted in the loss of the ship.

[Matthias]

Anyway, I guess PoW hit on Bismarck's bow is overstimated.
I mean, we know the ship could anyway perform her maximum speed during the Denmarck Strait battle, after had received the hit.
It is true that speed, later, had to be limited anyway because of the fuel comsumption, but I don't think the british shell performed any structural damage which impeded Bismarck to reach her full speed, if Lütjens needed it, once the water ways were repaired..

[Tiornu]

A single hit below the waterline is not necessarily indicative of a flaw or a design error; here we have a case of design compromise. It would be nice if the entire hull could have 20 inches of armor, but that's not possible.
In comparison with other modern battleships, Bismarck's belt was a bit on the narrow side--15.8 feet--but not outrageously so. Remember, in the same battle, PoW took a hit below her belt, and the KGV design had an extensive belt. (23 feet--perhaps it would be better to measure the UNarmored hull below the waterline)
Yamato, SoDak, and Iowa had belts that continued down to a joint atop the ship's bottom. (Heck, Yamato's armor went all the way around the bottom and up the ither side.) NC had a relatively narrow belt (14.5 feet) but with partial coverage from an internal belt that also went to the ship's bottom. But such things were exceptional in the battleship world. Littorio's belt was narrow (12.3 feet). Richelieu had good coverage (18.8 feet). If SoSo had been completed, she would have had good coverage (20.5 feet), though for some reason less than 6 feet were submerged. (Mr Cynic says the ship would have turned out terribly overweight anyway....)
The differences between Bismarck and Iowa mean that Iowa would suffer more from HE than Bismarck. It doesn't mean that Iowa would suffer more from HE than from AP.
The 14in shells that hit San Francisco were not HE. If they had been, she probably would have been sunk. Instead, the shells were hollow casings filled with little incendiary tubes and shrapnel. (I refuse to restrict "shrapnel" to its original, limited definition.)
I dispute the commonly cited (and official) figure of 40+ 5in hits on Kirishima. This would require a hit rate of 40% or so, which seems unlikely--not even the 16in guns claimed such a high hit rate. Kirishima was indeed lost to the effects of 16in AP. She was crushed, flooding uncontrollably.

[Bgile]

Hi Tiornu,

Interesting points, and I agree with some of what you say, but...

You seem to be implying that only AP can seriously damage a battleship. If true, how do you explain the loss of Hei? Was she disabled only by 8” and 6” AP penetrating her armor? Wouldn’t fires started by 5” and AAA at ranges less than 1000 yds have something to do with it?

I assumed a 10 min firing period and estimated the number of shells possible for USS Washington to fire at Kirishima. It came out as 10 * 2 * 9 = 180 16” shells and 10 * 15 * 10 = 1500 5” shells. That’s 5% hits for 16” and 2.6% hits for 5”, assuming 9 and 40 hits respectively. I know this isn’t even close to precise, but it should be valid for comparison, the point being that the 5” had about half the hit percentage of the 16”.

Remember, the Japanese damage control organization didn’t always seem to deal with fire adequately.

[Tiornu]

Hey, Bgile.
No, I'm not implying that only AP can seriously damage a battleship. I'm saying that AP is the better choice.
Yes, the critical damage to Hiei was caused by 8in AP shells. This was what rendered her incapable of retiring. Oddly, the 8in hits that crippled her rudder may have been duds. In any event, flooding took out her steering. She also had some damage in her vitals, in her machinery spaces, and this aggravated her difficulties in trying to get beyond the reach of Henderson Field's aircraft. The topside damage caused by 5in and other shells certainly caused problems and interfered with her ability to inflict more damage on the Americans. Regarding the ship's survivability, it may be that the most important result of this topside damage was its impact on shipboard communications and command. That is entirely a guess on my part. The smallest projectiles of all, machine gun fire, killed command personnel on the bridge.
Somewhere around here, I have exact figures for shells expended by Washington against Kirishima. Here we go: 75 rounds of 16in, 107 rounds of 5in. Details on the hits suffered by Kirishima are elusive. Ugaki reported that she took "more than six" 16in hits. I've seen a hit diagram from a ship's officer indicating thirty-seven total hits, but the caliber is not specified. Perhaps relevant to the original topic, six of the hits (which would have to have been 16-inchers) struck below the waterline. The Kongo design introduced an interesting feature which appeared also in HMS Tiger and in later IJN ships: a flange of 3in armor appended below the main belt, specifically intended to counter submarining shells. I think most of us are aware that Japan designed the Type 91 AP shell to maximize its underwater performance, and that the optimal range for such performance was out near 20,000 yards (close to Denmark Strait ranges). However, this 3in flange derived from experience in the Russo-Japanese War where the hits came at much shorter ranges. So the six underwater hits from Washington may not be much of a surprise. One thing we do know about Kirishima is that three of her four main turrets were knocked out in about seven minutes of gunfire. This comprehensive degrading of her ability to fight back would have been impossible with HE ammo.

[marcelo_malara]

If true, how do you explain the loss of Hei? Was she disabled only by 8” and 6” AP penetrating her armor?

Hiei´s belt was just 8", almost a cruiser armour. And the battle was fought at point-blank range (I believe 2000 yards).

[Tiornu]

A genuine 8in AP shell (the US introduced such ammo in the late-1930's) would be able to penetrate an 8in belt. Outboard of the belt, Hiei had a bulge compartment containing buoyancy tubes. The effects of this on an 8in shell, I don't dare theorize. Inboard of the belt was the protective slope which, for the most part consisted of 3in HT steel, perhaps in a three-layer lamination. I suspect it would take an intact 8in shell to get through there. After that, there would be some HT bulkheads that would serve well against splinters. I wonder if Hiei's machinery woes came from a submerged hit.
The steering hit would be much easier. Back in the good old days (c1914), the Americans were the only ones giving thick protection to the steering compartment. Hiei had a 3in belt there, which was not especially poor even by battleship standards of that time. Behind it was a 2in slope.