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Armor and protection problems with Iowa class battleships

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I came across a very insightful article about the severe armor and protection problems of the Iowa class battleships by Dr George H Elder. Iowa torpedo protection is very poor design and not properly tested and the navy tried to cover it up.

 

http://www.ghe101library.com/non-fiction-articles/iron-ladies-with-glass-skirts-final

 

Nor is propellant containment the only weak point in the Iowa Class battleship’s design. Their underwater protection system is known to be defective by many naval architects. But very little was said about this important area of concern before, or since, the Iowa Class were reactivated. The US Navy is aware of the scope of these defects, but has done nothing to rectify a situation that could be calamitous should these ships suffer damage from modern torpedoes of mines.

          In the Iowa and South Dakota designs both weight and the advent of Japanese shells with underwater trajectories had to be considered. The designers felt they did not have sufficient weight margins available to employ a heavy multi-layered system against underwater attacks and thick side armor as well. In lieu of making the design changes necessary to employ separate underwater and shell protection system, American naval designers opted to use a common system for both purposes. As Oliver North would say, “It was a neat idea.”

          The side armor of the Iowa class was set several feet inboard, and inclined internally at 19 degrees to the vertical until it reached the top of the ships’ triple bottoms. It was reasoned the side armor would thus form a formidable torpedo protection bulkhead (6.4″ to 1.62″) as well as keep shells with underwater trajectories out. Despite the lack of full scale tests, the system was immediately incorporated in both the South Dakota and Iowa Class. That’s good old Navy foresight for you, although in all fairness to the designers they were pressed for time due to the looming war.     

          In 1939 the Iowa’s under-water protection scheme was finally tested on full scale models in the Philadelphia Navy Yard. The results of the trials were very disappoint­ing. It was discovered that the heavy Class B armor used in the torpedo bulkhead could not bend enough to accept the gas pressures generated by large underwater contact explosions. The system failed due to armor plate cracks and structural failures where the bulkheads joined into the ship’s triple bottom. These defects allowed flooding to take place behind the main torpedo bulkhead, and the system had to modified.

          The modified torpedo protection system was tested in 1943 at the Philadelphia Naval Yard. The results were less than satisfactory and again showed structural defects, but these faults were deemed acceptable. Corrective plans were finally drawn up, but they were too late for the Iowa and her three sisters. Had the Illinois and Kentucky (Iowa Class near sisters) been completed, they would have incorporated the improved torpedo protection scheme. However, their construction was halted and both ships were ultimately scraped.

          Some Navy officials were displeased with the Iowa Class’s underwater protection scheme very early on. In 1944 P. W. Snyder, a Commander in the Bureau of Ships, filed a scathing report on the battleships’ design. He felt the Iowa Class needed six feet more beam and better sub-division to have adequate torpedo protection. But Snyder’s recommendations were rejected by his superiors. It was felt a wider hull would make the ships slightly slower and unable to go through the Panama Canal. Improving the ship’s internal sub-division was too expensive and time-consuming to even consider. So in the end nothing was done.

          Richard Debobes, a staffer for the Senate Armed Services Committee, was unaware of the 1939 and 1943 trials on the Iowa Class’s torpedo protection system. “I can’t comment,” he said. “You must understand that there is an investigation of the turret explosion. These other concerns you have brought up have not even been discussed.” It would appear that the Committee’s staffers are so intent on studying one tree that they are failing to take into account how the forest is faring.

          But Debobes is not alone in his unfamiliarity with the trials on the Iowa Class’s torpedo defense system. No staffer from either the House or Senate Armed Services Committee was aware of these tests. Considering the greatly improved performance of the latest torpedoes, one would hope someone notices there’s a problem here. The underwater pressure forces created by modern torpedos and mines are far greater than those that were used in the Philadelphia tests. Two or three hits by modern underwater explosive devices might be more than sufficient to disable or capsize one of these glass-skirted leviathans.

          What is of more concern is the possible use of underwater weapons with large shaped-charge warheads. If one of these was to hit an Iowa Class battleship there is the distinct possibility hot gases and debris could penetrate one of their magazines–especially the magazine that supplies Turret I (the turret closest to the ship’s bow). The magazine of Turret I is closer to the sides of the ship than the magazines used to supply turrets II and III. The vulnerability of Turret I’s magazine has been a source of concern since these battleships were designed but the Navy accepted the risk given the fine forward hull form needed to achieve the Iowa Class’ high speed.

          Admiral Kinnear admitted that the Iowa Class’s underwater protection was suspect before the ships were reactivated. He said, “We knew that the ships’ underwater protection was a potential weak point, but I don’t recall being briefed on the tests that took place in Philadelphia.” Kinnear went on to say that survivability and armor distribution talks took place in Navy Secretary Lehman’s office, but the precise details of these talks can’t be released for security reasons.

          Navy spokesperson Walker didn’t know about the Philadelphia tests on the Iowa Class’s underwater protection scheme. “I’m not aware of those tests,” he said. “Nothing is in the works to improve the ships’ underwater protection that I’m aware of. I don’t think it’s an area of concern.” After being told about the Philadelphia test results Walker continued to insist the reactivated battleships “can take more torpedo hits than most ships” in the modern Navy. Walker’s view certainly doesn’t say much for the underwater protection of our modern warships.

          Ship Record’s John Reilly also didn’t recall any details about the Philadelphia tests, but said rectifying any shortcomings in the Iowa Class would be difficult. “You’re talking about a total underwater rebuild, and it’s not necessarily worth it,” he said. “The ships are protected by escorts that will keep submarines away.” Reilly explained the Iowa Class has a number of redundant systems that should limit damage from torpedoes. However, he refused to speculate on the effect a shaped-charge torpedo warhead would have on an Iowa Class’s magazines.

          But there are other areas of concern regarding the reactivated battleships besides their dubious underwater protection scheme. Navy spokesperson Walker said the Iowa Class has the thickest armor of any warship afloat. But enormous areas of these battleships are completely unarmored. Of course, these unarmored areas just happen to be where many Navy crewmen serve during battle-stations–another “neat idea.”

          The Iowa Class was designed at a time when the US navy embraced the “all-or-nothing” scheme of armor protection. Heavy armor was restricted to the vital parts of the Iowa Class, and made thick enough to prevent large caliber shells from penetrating it. All other parts of the ships were left unarmored in any meaningful way. The extent of unarmored area was increased in the Iowa Class’s case because their main armor is internal. In short, an armored raft was placed inboard of a relatively unarmored hull and upper deck.  

          The entire waterline of the Iowa Class is protected by mere 1.5″ thick armor plates. The ship’s heavy 12.1″ thick main armored belts are set several feet inside the hull. The deck armor of the Iowa Class is also internal. The main deck is only 1.5″ thick, while two decks down the main armored deck is 6.0″ thick. Most decks above the armored deck are very lightly protected in the Iowa Class, as are the bridge, fire control directors, superstructures, and external communication devices.         The secondary turrets that house the Iowa Class’s 5″ guns only have a maximum of 2.5″ of armor plate. In fact, vast areas above the weather deck have no armor at all. The only structures above the weather deck that are heavily protected are the gun turrets, barbettes, and conning tower. All crew members serving outside these areas are vulnerable to even light shell and missile hits.

          The Iowa Class’s armoring system was put to the test in the WWII naval Battle of Guadacanal where the battleship South Dakota employed an almost identical protective scheme. The South Dakota sustained 26 hits from 5″ to 8″ armor piercing (AP) shells and one 14″ (AP?) hit during her inglorious run in with a Japanese strike force. Despite the fact she suffered no serious flooding, the South Dakota was seriously damaged and had to be dry-docked for repairs.

          The South Dakota’s fire control and interior communications were all knocked out early in the engagement by the shell hits she received in her lightly protected areas. Many of the AP shells that hit the thinly protected superstructure of the South Dakota failed to explode—much as was intended. However, enough damage was done by these relatively light shells to cripple the ship’s fighting abilities. By the end of the Battle of Guadacanal, the South Dakota only had one radar system left intact and was in no condition to mount any kind of offensive action.

Edited by bsbr
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It's a good thing USN never got into a gun duel with IJN or else I Definately think there would have been severe losses on USN side and this ^ just reinforces that theory / estimate.

Just a good thing Pearl Harbor happened or else USN would likely have sailed across the Pacific for a surface battle which the IJN had long been preparing for, including well practiced night attacks involving lots of torpedoes launched from DDs and Cruisers to soften up the USN for the day battles in which the BBs and Heavy Cruisers would engage the USN.

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Just now, Admiral_Thrawn_1 said:

It's a good thing USN never got into a gun duel with IJN or else I Definately think there would have been severe losses on USN side and this ^ just reinforces that theory / estimate.

Just a good thing Pearl Harbor happened or else USN would likely have sailed across the Pacific for a surface battle which the IJN had long been preparing for, including well practiced night attacks involving lots of torpedoes launched from DDs and Cruisers to soften up the USN for the day battles in which the BBs and Heavy Cruisers would engage the USN.

By the time the bulk of the US Pacific fleet was ready to move  the Philippines would have already fallen necessitating a change in strategy.


Carriers are going to prove their worth quickly one way or the other.

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2 minutes ago, Admiral_Thrawn_1 said:

It's a good thing USN never got into a gun duel with IJN or else I Definately think there would have been severe losses on USN side and this ^ just reinforces that theory / estimate.

Just a good thing Pearl Harbor happened or else USN would likely have sailed across the Pacific for a surface battle which the IJN had long been preparing for, including well practiced night attacks involving lots of torpedoes launched from DDs and Cruisers to soften up the USN for the day battles in which the BBs and Heavy Cruisers would engage the USN.

 

Umm there were a number of gun duels between the USN and IJN.

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3 minutes ago, Admiral_Thrawn_1 said:

It's a good thing USN never got into a gun duel with IJN or else I Definately think there would have been severe losses on USN side and this ^ just reinforces that theory / estimate.

Just a good thing Pearl Harbor happened or else USN would likely have sailed across the Pacific for a surface battle which the IJN had long been preparing for, including well practiced night attacks involving lots of torpedoes launched from DDs and Cruisers to soften up the USN for the day battles in which the BBs and Heavy Cruisers would engage the USN.

uhh, USS Washington vs. Kirishima?

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Honestly this article sounds a bit like a hit piece on the ships in response to Reagan's "600 ship navy" and the reactivation/modernization of the Iowas in the 1980s. Most experts would say South Dakota's condition following Guadalcanal proved the suitability of the protection scheme, not that it was flawed.

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7 minutes ago, Lampshade_M1A2 said:

The Yamato class had a similarly flawed TDS scheme, weirdly WG gives it one of the highest ratings in the game.

Due to the arc-welding incorporated in Yamato's "novel" TDS, large torpedoes would be able to punch right through it and explode within the actual ship.

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14 minutes ago, Admiral_Thrawn_1 said:

It's a good thing USN never got into a gun duel with IJN or else I Definately think there would have been severe losses on USN side and this ^ just reinforces that theory / estimate.

Just a good thing Pearl Harbor happened or else USN would likely have sailed across the Pacific for a surface battle which the IJN had long been preparing for, including well practiced night attacks involving lots of torpedoes launched from DDs and Cruisers to soften up the USN for the day battles in which the BBs and Heavy Cruisers would engage the USN.

It's also a good thing the Iowa class battleships never took a torpedo, especially an IJN one with such a massive warhead. A hit from a Long Lance will devastate a Iowa and probably blow it right in half.

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Quote

This article was completed during the spring of 1990

 

Tells you just about everything you really need to know tbh.

 

This is just ANOTHER bsbr clickbait thread, move along folks.

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9 minutes ago, Admiral_Thrawn_1 said:

It's a good thing USN never got into a gun duel with IJN or else I Definately think there would have been severe losses on USN side and this ^ just reinforces that theory / estimate.

Just a good thing Pearl Harbor happened or else USN would likely have sailed across the Pacific for a surface battle which the IJN had long been preparing for, including well practiced night attacks involving lots of torpedoes launched from DDs and Cruisers to soften up the USN for the day battles in which the BBs and Heavy Cruisers would engage the USN.

there were a few gun duels with IJN.

 

kirishima vs uss washington and uss south dakota was a prominent example.

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18 minutes ago, Admiral_Thrawn_1 said:

It's a good thing USN never got into a gun duel with IJN or else I Definately think there would have been severe losses on USN side and this ^ just reinforces that theory / estimate.

Just a good thing Pearl Harbor happened or else USN would likely have sailed across the Pacific for a surface battle which the IJN had long been preparing for, including well practiced night attacks involving lots of torpedoes launched from DDs and Cruisers to soften up the USN for the day battles in which the BBs and Heavy Cruisers would engage the USN.

uhhh what? The article even points to gunnery hits sustained by another USN BB and points out that the ship suffered no critical damage that endangered the ship. Also the article was mostly about torpedo protection not gunnery protection. 

 

As for gunnery battles between the IJN and USN there were many, just not a lot between BBs. 

 

To the OP there are some serious issues with this article like the below:

1 hour ago, bsbr said:

  But there are other areas of concern regarding the reactivated battleships besides their dubious underwater protection scheme. Navy spokesperson Walker said the Iowa Class has the thickest armor of any warship afloat. But enormous areas of these battleships are completely unarmored. Of course, these unarmored areas just happen to be where many Navy crewmen serve during battle-stations–another “neat idea.”

Of course the Iowa had a significant amount of unarmored ship. It was an all or nothing design, just like other BBs of the era including the Yamato. 

 

There are other issues as well but I dont feel like covering them, maybe @DeliciousFart would like to cover it in more detail. 

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Just now, Lampshade_M1A2 said:

By the time the bulk of the US Pacific fleet was ready to move  the Philippines would have already fallen necessitating a change in strategy.


Carriers are going to prove their worth quickly one way or the other.

Yes they would have eventually ( my guess it would probably  have taken handful more years to realize CV Power), but despite growing indications at the time that Aircraft Carriers could kill a Battleship they were often dismissed such as the sinking of an old captured German Dreadnaught since it was not defended by the crew.

So without the major wake up call of Pearl Harbor pretty much ending that debate and only having the Carriers and few smaller ships remaining intact immediately after Pearl Harbor forcing the USN to change strategy the War in the Pacific could have ended up being a Battleship focused war since that was still the major philosophy of most navies at the time and it still was believed to have some power for a little while following Pearl Harbor.

You can hardly blame Naval planners for being skeptical about CVs possibly becoming the main power when BBs were such a powerful force and could be equipped with powerful AA defenses to compliment their other weapons, they carried armor, prior to and very early on in WWII Carrier Aircraft was rather rickety looking often times. So they needed indisputable evidence to prove them wrong about BBs since for example which of these 2 pictures would you rather be fighting in 

A CV like this with planes like those that look like they could be knocked out by of sky with barely any effort....

Or the BB with armor, powerful guns, and good AA. These were what Naval planner would have been looking at lol.

IMG_8956.JPG.57ec826b55a0abf7a0b0b465d063e0ca.JPG

 

IMG_8957.thumb.JPG.6dfe3aa16b08e725be3854e57b45c7be.JPG

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18 minutes ago, Lampshade_M1A2 said:

The Yamato class had a similarly flawed TDS scheme, weirdly WG gives it one of the highest ratings in the game.

Maybe because the Torpedo armor was not entirely flawed if I remember correctly, there was just a weak spot where armor belts met that could be exploited, plus the fact USN dropped dozens of torpedoes onto the water all around the Yamato to keep her dodging so they could focus bulk of the hits on 1 side.

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2 minutes ago, Admiral_Thrawn_1 said:

Yes they would have eventually ( my guess it would probably  have taken handful more years to realize CV Power), but despite growing indications at the time that Aircraft Carriers could kill a Battleship they were often dismissed such as the sinking of an old captured German Dreadnaught since it was not defended by the crew.

So without the major wake up call of Pearl Harbor pretty much ending that debate and only having the Carriers and few smaller ships remaining intact immediately after Pearl Harbor forcing the USN to change strategy the War in the Pacific could have ended up being a Battleship focused war since that was still the major philosophy of most navies at the time and it still was believed to have some power for a little while following Pearl Harbor.

You can hardly blame Naval planners for being skeptical about CVs possibly becoming the main power when BBs were such a powerful force and could be equipped with powerful AA defenses to compliment their other weapons, they carried armor, prior to and very early on in WWII Carrier Aircraft was rather rickety looking often times. So they needed indisputable evidence to prove them wrong about BBs since for example which of these 2 pictures would you rather be fighting in 

A CV like this with planes like those that look like they could be knocked out by of sky with barely any effort....

Or the BB with armor, powerful guns, and good AA. These were what Naval planner would have been looking at lol.

 

The USN would have just learned from other events if Pearl Harbor hadnt happened. Like the sinking of the Repulse and Prince of Wales. 

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The tone of the article sounds more like an editorial than a scholarly publication. Going over the whole article, it appears that the author has some valid consternation against the USN due to their admittedly dismal handling of the investigation into #2 turret explosion on the Iowa in 1989, i.e. quickly blaming one of the sailors on pretty dubious grounds, but then went on a large tangent and diatribe against the Iowa's design without really much technical explanation besides using secondary sources. By the way, a lot of his arguments against the Iowa's SPS are just rehashes from Norman Friedman's book on USN battleships, and conversations I've had with Mr. William Jurens in the past few weeks have been much more insightful on the Iowa's SPS than this article.

 

By the way, bsbr, what is up with your borderline obsessive hatred of the Iowa?

Edited by DeliciousFart
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More information from Dr George H Elder

http://www.ghe101library.com/non-fiction-articles/in-defence-of-clayton-hartwig

The USS Indiana’s February 1, 1944 ramming was in a sensitive spot, and that’s why the ship came so close to sinking. In 1945 a vulnerability study of the South Dakota Class showed that if they were hit heavily in the stern area (between frames 113 and 128) this damage would probably sink ships of this class. In effect, Mr. Ley has pointed out an Achilles’ heal in the all or nothing armoring system that the US Navy employed in the South Dakotas (e.g., insuff­icient reserve of armored buoyancy spaces). Please note that the Iowa Class utilizes an almost identical protection scheme, and may be just as vulnerable to damage to her “soft ends.”

7. In the naval Battle of Guadacanal the USS South Dakota suffered the same type of damage that could drive an Iowa Class battleship away from its mission. Remember, any ship is only as useful as its sensors, and the Iowa Class’s sensors are just as vul­nerable as the South Dakota’s were. Two or three Exocet hits might be enough to send an Iowa Class ship out of a theater of action.

          I wish Mr. Ley had also listed the September 15, 1942 torpedoing of the USS North Carolina, but I can understand why he didn’t. She was the only modern US battleship to be struck by a torpedo during WWII. A single Japanese torpedo hit her forward, and the flash from its explosion reached her forward 16″ magazines. A rapid inrush of water prevented a magazine disaster, but the effect of this torpedo damage and subsequent flooding was far worse than had been expected. This can hardly be unqualified support for the effective­ness of our battleship’s side protection systems. It should be noted, however, that the Iowa Class employs a different, although not necessarily superior, underwater protec­tion scheme than did the North Carolina Class.           

          It is important to understand that details concerning the faults of the Iowa Class’s torpedo and side protection systems are not “sketchy” or hard to find. I had included some simplified diagrams of the Iowa’s side protection and armoring system with my last article to demonstrate my concerns, but these drawings were not printed. I think Mr. Ley would be well advised to study Norman Freidman’s U.S. Battleships in detail. The underwater protection and armoring system employed by the South Dakota and Iowa Class are discussed, as is the scheme the abortive USS Montana Class (the Iowa’s successors) would have employed. The Montanas would have discarded the Iowa’s suspect passive defense scheme altogether in favor of a more effective layout. It’s a shame that they were never built.

          Mr. Ley’s article contends that the Iowa Class has a sound underwater protection scheme, but the facts he presents do not back his contentions. The two Philadelphia tests of the Iowa’s torpedo protec­tion scheme, the ramming damage suffered by the USS Indiana, and the 1945 study of the South Dakota’s torpedo defense system are conclusive. The Iowa Class’s underwater protection scheme did not come up to design expecta­tions even against WWII weapons, which is why the scheme was going to be discarded in the Montana Class. Modern torpedo’s and mines are far more effective than their WWII counterparts, so there’s no doubt that these ship’s underwater protection systems still remain gravely suspect.

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13 minutes ago, Admiral_Thrawn_1 said:

Maybe because the Torpedo armor was not entirely flawed if I remember correctly, there was just a weak spot where armor belts met that could be exploited, plus the fact USN dropped dozens of torpedoes onto the water all around the Yamato to keep her dodging so they could focus bulk of the hits on 1 side.

You know both the Yamato and Musashi both got hit by individual submarine torps on separate occasions right? And both times the TDS failed to protect the ships, the Yamato even suffered a main battery magazine flooding. Seems like it was flawed enough. 

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Although they're conceptually similar and share many design characteristics, the Iowa's torpedo SPS is not the same as the SoDak. The joint between holding bulkhead 3 (which has the Class B lower belt) is substantially reinforced at 1.6" compared to SoDak's 1". The Iowa's SPS is also slightly more volumetric, and the longitudinal spacing of the traverse bulkheads is also denser. I'll quote myself from my own thread.

 

On 9/26/2017 at 10:58 PM, DeliciousFart said:

I shall resurrect this topic to briefly discuss SoDak and Iowa TDS, as I had some interesting and informative conversations with naval historian Mr. William Jurens, as well as some useful information from recent Warship International publications (Volume 53, Issue 4, page 289-294). I'll try to summarize the information below.

 

As with the Yamato class, the SoDak extends the lower belt all the way to the keel to better protect against underwater shell hits. Treaty tonnage limitations and the need to adequately protect against 16" shell fire meant that the belt was carried internally, and the lower belt formed the fourth torpedo holding bulkhead (there's a total of 5 when counting the shell plating). The tapered edge of the STS armor is welded to the outboard longitudinal bulkhead plate of the triple bottom. Where the Japanese and American systems differ is the way that the lower belt is attached to the upper belt, as well as the location of the joint.

 

On the Yamato system, the upper and lower belt joint (along with their individual backing plates) was well within the torpedo bulge, and formed a discontinuity in one of the holding bulkheads. In contrast, the SoDak's upper and lower belt joint was above the bulge shelf plate, thus making the structure more uniform and the use of welding at the bottom largely avoids a sharp structural discontinuity. As discussed, while Yamato's upper VH belt and lower NVNC belt joint was joined by tap rivets, the SoDak's joint was a keyed joint, were a keyway slot is machined into the edges of the upper and lower belt, and an STS key held the belt plates together, with the entire joint back by the 0.875" STS backing bulkhead that the armor plates are tap riveted to. The SoDak's joint is then far stronger in shear compared to the Yamato's joint. Bending is a more complicated affair, since the SoDak's 0.875" STS backing plate behind the joint would provide the bending strength as the keyed joint between the belt plates wouldn't contribute at all to the resulting tensile load; the Yamato's joint again uses the rivets to resist bending loads, as the backing plates for the upper and lower belts at the joint are separate. Mr. Jurens is of the opinion that a weaker joint for bending is not necessarily a detriment as such a joint is more likely to deform and absorb energy before rupturing, and that if the system does fail, the failure is at least more predictable. Personally, I think the problem with the Yamato is that because of the non-continuous backing plate for the upper VH and lower NVNC belts, the riveted joint is weak in *both* shear and bending, which makes it much more liable to being breached, in addition to being shallower at only 5.1 m system depth.


Caisson tests in 1939 however demonstrated some flaws of the SoDak system, as stated by Norman Friedman in his US Battleships book. Several secondary sources specifically point to the lower belt's joint with the triple bottom as being likely to rupture. In any case, this lead to a change in liquid loading of the compartments from void-liquid-liquid-void-shell to void-void-liquid-liquid-shell, as well as a revision in the method that the lower belt is attached to the triple bottom; the revised joint had the STS armor plates welded to the outboard triple bottom bulkhead, with the welded seam reinforced by riveted HTS buttstraps. As a result, the shearing is loaded on the weld and the buttstrap plates, while tensile forces are loaded on the rivets and buttstraps.

 

The Iowa's TDS largely reuses the conceptual design of the SoDak, with the upper and lower belt being keyed together and mounted on 0.875" STS, but has several key differences to strengthen the system because it was laid down in 1940, well after the 1939 caisson tests, and had more opportunity for design improvements. The overall support structure of the armor belt and the hull is heavier, which is a byproduct of being a larger vessel and higher speed. The heavier support structure and STS shell plating allowed belt armor to thin from 310 mm on SoDak to 307 mm on Iowa while providing the same protection levels. The taper of the lower belt is also different, and the lower edge of the belt where it meets the triple bottom is 1.6" thick on Iowa compared to 1" thick on SoDak, and results in a considerably stronger joint at the triple bottom. The Iowa's shell plating is also flared slightly outwards compared to the vertical shell plating of the SoDak, so the final holding bulkhead on the Iowa was placed further inboard to provide the same depth. Other improvements include increase in volume of the Iowa's compartments, as well as denser longitudinal spacing of the traverse bulkheads, which also has the benefit of greater subdivision of the machinery spaces to reduce potential progressive flooding.

 

Unfortunately, the exact details of the SoDak and Iowa TDS, including the exact results of the caisson tests, are still classified, but the information provided by Mr. Jurens indicates that despite initial design flaws, the revised TDS of the SoDak and especially the Iowa are very robust and likely met the design requirements. As an addendum, here is a comparison of Iowa, SoDak and Yamato ship sections (in that order), roughly to scale. You can see that despite Yamato's greater beam, the TDS bulge is actually narrower than on the American ships.

 

New Jersey.PNG

South Dakota.PNG

Yamato.PNG

 

Edited by DeliciousFart

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15 minutes ago, DeliciousFart said:

By the way, bsbr, what is up with your borderline obsessive hatred of the Iowa?

What is up with you fawning over the Iowa and USN BB?

There's so much myth and rah rah about how great the Iowa is and how it's the best BB ever build that no one even cares about its dangerous flaws and pointing them out just gets buried by hatred on this forum. I'll take Dr George Elder over your amatuer analysis attempt any day.

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12 minutes ago, RipNuN2 said:

 

The USN would have just learned from other events if Pearl Harbor hadnt happened. Like the sinking of the Repulse and Prince of Wales. 

True they would have eventually as I said, but some of those instances could be written off as perhaps crew was incompetent, or poor AA, or those were land based planes and CVs can't carry those heavy bombers.

I have heard plenty of excuses that rationalized the BBs being the power and being safe from CVs, but Pearl Harbor was undisputed proof since you had multiple BBs and other ships sunk or damaged proving that indeed BBs were actually quite vulnerable from the air, plus you had the 2 BBs you mentioned, and also the crippling of Bismarck. Added all together even skeptics had to agree BBs were in grave danger. But without Pearl Harbor the other incidents would likely have been written off as sporadic unluck incidents.

Like Bismarck only sustained minor damage except for what happened with the jammed rudder, but it was surface ships who pushed it to the point where the crew finally had to Scuttle Bismarck it was not Aircraft.

I would have given  Naval planners maybe about a decade before realizing BB age was over if Pearl Harbor had not happened, maybe less though, it's just hard to say really.

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13 minutes ago, DeliciousFart said:

I'll quote myself from my own thread.

I'm not certain if the outer STS plating on the South Dakota and Iowa class was ever factored into immunity zone calculations, and I'm not even going to open the can of worms that is the question of decapping. The thickness increase of the outer hull plating was primarily due for structural strength reasons for the longer Iowa hull, and maybe better protection from shell splinters as well.

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4 minutes ago, Admiral_Thrawn_1 said:

True they would have eventually as I said, but some of those instances could be written off as perhaps crew was incompetent, or poor AA, or those were land based planes and CVs can't carry those heavy bombers.

I have heard plenty of excuses that rationalized the BBs being the power and being safe from CVs, but Pearl Harbor was undisputed proof since you had multiple BBs and other ships sunk or damaged proving that indeed BBs were actually quite vulnerable from the air, plus you had the 2 BBs you mentioned, and also the crippling of Bismarck. Added all together even skeptics had to agree BBs were in grave danger. But without Pearl Harbor the other incidents would likely have been written off as sporadic unluck incidents.

Like Bismarck only sustained minor damage except for what happened with the jammed rudder, but it was surface ships who pushed it to the point where the crew finally had to Scuttle Bismarck it was not Aircraft.

I would have given  Naval planners maybe about a decade before realizing BB age was over if Pearl Harbor had not happened, maybe less though, it's just hard to say really.

 

Pearl Harbor was a little written off because the BBs were stationary and not ready for action. The sinking of the Repulse and Prince of Wales shortly thereafter really got the attention of the world's navies as they were both alert, manuevering, throwing up AA, and still got sunk by air power alone.

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17 minutes ago, 1nv4d3rZ1m said:

You know both the Yamato and Musashi both got hit by individual submarine torps on separate occasions right? And both times the TDS failed to protect the ships, the Yamato even suffered a main battery magazine flooding. Seems like it was flawed enough. 

Did not say she was not without flaws, but that she was not completely flawed in the torpedo armor protection. 

If you look at the armor belts on ships they often had to be joined some how and there could sometimes be weakspots depending on how  it was done. 

I will have to look at Yamato armor layout again, but if my memory serves me as well as it normally does let's just say you will not want to hit her with Deep Water Torps because those will likely hit the good armor unlike the the normal runnng depth Torps lol.

And main magazine flooding could possibly have been built in safety mechanism to prevent detonation in the event the armor was breached in certain ways.

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7 minutes ago, bsbr said:

What is up with you fawning over the Iowa and USN BB?

There's so much myth and rah rah about how great the Iowa is and how it's the best BB ever build that no one even cares about its dangerous flaws and pointing them out just gets buried by hatred on this forum. I'll take Dr George Elder over your amatuer analysis attempt any day.

Really? Of course you'll appeal to authority when you can't make your own arguments. Your doctor pulls excerpts from secondary sources, such as Norman Friedman's book (which he doesn't even cite; speaking of which, does this article have any citations? There's no bibliography of any kind) and then writes an editorialized conclusion.

 

I don't "fawn" over the Iowa, and in fact I think her initial design requirements were rather questionable and results in a lot of tonnage just getting additional speed, when that tonnage could be used to create a more balanced ship if they were willing to relax the max speed to, say, 30 knots. I'll also say that against battleship caliber guns, USN WW2-era Class A performs worse than most contemporary cemented armor and nearly as poorly as Japanese VH due to the hardening depth specifications. So much for fawning...

  • Cool 1

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