I hope Rusty Battleship can confirm my understanding on how Iowa is structurally built.
First the side armor - The class A plates and B plates are keyed together and then have a backing plate of either 0.825 or 0.625" STS with 2" of cement inbetween. This backing plate stops at the lower edge of the class A plate. The bolts attaching the class A plate to the backing plate have thick rubber gaskets to help with shock forces. Then the entire system is buttressed from the main armored deck to the top of the triple keel. The buttress is bolted/riveted/ or welded to its adjacent plates from above, side and below so there is no natural weak spot that is waiting for failure. Is this correct?
Each torpedo bulkhead being a continous longitudinal bulkhead that is over 2/3rd of the ships length acts as a strength bulkhead to the ships box girder. The armor plates being interlocked will also act as a strength bulkhead as any hogging motion would place the plates into compression which these plates would resist considerably. Any sagging motion would place the plates into tension which would need to break the interlocking keys and the backing plates in order to sag significantly. Is this correct?
The main turrets and barbettes are supported by the keel which has transverse and longitudinal bulkheads underneath them. These structures help support the weight from underneath and to the ships sides. The upper decks do not have to support the weight of the turrets as they are not really attached. This off loads the upper hull structure from attempting to support their weight. They do play a role in keeping the barbette structure vertical being pressed up against them with a weather seal making up the last couple inches of space. So the upper strength decks support the barbettes and turrets from sideways motions and not up and down motion. Is this correct?
The keel is made up of the central "I" beam but additional "I" beams run parallel for the entire ships length. The triple bottom is made to the grillage system box grid with intercostal plates all bolted/riveted/or welded on all four sides to their adjacent plates again leaving no natural weak spot. Under each turret the supporting structure in effect gives the ship a quadruple keel under each turret. Is this correct?
Her hull girder as three upper strength decks being the main, second, and third decks in which the second deck is by far the strongest with the class b deck plates also being keyed together. Is this correct?
In effect her sides because of the fully developed side protection she has 8 strength bulkheads with the armored 3rd bulkhead being the strongest for longitudinal strength. Since this bulkhead also extends to the main armored deck it directly supports this upper strength deck. Is this correct?
The ship has three lower strength decks which make up her triple bottom. This box girder would be extremely difficult or resistant to bending forces such as hogging or sagging. This is one reason she tends to sink her bow in rough weather along with the bow does not have much buoyancy within it. Is this correct?
If her keel took some form of damage her sides and upper strength decks are so strong they can support her weight.
Case in point - Arkansas on test Baker at 0.22 seconds after detonation her keel was impacted with a force of 7,000 psi. Her superstructure was seen to collaspe at 0.38 seconds after detonation but this structure had been badly damaged by test Able.
Her keel is crushed into the hull in places over six feet deep. Both starboard propeller shafts and both rudders were ripped off her hull and are gone. The ship was lifted by the explosion into the air and was lost from sight 1 second after detonation. At some point when the water moving skyward slowed to a point it could no longer support her weight she fell upside down and landed on the sea floor smashing what was left of her superstructure into the mud. Her turrets are still within the barbettes but her keel at each of her turret locations shows that the keel was bent in and out about 2 feet. Even with a totally destroyed keel almost her entire ship length the ship showed no sign of bending, twisting, or distortion and is was found intact. The rivets and seams of her bottom plating suffered severe damage with most failing.
Arkansas suffered crush damage to her keel and not the typical hog/sag that would break the ship in half. In fact her side armor plates are only cracked on both sides in one place forward but not pulled apart. Even when the ship was essentially in mid air with a crushed keel and absolutely no support her upper strength decks did not bend. So what held Arkansas together? I have more detailed information on the damage at specific frames if you wish me to post it.
If my understanding of how Iowa is constructed is correct then it would be virtually impossible for the ship to suffer a total structural failure and break in half due to a conventional mine or torpedo exploding below her keel. Ships with fully developed side protection in this case suffer local crush damage to the keel which attempts to limit the size of the hole in the keel and her subdivision will contain flooding. A single conventional warhead will not destroy enough of her structural integrity so that the chance of a total structural failure seen in destroyer type ships is basically impossible.
Shock damage can be severe but she was built to withstand a shock of about 2,000-3,000 ft lbs. Is this correct?
First the side armor - The class A plates and B plates are keyed together and then have a backing plate of either 0.825 or 0.625" STS with 2" of cement inbetween. This backing plate stops at the lower edge of the class A plate. The bolts attaching the class A plate to the backing plate have thick rubber gaskets to help with shock forces. Then the entire system is buttressed from the main armored deck to the top of the triple keel. The buttress is bolted/riveted/ or welded to its adjacent plates from above, side and below so there is no natural weak spot that is waiting for failure. Is this correct?
Each torpedo bulkhead being a continous longitudinal bulkhead that is over 2/3rd of the ships length acts as a strength bulkhead to the ships box girder. The armor plates being interlocked will also act as a strength bulkhead as any hogging motion would place the plates into compression which these plates would resist considerably. Any sagging motion would place the plates into tension which would need to break the interlocking keys and the backing plates in order to sag significantly. Is this correct?
The main turrets and barbettes are supported by the keel which has transverse and longitudinal bulkheads underneath them. These structures help support the weight from underneath and to the ships sides. The upper decks do not have to support the weight of the turrets as they are not really attached. This off loads the upper hull structure from attempting to support their weight. They do play a role in keeping the barbette structure vertical being pressed up against them with a weather seal making up the last couple inches of space. So the upper strength decks support the barbettes and turrets from sideways motions and not up and down motion. Is this correct?
The keel is made up of the central "I" beam but additional "I" beams run parallel for the entire ships length. The triple bottom is made to the grillage system box grid with intercostal plates all bolted/riveted/or welded on all four sides to their adjacent plates again leaving no natural weak spot. Under each turret the supporting structure in effect gives the ship a quadruple keel under each turret. Is this correct?
Her hull girder as three upper strength decks being the main, second, and third decks in which the second deck is by far the strongest with the class b deck plates also being keyed together. Is this correct?
In effect her sides because of the fully developed side protection she has 8 strength bulkheads with the armored 3rd bulkhead being the strongest for longitudinal strength. Since this bulkhead also extends to the main armored deck it directly supports this upper strength deck. Is this correct?
The ship has three lower strength decks which make up her triple bottom. This box girder would be extremely difficult or resistant to bending forces such as hogging or sagging. This is one reason she tends to sink her bow in rough weather along with the bow does not have much buoyancy within it. Is this correct?
If her keel took some form of damage her sides and upper strength decks are so strong they can support her weight.
Case in point - Arkansas on test Baker at 0.22 seconds after detonation her keel was impacted with a force of 7,000 psi. Her superstructure was seen to collaspe at 0.38 seconds after detonation but this structure had been badly damaged by test Able.
Her keel is crushed into the hull in places over six feet deep. Both starboard propeller shafts and both rudders were ripped off her hull and are gone. The ship was lifted by the explosion into the air and was lost from sight 1 second after detonation. At some point when the water moving skyward slowed to a point it could no longer support her weight she fell upside down and landed on the sea floor smashing what was left of her superstructure into the mud. Her turrets are still within the barbettes but her keel at each of her turret locations shows that the keel was bent in and out about 2 feet. Even with a totally destroyed keel almost her entire ship length the ship showed no sign of bending, twisting, or distortion and is was found intact. The rivets and seams of her bottom plating suffered severe damage with most failing.
Arkansas suffered crush damage to her keel and not the typical hog/sag that would break the ship in half. In fact her side armor plates are only cracked on both sides in one place forward but not pulled apart. Even when the ship was essentially in mid air with a crushed keel and absolutely no support her upper strength decks did not bend. So what held Arkansas together? I have more detailed information on the damage at specific frames if you wish me to post it.
If my understanding of how Iowa is constructed is correct then it would be virtually impossible for the ship to suffer a total structural failure and break in half due to a conventional mine or torpedo exploding below her keel. Ships with fully developed side protection in this case suffer local crush damage to the keel which attempts to limit the size of the hole in the keel and her subdivision will contain flooding. A single conventional warhead will not destroy enough of her structural integrity so that the chance of a total structural failure seen in destroyer type ships is basically impossible.
Shock damage can be severe but she was built to withstand a shock of about 2,000-3,000 ft lbs. Is this correct?
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