World War II Battleship on Battleship Engagements

Richard Santos said:

Yamato's TDS was the only WWII era TDS design that failed to take advantage of elastic deformation theory and membrane deformation theory. Yamato's TDS was also the only one which failed to take advantage of the role of liquid loaded compartment in increasing the effrctivess of TDS and decreasing the listing moment generated when TDS is hit.

Prince of Walse and Pennsylvania were crippled by torpedo hits on propeller shafts, and Bismarck by a hit on the rudder. so neither speak to the effectiveness of the TDS. Wreck examination shows neither bismarck's nor POW's Torpedo bulkheads were ruptured. This shows their TDS were successful.

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That doesn't mean that Yamato's TDS is ineffective. The fact that no US BB was sunk underway is not due to a superior TDS only that there was a larger battlefleet screening them so that they get torpedo less.

The bunker fuel in the torpedo bulkhead as dampers were typically not replenished with sea water as intended as the fuel was spent. so in practice there isn't much difference between a bunker fuel assisted TDS or not.

the internal TDS used by the British, German and the US in their treaty battleships suffered from smaller protected area than the torpedo bulges used on the Japanese ships. It is relatively easier to have a torpedo not hit them as shown on the POW, West Virginia, Bismark and hit somewhere else.

The Yamato's bulkheads were armored and therefore not elastic. This was done to resist spall and sharpenel from penetrating the internal bulkheads like a shot gun. The understanding that the yamato's bulkhead was too rigid and did not elastically defrom is by USS Skate torpedoing the Yamato causing a 11m diameter hole / deformation with 3000 ton of water intake. It is also true that the elastic and fuel oil filled USS North Carolina TDS was punch through by a torpedo on Sept 15, 1942 which created a 36 ft hole / deformation (~12m). This made her lose 150,000 gal of fuel and to correct list, she was counter flooded thus reducing her max speed to 18 knots from 28 knots.


The fact is both system did work, though the designer of the Yamato expected more resistance. IIRC Yamato did not lose speed after the torpedo hit as it was an external blulkhead not an internal one. i.e. minimum counter flooding is required. In her final battle, it took 4 torpedo to start to reduce Yamato's speed.

I am not saying that the Yamato's TDS is good, it did its job and with all engineering solutions, there are trade offs. There is a reason why the TDS on the planned USS Montana went to a more Yamato design with a outward bulge and an inner armor plate. Now American welding technology in 1945 would be much better than Japanese riveting technology in 1937. Point I am making is, the internal system is a compromise based on the Washington treaties, Yamato's design is not inherently flawed, but the technology to make it is not there yet.


You can't really compare and say one design is better.

FORBIN said:

I don' t argue i understand fine gents but seems yes Yamato design etc... is less modern than Iowas and even eventualy precedent classes but this enomous War machine still amazing ! and as passionate we love these terribles machines !

A little comparison Kongo was a honnest BB in fact Battle Cruiser fast but not very well protected used especialy for escort the Kidō Butai/ 1st Air Fleet the first dedicated Air Naval Force never created,
Kongo do 32000 t It looks almost like a dwarf ! and Suzyua one of the superb Japanese heavy cruiser still 15000 t

Yamato is especialy impressive for its width and main turrets size a monster ! in addition a look enough unusual small island elegant, Iowa very long and very" slender".

Why Yamato also width there are a lot of room around turrets a reason ?
How many rounds for main turrets for Yamato and Iowa please ? i think at less 1000.

View attachment 38135

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Forbin, Yamato carried around 100 rounds per gun, i.e. roughly 900 rounds total. max would be around 120 rounds per gun.

There are 2 school of thought in aspect ratio design. the bismark and yamato is beammy because they had to reduce overall draft of the ship. this way they also produce very stable gun platforms but the ship have a slightly more pronounced roll. The British and American flavored narrower ships due to canal locks restrictions (also why they don't like torpedo bulges) and for the structural integrity of the hull. basically as the hull is deeper, it becomes a stronger beam as its moment of inertia is larger. therefore you need less structural strengthening i.e. weight. the ships pierce the waves more for better controllability in heavy seas but they make very wet bows.

Here is the extreme end of wave piercing design


and the extremely beammy design

Lezt said:

Forbin, Yamato carried around 100 rounds per gun, i.e. roughly 900 rounds total. max would be around 120 rounds per gun.

There are 2 school of thought in aspect ratio design. the bismark and yamato is beammy because they had to reduce overall draft of the ship. this way they also produce very stable gun platforms but the ship have a slightly more pronounced roll. The British and American flavored narrower ships due to canal locks restrictions (also why they don't like torpedo bulges) and for the structural integrity of the hull. basically as the hull is deeper, it becomes a stronger beam as its moment of inertia is larger. therefore you need less structural strengthening i.e. weight. the ships pierce the waves more for better controllability in heavy seas but they make very wet bows.

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Thank you, yes i see here a good site
for Iowa 1200 rds


Montana planned beat sure Yamato ? or even the Super Yamato modified with 510 mm guns ?

Lezt said:

That doesn't mean that Yamato's TDS is ineffective. The fact that no US BB was sunk underway is not due to a superior TDS only that there was a larger battlefleet screening them so that they get torpedo less.

The bunker fuel in the torpedo bulkhead as dampers were typically not replenished with sea water as intended as the fuel was spent. so in practice there isn't much difference between a bunker fuel assisted TDS or not.

the internal TDS used by the British, German and the US in their treaty battleships suffered from smaller protected area than the torpedo bulges used on the Japanese ships. It is relatively easier to have a torpedo not hit them as shown on the POW, West Virginia, Bismark and hit somewhere else.

The Yamato's bulkheads were armored and therefore not elastic. This was done to resist spall and sharpenel from penetrating the internal bulkheads like a shot gun. The understanding that the yamato's bulkhead was too rigid and did not elastically defrom is by USS Skate torpedoing the Yamato causing a 11m diameter hole / deformation with 3000 ton of water intake. It is also true that the elastic and fuel oil filled USS North Carolina TDS was punch through by a torpedo on Sept 15, 1942 which created a 36 ft hole / deformation (~12m). This made her lose 150,000 gal of fuel and to correct list, she was counter flooded thus reducing her max speed to 18 knots from 28 knots.

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The fact is both system did work, though the designer of the Yamato expected more resistance. IIRC Yamato did not lose speed after the torpedo hit as it was an external blulkhead not an internal one. i.e. minimum counter flooding is required. In her final battle, it took 4 torpedo to start to reduce Yamato's speed.

I am not saying that the Yamato's TDS is good, it did its job and with all engineering solutions, there are trade offs. There is a reason why the TDS on the planned USS Montana went to a more Yamato design with a outward bulge and an inner armor plate. Now American welding technology in 1945 would be much better than Japanese riveting technology in 1937. Point I am making is, the internal system is a compromise based on the Washington treaties, Yamato's design is not inherently flawed, but the technology to make it is not there yet.

You can't really compare and say one design is better.



Forbin, Yamato carried around 100 rounds per gun, i.e. roughly 900 rounds total. max would be around 120 rounds per gun.

There are 2 school of thought in aspect ratio design. the bismark and yamato is beammy because they had to reduce overall draft of the ship. this way they also produce very stable gun platforms but the ship have a slightly more pronounced roll. The British and American flavored narrower ships due to canal locks restrictions (also why they don't like torpedo bulges) and for the structural integrity of the hull. basically as the hull is deeper, it becomes a stronger beam as its moment of inertia is larger. therefore you need less structural strengthening i.e. weight. the ships pierce the waves more for better controllability in heavy seas but they make very wet bows.

Here is the extreme end of wave piercing design

and the extremely beammy design

Click to expand...

I didn't say yamato's TDS was ineffective. Effectiveness is measured against design goals. In that it generally met design goals, it was effective.

What I said was yamato's TDS was inefficient. Yamato's TDS design resistance goals were modest by 1938 standards, and less stringent even then some of the 35,000 ton treaty battleships. Yet the weight and space consumed by Yamato's TDS was high. So the TDS made heavy imposition on the ship's weight and space allotment for modest results. It was inefficient.

The fuel bunkers in liquid loaded TDS in other navies were designed to be filled with sea water as the fuel is consumed. In fact these tanks are equipped with centrifuges to separate sea water from oil so that sea water can be allowed to flood the tank even as there still remain oil in the same tank without contaminating the oil line and boiler burner. They were not left empty. Being liquid loaded was an integral part ofmthenTDS design and the TDS would have been much weaker if liquid loaded spaces were voided.

The Notion that TDS on the Bismarck, Pennsylvania and POW were shorter and therefore left propeller shaft and rudder exposed is completely without merit. No battleship had any form of torpedo protection for exposed propeller shaft and rudder. In fact, as a percentage of her overall length, yamato's TDS were shorter than those of most other battleships of the era, and left more of her hull unprotected.

It is also baseless to say Yamato had external torpedo bulge while Britis German, german and American battleship had internal TDS. All WWII battleships, including Yamato, had integral bulges that are structurally part of the hull. So they all had internal TDS. The fact that the top of the TDS pinches in does not mean true bulge is external. The pinch in is a design solution to accommodate an inclined armor belt that tilts inwards from the widest part of the ship, thus requiring the underwater hull to pinch in to meet it. British and German battleships had vertical belts, hence no need to pinch in the top of the TDS. American battleships, like Japanese battleships, had inclined belts, hence the pinch in on the North Carolina class.

Regarding the absence of pinch in on the Iowas, it is there. But in late stage of the design it's was decided to plate over the gap between the top of the belt and the top of the TDS, hence creating a illusion the hull continues straight down into the skin of the TDS. This is made clear if you look at the TDS design of the preceding South Dakota class. South Dakota class has precisely the same TDS design as the Iowa class. But on the South Dakota the top of the pinch in is left as is, so you can clearly seed where the torpedo bulge is. On the Iowa, it was determined that adding a layer of skin outside the main armor belt can enhance the effectiveness of the belt by de-capping APC rounds, so the decision was made to plate over the gap between the top of the armor belt and the top of the TDS.

Regarding Montana having Tamato like bulge, you are probably completely deceived by the misconception that the pinched in top signifies a different style of TDS then smooth vertical side. Montana's TDS is not Yamato like. It is a modified version of the North Carolina class TDS. I will describe the design history of American TDS in the next post

Here is a little bit of history of American battleship TDS development.

When the US started building battleships again after the end of battleship holiday imposed Washington treaty, the navy conducted an extensive series of Cassion tests, and determined a liquid loaded TDS, backed by thin elastic steel membranes, offer the most efficient absorption of torpedo explosion. The first new US battleships, the North Carolina class, adopted this design. This design was generally found to be satisfactory both in tests and in the only instance when an new American battleship was torpedoed in battle.

After the design of North Carolina was completed, US naval intelligence discovered that Japanese naval gunnery doctrine called for shells that, when fired at long range and impacted the sea short of target, were designed to have stable trajectories underwater so it can strike the enemy ship much lower down then is normally covered by a battleship's armor belt.

In response to this discovery, the US navy arrived at precisely the same solutions to this gunnery protection problem that the Japanese adopted on the Yamato, which was to extend the main belt downwards in a tapering way all the way to the ship's bottom. This is why the next two classes of American battleships, the South Dakota and Iowa, had similar side belt arrangement as the Yamato, with a sloping belt extended all the way to the ship's bottom.

The redesign of the TDS on the American battleships were hurried, and no cassion tests were carried out before South Dakota's were well along in construction. When the cassion tests were carried out, the USN was shocked and chagrined to find putting the rigid armor belt behind the TDS greatly and unexpected worsened the performance and effectiveness of the TDS. By then it was too late to change the design of the Iowa class as well. So the USN fought WWII with the knowledge that both South Dakota and Iowa class BBs had severely defective torpedo defense systems that were not tested prior to installation, and had performance much lower than design goals.

Incidentally, the same thing that made the TDS on the Iowa and South Dakota defective was also intrinsic to the TDS design of the Yamato.

With Montana, the US navy abandoned the somewhat Yamato like TDS designs of the preceding Iowa and SOuth Dakota classes, and reverted back to the original design used two classes ago, on the North Carolina class.

Incidentally, the steel armor behind Yamato's TDS was not there to catch shot gun blast of the torpedo fragments. The torpedos do not travel nearly fast enough for the splinters to have a shot gun effect. In any cases, the rigid armor backing behind Yamato's TDS was up to 8" thick and made of armor steel. It only takes 1-2" of structural steel to stop torpedo splinters. The reason why the TDS was backed by this lower belt was because the Japanese had a strong expectation that shells falling short could travel a long ways underwater and strike the ship's underwater side. The armor was there to stop deep diving shells.

In reality, during all of WWII, their was only 1 instance when a heavy caliber shell managed to truly follow such a long underwater trajectory to hit a ship deep under water.

FORBIN said:

Why Yamato also width there are a lot of room around turrets a reason ?
How many rounds for main turrets for Yamato and Iowa please ? i think at less 1000.

View attachment 38135

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Yamato is actually not extraordinarily wide for her size. Her beam of 38 meters is only 2 meters wider than bismarck's 36 meters, and she weigh 40% more than Bismarck. British and American battleships are unusually narrow, being 32 and 33 meters wide respectively. British battleships are restricted by the width of graving docks in Malta and Gibraltar, while American battleships are limited by the locks of Panama Canal.

Yamato has an usual hull form. She has relatively high block coefficient, which means her hull form is somewhat closer to a rectangular block than might be judged ideal for low resistance, This is necessitated by length and width resurrections of Japanese docks and depth of major Japanese naval bases. However, she has very advanced hydrodynamic features such as a bulbous bow that is perhaps 30 years ahead of its time. So although her hull form isn't ideal from block coefficient perspective, it is still hydrodynamically quite efficient.

You can see this from the fact that although Yamato was designed for 27 knots, she achieved 28.06 knots on just over 155,000 shp during a post refit trial in 1942. USS Montana, very similar in size and have better block coefficient, was calculated to need 180,000 shp to achieve 28 knots, while the Soviet Union's sovietskii soyuza class, slightly smaller, was calculated to need 220,000 to achieve 28.5 knots.

One more detailed difference the discussion about how many shells Yamato carry per gun compared to, say Iowa.

Yamato has a full mechanized shell and powder loading system that pulls each round and power charge from using pure machine power. Iowa's lower shell handling room is partially manual, requiring sailors to use muscle power and ropes combined with powered capstans to parbuckle shells into the hoist. So arguably in a sustained engagement the Yamato can keep up full rate fire for longer. Conversely Yamato only stow half of her shells in the turret rotating structure accessible by the power loading system. The other half is stowed in a lower magazine outside the barbette. The shell stowed outside can't be readily loaded into the hoist, and must first be manually moved into the rotating structure, before becoming accessible by the hoist. So Yamato only has 50 rounds per barrel ready for each engagement. Afterwards it must withdraw to refill its rotating shell rooms. Most other battleships can access their entire shell loads in singke engagement.

Richard Santos said:

One more detailed difference the discussion about how many shells Yamato carry per gun compared to, say Iowa.

Yamato has a full mechanized shell and powder loading system that pulls each round and power charge from using pure machine power. Iowa's lower shell handling room is partially manual, requiring sailors to use muscle power and ropes combined with powered capstans to parbuckle shells into the hoist. So arguably in a sustained engagement the Yamato can keep up full rate fire for longer. Conversely Yamato only stow half of her shells in the turret rotating structure accessible by the power loading system. The other half is stowed in a lower magazine outside the barbette. The shell stowed outside can't be readily loaded into the hoist, and must first be manually moved into the rotating structure, before becoming accessible by the hoist. So Yamato only has 50 rounds per barrel ready for each engagement. Afterwards it must withdraw to refill its rotating shell rooms. Most other battleships can access their entire shell loads in singke engagement.

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Very interesting, exist interiors view of Yamato's turrets ? and what is it exactly this " computers " have Iowa possible others US i think a rustic computers to this time very few electronic existed ( i know B-29 have a system enough special maybe comparable to Iowa )
I see armoring do 40% of the tonnage for Bismarck similar for Iowa, Yamato surely at less 30 % ?


Thanks to all for these things

Also some links


Task Force 34's Moment of Glory:
An exploration of what might have happened


And yes finaly to some hours the great what if could have taken place

Size comparison

FORBIN said:

Very interesting, exist interiors view of Yamato's turrets ? and what is it exactly this " computers " have Iowa possible others US i think a rustic computers to this time very few electronic existed ( i know B-29 have a system enough special maybe comparable to Iowa )
I see armoring do 40% of the tonnage for Bismarck similar for Iowa, Yamato surely at less 30 % ?


Thanks to all for these things

Also some links

Please, Log in or Register to view URLs content!

Task Force 34's Moment of Glory:
An exploration of what might have happened

Please, Log in or Register to view URLs content!

And yes finaly to some hours the great what if could have taken place

Click to expand...

If I recall, yamato's total weight of armor is around 23000 tons, which as a percentage of the ship's overall weight, was not particularly high, and lower than those of Bismarck. But Yamato was designed to different principles than the Bismarck.

Basically, Yamato was designed to concentrate all of the ship's vital spaces into the most compact possible arrangement and form a impregnable citadel, so that the area that needs to be armored is as small as it can be. This is the reason why yamato's superstructure seem so small and the main and secondary turrets seem piled up into just a small part of the ship. This enable these vital spaces to be protected by a simple arrangemet consisting of single layers armor of maximum possible thickness. In fact single layer of thick cemented armor offer better protection than multiple layers of thinner armor adding up to the same thickness and weight. So yamato's main armor belt, and her TDS, is only about 50% as long as the ship. But Yamato has the thickest deck and thickest side armor of any modern battleship. Yamato was also carefully designed so that the portion of the ship that were protected by heavy armor and TDS was just large enough so that if the unprotected parts of the ship was fully riddled, the protected citadel, if not breached, would still have just enough buoyancy to keep the ship afloat and navigable. This concentration of vital assets and protection into a compact citadel is what allowed Yamato to have immensely strong protection for all her vitals while still keeping the percentage of weight devoted to armor at moderate level for her size.

What ultimately did in both,Yamato and musashi was while their central citadels were very strongly protected, the protection did not prove to be 100% impregnable. The TDS even on the musashi was largely effective but not 100% effective and at least one of the engine rooms were breached. So the buoyancy offered the damaged citadel was no longer sufficient to keep the ship afloat once the unprotected part of the ship became riddled and the flooding in those parts can't be controlled.

Bismarck was designed to a different principle all together. Bismarck accepted that multiple layers of armor might offer less protection than a single layer of armor of the same total thickness. But multiple layers of armor could be cleverly arranged to offer good protection for the most critical areas, while still offer significant protection to a lot of less important areas. So unlike the Yamato, where alsmost everything critical for the ship to stay afloat and fight is protected by single layer of armor designed to resist 18" shells, Bismarck protected those absolutely critical for the ship to remain afloat by one or more layers of armor which combine to resist 16" shells, but left many more things good for fighting but not vital for survival with layers of thinner armor design to resist 8" shells. So while the absolute vitals have good if not the strongest possible protection, much more of the ship has at least some protection. Furthermore the Germans didn't believe in protecting just enough of the ship's buoyancy so the ship would remain afloat. Possibly this is because the Germans forsaw that no protection is completely impregnable, and if a ship only protect just enough buoyancy for the ship to survive, and that protection is breached, then the ship would likely be lost. Instead the Germans designed the Bismarck to protect as much of her bouyancy as possible. Hence Bismarck' armor belt and TDS covered almost 75% of the ship's length.

Hence although nowhere on the Bismarck does the armor protection approach the level offered by the armor around yamato's citadel, much more of bismarck's hull has some respectable level of protection. Hence bismarck's armor weight represent a higher percentage of her weight than yamato's.

Richard, I don't disagree with your assessment. there is just nuances with how you would define effectiveness against design goals versus what I would call effectiveness against actual received threats.

I don't know how you factor in weight and space; as technically, it provides additional buoyancy. As pressure wave from an explosive charge is a cubic function and the strength of materials is a square function, a system designed to resist larger explosions would be exponentially heavier/bulkier.

The Yamato was designed to resist a 400 kg TNT charge
The Bismark was designed to resist a 250 kg TNT charge
The IOWA/North Carolina was designed to resist 700 lbs TNT charge (317 kg)
The KGV was designed to resist 1000 lbs TNT (453 kg)
The Vanguard was designed to resist 1100 lbs TNT (498 kg)

So by your definition, KGV's system would be fairly crap as POW took significant damage with Type 91 235 kg warhead torpedos which is significantly under its design resistance? The Bismark's TDS is reasonable as the 18 inch Mark XII 176 kg warhead is under its design limit. While the Mark 13 with 270 kg Torpex (say eqv. 405 kg tnt, as torpex is from late 42), would be right at the limit of Yamato's design

Obviously the bulge that the yamato had is integral part of the hull unlike the ones fitted onto the nagato post refit. What I meant by external as is that that portion of the hull is discounted or not considered vital for buoyancy, unlike the *internal* ones which do. but this is semantics, just like how US design philosophy is that the reserved buoyancy inside the armored citadel must be sufficient to keep the ship afloat as both ends of the ship is flooded completely versus if the Japanese / German philosophy which does not as the ends will still trap air as it is flooded.

Also, I did not say that bismark and POW didn't have TDS over the propeller shafts / rudder. What I meant was that it is not just one torpedo that hit Bismark and POW took 5 and 7 respectively; and one of those torpedo took out the rudder / propeller shaft. i.e. the rest landed elsewhere on the ship and some must be on the belt. What i meant was that the Yamato's were deep. from: Jospeh Czarnecki´s"Torpedo Defense Systems of World War 2"

"...Despite all of the design features intended to moderate the effects of a torpedo hit, the single most important factor in the effectiveness of a TDS remained its depth. The greater the distance between the point of impact on the side shell and the holding bulkhead, the more likely the system would protect the interior compartments. The French battleships of the Richelieu Class are often credited with the most effective TDS, but this is largely due to its extreme depth amidships. In other respects the design was very conventional.

Even in the Richelieu Class, the depth of the system was not constant from bow to stern, tending to taper and thin out toward the ends. This was also where it was least affordable: near the magazines. This factor also compromised the highly effective TDS fitted in the American fast battleships. The demands of high speed dictated that US fast battleships be very fine forward, thus restricting the depth available to the torpedo defense system abreast the forwardmost turret. This reduced the system’s effectiveness, with the result that the flash from a torpedo’s blast reached the forward magazine of USS North Carolina (BB-55). Flooding from the hit fortunately prevented a fire. The demands of high speed also dictated a complex stern structure that restricted and weakened the TDS in the South Dakota class aft... "

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As multiple impact happened, no one knows how well they perform as none of the belts were designed for multiple impacts. The unmanned submersible vehicle which explored the wrecks of Bismark and POW cannot possibly see deep inside as clearly as battleships which returned to dry dock.

I think, what I am trying to say here is. it seems like you are looking at the designs through a more American design perspective. Which is fair, but we must remember that British Department of Naval Construction thought US BB designs were crap, while the US Bureau of Construction and Repair thought British BB designs were crap. The Arberdeen proving ground thought the soviet T34 tank was crap; while the Germans, Heinz Guderian; thought it was great and wanted to copy it into the VK3002(DB). The Austrians thought the Bayerns were crap and the Germans thought the Viribus Unitis was crap. - where *crap* is a statement of less than ideal design. Thus, if we change the assessment criteria, is the assessment so clean cut?