World War II Battleship on Battleship Engagements

Richard Santos said:

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.

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I have see this expression for armoring/protection " all or nothing " it is clear as for tanks the formula is mobilty, protection, firepower and impossible have all especially for armoring buid a ship to 100000 t she get slow or increase propulsion but same again more heavy, for tanks Panther had the best compromise.

On graphics i don' t see the Yamato's citadel much more small than Iowa mainly the part between last main turret and propulsion, propeller significative ? exist same similar graphic for Montana ?

Lezt said:

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
?

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Seems - maybe coz only 2 battles between BB - BBs clearly more vulnerable to torpedoes - in more Ironically arming more small combattants -and i think armor mainly oriented against shells, bombs but TBS, armoring under the waterline was significant so an impression or the true ?

Other thing with previous post all the tanks for the fuel are external in the anti-torpedo bulge ? and only BBs have anti-torpedo bulge ?

I learn much with you two

FORBIN said:

I have see this expression for armoring/protection " all or nothing " it is clear as for tanks the formula is mobilty, protection, firepower and impossible have all especially for armoring buid a ship to 100000 t she get slow or increase propulsion but same again more heavy, for tanks Panther had the best compromise.

On graphics i don' t see the Yamato's citadel much more small than Iowa mainly the part between last main turret and propulsion, propeller significative ? exist same similar graphic for Montana ?

View attachment 38192 View attachment 38193

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Iowas are an highly unusual battleship design that is completely outside the mainstream of American battleship design, or anyone else's for that matter. The post War longevity of the Iowa class somewhat obscured that and turned them into not only a typical, but supposedly very good, battleship design in popular minds.

In 1937 Existing US battleships could barely do 21 knots and the new North Carolina and South Dakota classes were designed to reach 28 and 27 knots respectively, and there were doubts they could do so well in service because of the compromises made in their hull forms and sea keeping capability to keep them under the 35,000 ton treaty tonnage restriction.

The Iowa design was born when the USN became aware that the Japanese Kongo class battlecruisers were heavily modernized and can reach over 30 knots. USN planners did some war games and concluded despite the relatively weak firepower and protection of the Kongos, their speed makes them a tremendous threat because they can operate independently as fast raiders, avoid any us battleships, and destroy any us cruisers, and basically cut American supply lines from Hawaii to the west pacific, and prevent us cruisers and destroyers from properly scouting.

So when the treaty tonnage limit increased to 45,000 tons, the USN decided that, rather than build a stronger battleship than the preceding South Dakota class, they should build a 33 knot version of the South Dakota. This was how Iowa class was born.

Basically, the USN took the South Dakota design, stretched the central armored portion just enough to install boilers and turbines that were 80% more powerful. They then took the unarmored front and back portion of the hulls, stretched them until they were long enough to obtain the proper length to beam ratio required for the hull to be able to reach 33 knots with new power plant. As it turns out, the amount of stretching needed to get the hull to efficient go through the water at 33 knots was much greater than the amount of stretching needed to install that larger power plant.

Hence Iowa class has comparatively a short citadel in a long hull. Although it is about as long as the Montana class, iowa's citadel is much shorter and more thinly armored.

The Iowa class weighed 45,000 tons, and were not particularly well armored, and had a seriously defective torpedo defense system design made worse by the need to taper the hull width down for hydrodynamic efficiency abreast the A turret. So the torpedo protection for A turret magazine is barely existent. There were and remain serious doubts about the structural strength of their long, very slim bow. It is believed a torpedo hit forward of the A turret may cause the entire bow to fail structurally and break off, which, while not fatal to the ship, certainly compromise the ship's ability to remain in the battle line. Although they were fantastically fast, they were poor sea boats, rolled a lot in heavy seas for a ship their size, was very wet just aft of B turret, and had more severe speed restriction in heavy seas then seem appropriate for ships of their size.

By middle of the war, after cancelling the montanas, USN had also internally acknowledged the Iowa class design had made too much compromises to achieve their speed, and the design would not be repeated in any future battleship project even though there is now all the more emphasis on fast battleships to escort fast carriers, and only the Iowa class were truly fast enough for the role. At the time there were still thought of fast post war battleships as powerful carrier escorts. The USN decided the follow on design should have similar firepower and armor as the Iowa, same engines, but new hull form that is less hydrodynamically efficient but better shaped to protect the A turret magazine against torpedos, which would reduce their top speeds to 30 knots.

Richard Santos said:

Iowas are an highly unusual battleship design that is completely outside the mainstream of American battleship design, or anyone else's for that matter. The post War longevity of the Iowa class somewhat obscured that and turned them into not only a typical, but supposedly very good, battleship design in popular minds.

In 1937 Existing US battleships could barely do 21 knots and the new North Carolina and South Dakota classes were designed to reach 28 and 27 knots respectively, and there were doubts they could do so well in service because of the compromises made in their hull forms and sea keeping capability to keep them under the 35,000 ton treaty tonnage restriction.

The Iowa design was born when the USN became aware that the Japanese Kongo class battlecruisers were heavily modernized and can reach over 30 knots. USN planners did some war games and concluded despite the relatively weak firepower and protection of the Kongos, their speed makes them a tremendous threat because they can operate independently as fast raiders, avoid any us battleships, and destroy any us cruisers, and basically cut American supply lines from Hawaii to the west pacific, and prevent us cruisers and destroyers from properly scouting.

So when the treaty tonnage limit increased to 45,000 tons, the USN decided that, rather than build a stronger battleship than the preceding South Dakota class, they should build a 33 knot version of the South Dakota. This was how Iowa class was born.

Basically, the USN took the South Dakota design, stretched the central armored portion just enough to install boilers and turbines that were 80% more powerful. They then took the unarmored front and back portion of the hulls, stretched them until they were long enough to obtain the proper length to beam ratio required for the hull to be able to reach 33 knots with new power plant. As it turns out, the amount of stretching needed to get the hull to efficient go through the water at 33 knots was much greater than the amount of stretching needed to install that larger power plant.

Hence Iowa class has comparatively a short citadel in a long hull. Although it is about as long as the Montana class, iowa's citadel is much shorter and more thinly armored.

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I have see capable 33 kn especialy for escort Essex capable also 33 kn in more provide a robust AAW defense.

The idea that a carrier nominally capable of 33 knots would best be escorted by battleships also capable of 33 knots certainly sounded good to planners, but by 1944, the USN pretty much concluded a battleship around the size of Iowa, (45000-50000 tons) with similar armor (proof again 45 caliber, but not 50 caliber 16" gun at 20-30km) and gun power (16" 50 cal main gun and 20 medium caliber AA guns) and capable of 33 knots but also has satisfactory torpedo protection can't be built.

Incidentally, later in the war the Royal Navy and the USN developed widely divergent views of the level of torpedo and horizontal protection a battleship really required. The USN never either developed or was subjected to particularly heavy weapons designed to sink battleships. The USN was als accustomed to air superiority. So the USN felt the deck protection of the Iowas and something similar to the torpedo protection of the Montanas were adaquate. So the US navy felt an ideal post war battleship would be about 50,000 tons, 9X16 inch guns, 30 knots, TDS resistant t 1200lbs torpedo warhead, and 6 inches of deck armor.

The Royal Navy was subjected to German rocket boosted AP bombs, and dropped super heavy bombs on German battleships. So the brits felt the deck of any future battleship must resist 3,000 lbs rocket boosted AP bombs, similar to German Fritz-x glide bomb, and hence need to be about 12 inches thick, and the TDS must resist at least 2000 lbs torpedo warhead. As a result, RN design studies suggest even at 60,000 tons, a future battleship could only afford to mount 6X16" guns after accounting for all the protection. In other words, the brits felt for a battleship to be truly adaquately protected based war experience, an Yamato sized ship can only afford to mount 6 16" guns rather than 9 18" guns.

FORBIN said:

Seems - maybe coz only 2 battles between BB - BBs clearly more vulnerable to torpedoes - in more Ironically arming more small combattants -and i think armor mainly oriented against shells, bombs but TBS, armoring under the waterline was significant so an impression or the true ?

Other thing with previous post all the tanks for the fuel are external in the anti-torpedo bulge ? and only BBs have anti-torpedo bulge ?

I learn much with you two

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Battleship engagements were rare, but not that rare.

there is around 10 battle where a battleship / battlecrusier fired on another.



TDS starts to appear on everything as large as a cruiser.

I think around 80% of all ships sunk in ww2 was by torpedos. the reason is fairly simple, a torpedo hit generally opens a massive hole in the magnitude of 10 meters diameter that floods and therefore sink the ship quickly and there is nothing that damage control crew can do.

Gunfire doesn't really punch that many holes to allow water ingress and the majority is above the waterline. given that the magazine is well protected, unless a lucky shell blows it up, the ship won't really sink even if the superstructure is burning. you have to remeber how strong these ships were built. Yamashiro or Fuso, both sunk at the Surigao Strait. but the battleship stayed afloat after it was split into 2 parts and burned through out the night. if the bulkhead holds, the ship won't sink -> as in the case of the Bismark as well.

Ultimately, it is better not to be hit by a torpedo than to rely on the TDS

There was a belief that a ship as speed would not be hit by a submarine torpedo. There is some truth to this as subs are typically max 8 knots submerged, when even the older US line battleships can do 21 knots. Torpedos are running mostly between 30 knots, to 45 knots; and a range of 5 km. i.e. it is really hard unless the sub was already lurking there. And it changed with german wake homing torpedos and magnetic detonators (to detonate the torpedo under the keel of the ship to break its back). TDS became obsolete.

The next threat is by enemy FAC and destroyers; where the secondaries guns come in. Europeans and the Japanese chose guns one size up from destroyers to provide stand off distance from destroyers. while, the US chose to use the same size. basically, i would say that US BB are venerable to destroyer charges. hit probability statistics, a destroyer before being destroyed can get within torpedo range where the turning radius of the BB cannot avoid the launched torpedo. The bismark had a 150mm secondary , 105mm tertiary guns while the Nagato had 140mm secondaries, 125mm tertiary guns, the Yamato had 155mm secondaries and 125mm tertiary guns. they worked very well at keeping destroyers and FAC away for the Japanese and Germans.

The next threat is air attack. the US 5" works really well, and the german 105mm less so and the japanese 125mm guns not so much, and the british 5.25" is terrible. So american BBs are better protected for ww2 as aircraft can catch battleships and launch torpedo.

It is a very different philosophy. Germans capital ships often had to fight alone or in small groups. US capital ships always had a screen of destroyers and air cover, British capital ships often fought german wonder weapons that penetrates their protective screen and Japanese capital ships just didn't have quantity and technology to fight the US, so they have to try an make their ships best in a very singular role. i.e. the shells that over penetrate Taffy 3 were designed so that they would not explode on contact with the sea, but allowing it to travel under water and under the armor belt, their optical parallel correction device is more or less the best in the world and others.

So the German produced very well protected BB that can fight most engagement well. The US produced BB that fight ideally at long range (think about it, a light cruiser can shred the unprotected ends of a US BB; it will not sink, but it would have taken on so much water that it might do 5 knots). British BB are designed so that they can take more of a beating. Japanese BB are designed so that they can win a daylight open ocean line battle engagement.

The threat of an underwater shell hit is not that it would punch a very large hole. The threat results from the fact that the armor belt on most battleships prior to 1937 reach at most half way down the underwater hull, and beneath that there is effectively no armor. An shell falling short and following stable under water trajectory could in theory penetrate into a battleship's magazine by punching through just a couple of layers of shell plating, and encounter no armor whatsoever.

Prior the end of WWI, the range at which battleship actions were fought meant shells landing short tend to ricochet off of the surface of the sea rather than dive deeply and hit the ship underwater. So that was not a major concern.

In 1924, the Japanese did a series of ballistic tests on the incomplete new battleship Tosa, which was cancelled under the 1922 Washington treaty. One of the test shells did precisely as described above and penetrated Tosa below her armor belt and entered her magazine. It appears this result caused the Japanese navy to believe it had stumbled upon a battle winning secret. Through 1920-1930s, the IJN redesigned all their large caliber AP shells to enable them to follow stable underwater trajectories underwater rather than tumble through the water after falling short, and have them very long fuse delays so the shells don't explode prematurely after hitting water, but would instead have time to dive below the belt of enemy ships and penetrate deeply inside before exploding.

The Japanese put tremendous faith in the value of trying to land their shells just short attempt to penetrate enemy battleships below their armored belt, and developed a doctrine to fight gunnery action at long range to maximize the chance of plunging shots hitting the enemy below water rather than shallow shots ricocheting off the surface.

For the chance to score a silver bullet underwater hit at long range, the Japanese gave up a lot.
1. Japanese APC shells, by adopting a shape designed to ensure stable underwater trajectory, did not have the ideal shape for best ballistic performance in flight, nor have optimal shell weight for armor penetration.
2. To ensure the shell fuse gives the shell time to travel underwater into the enemy ship rather than exploding 3-4 meters after hitting the water, Japanese shells have far longer fuse delays than is aporopriate for any type of hit above water. Hence Japanese shells have a strong tendency to pass right through enemy ship and explode only after the shell had traveled a considerable distance out the other side. This greatly reduced the destructive potential of Japanese battleship shells for perhaps 99.5% of all hits.

I did not say that the Japanese long fused AP was designed to punch holes under the waterline, what I said was:

but allowing it to travel under water and under the armor belt

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It is also not that improbable, if you look at the damage done to Krishima Nov. 1942; out of the 20 16 inch gun hits on her, 7 was under the waterline, of the 7, one dud deep diving 16" shell took out the rudder. Had the 16" been long delay fuesed, it is very possible that more hits will occur deeper under the armour belt.


Ofcourse, if you look at the damage done to South Dakota, the 3 14" hits were all above water and the rest of the 27 hits, were mainly by 8", 6", 5" guns from crusiers were aiming high. Just as the 5" hits on the Kirishima was aiming high as per naval doctrine. which showed the disconnect between the idea of firing long delay 8" shells and the practice of hitting the superstructure as the cruiser armament was not expected to penetrate BB armor - which cause most of them to just pass through the superstructure.



So in summary, the theory and probability was sound. the execution was not.