WI Japanese plans to build the Yamato class got leaked?

Suppose that the Japanese plans to build the Yamato class(it’s specs etc) got leaked, how would everyone else respond to that? Would they axe all of their 14 inch-16 inch ships and rush to build 18 inch behemoths as well?
 
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It depends what details leak. The US knew the Yamato class was being built pretty much as soon as they were laid down. They knew the ships would be will over the 35,000 ton WNT size limit. And they knew that they were most definitely not mounting 14" rifles in accordance with the 2LNT (they thought it would mount 16" and was the impetus for invoking the escalator clause in the 2LNT). The only detail that wasn't known was that the guns would be 18.1".

And no, I don't believe that the US would ditch their 16" gunned ships. They still need to update their Battleline and can't afford the 3-5 year delay in designing an entirely new 18" gunned ship. Plus, the American 2700 pound APC shell offered performance on par with the Japanese 18.1".

The British may think twice about the KGV class though. You may see them make the decision to go with triple 15" instead of the quad 14"and otherwise leave the ships the same just to get something in the water faster than designing a whole new ship. The Lion class may be redesigned from 16* to 18", but I doubt it (again, they can't afford the delay).
 
It depends what details leak. The US knew the Yamato class was being built pretty much as soon as they were laid down. They knew the ships would be will over the 35,000 ton WNT size limit. And they knew that they were most definitely not mounting 14" rifles in accordance with the 2LNT (they thought it would mount 16" and was the impetus for invoking the escalator clause in the 2LNT). The only detail that wasn't known was that the guns would be 18.1".

And no, I don't believe that the US would ditch their 16" gunned ships. They still need to update their Battleline and can't afford the 3-5 year delay in designing an entirely new 18" gunned ship. Plus, the American 2700 pound APC shell offered performance on par with the Japanese 18.1".

The British may think twice about the KGV class though. You may see them make the decision to go with triple 15" instead of the quad 14"and otherwise leave the ships the same just to get something in the water faster than designing a whole new ship. The Lion class may be redesigned from 16* to 18", but I doubt it (again, they can't afford the delay).
They find out about EVERYTHING(the guns, the armour, the size etc), except for the effectiveness of the Yamato class in practice.
 
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Still doesn't change anything. Both the US and UK are pretty much locked into their building plans at this point. The only real change I see would be the KGV being 15" ships and the Iowa class remaining a 4 ship class with BB 65&66 remaining the first two ships of the Montana class
 
When is key. Let's assume when Yamato is laid down - Nov 1937. At that point, the KGVs are already laid down. Given the limitations of British turret design capacity, I cannot see them altering the KGVs - it would delay the KGVs and the 1938 battleship class (the Lions) at a time when the need for modern battleships is even more urgent.

I would say that the British change nothing about the KGVs or Lions. The KGVs are still fully competitive against the primary and secondary threats of German and Italy. Japan is just not a strategic priority in comparison. The Lions will struggle against the Yamatos via lack of armour, but their guns and shells are just about good enough, being optimised for belt penetration at medium ranges, in contrast to American practice. But they'll still be paused on outbreak of war because the priority will be for escorts.

The US's reaction, having more time, strategic depth and industrial capacity would be more interesting.
 
US might build the Iowas as 28 knot 18" designs as they were one of the preliminaries, or just one of the 28 knot with 12 16" guns alternatives. The Montana's also might not be switched for the last 2 Iowa's
 
How about a real left-field thought? The US bets both ways: build the Montana's and a theoretically cheaper alternative of a submarine class firing bigger warhead torpedos? Or is that completely impractical? Given the wifty performance of early war US torpedos, maybe it would be a bad bet, but then a newer torpedo might have different scrutiny during development. It's a theory..... ;)
 
How about a real left-field thought? The US bets both ways: build the Montana's and a theoretically cheaper alternative of a submarine class firing bigger warhead torpedos? Or is that completely impractical? Given the wifty performance of early war US torpedos, maybe it would be a bad bet, but then a newer torpedo might have different scrutiny during development. It's a theory..... ;)
Honestly, the bet they probably make, is to accelerate construction of the Essex class carriers in addition to the Iowa and Montana classes
 
When is key. Let's assume when Yamato is laid down - Nov 1937. At that point, the KGVs are already laid down. Given the limitations of British turret design capacity, I cannot see them altering the KGVs - it would delay the KGVs and the 1938 battleship class (the Lions) at a time when the need for modern battleships is even more urgent.

I would say that the British change nothing about the KGVs or Lions. The KGVs are still fully competitive against the primary and secondary threats of German and Italy. Japan is just not a strategic priority in comparison. The Lions will struggle against the Yamatos via lack of armour, but their guns and shells are just about good enough, being optimised for belt penetration at medium ranges, in contrast to American practice. But they'll still be paused on outbreak of war because the priority will be for escorts.

The US's reaction, having more time, strategic depth and industrial capacity would be more interesting.
I am thinking 1st January 1937.They find out via the schematics through espionage.
 
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Suppose that the Japanese plans to build the Yamato class(it’s specs etc) got leaked, how would everyone else respond to that? Would they axe all of their 14 inch-16 inch ships and rush to build 18 inch behemoths as well?
Maybe the UK looks at super charges and heavier shells for the 14" guns on the KGV class ?

Maybe the new shells have a higher ratio of metal to explosive. Perhaps they even feature modest amounts of tungsten or other exotic materials ?
 
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Maybe the UK looks at super charges and heavier shells for the 14" guns on the KGV class ?

Maybe the new shells have a higher ratio of metal to explosive. Perhaps they even feature modest amounts of tungsten or other exotic materials ?
That's basically what the USN did. They developed a Super Heavy 14" APC shell for the Standards that was about 100 pounds heavier than the old Mk8 shell (1500 pounds vs 1402 pounds). At the same time, the USN strengthened the barrels of their guns to allow them to use a larger powder charge so the heavier shells would be fired at a higher velocity than the lighter ones were. As for the design of the shells themselves, IIRC, the shells were made somewhat longer to increase the weight while still keeping the same size bursting charge
 
I'd say that the USA expidites development of an 18" gun--perhaps firing super-heavy shells. (That is a frightening concept!)
North Carolinas definitely get completed as designed.
South Dakotas are not yet laid down, but with the age of the battle line, some probably get built. (The USA, unlike Britain and Japan, still has a 12" gun ship in the fleet, as well as Texas, New York, and Oklahoma--all with triple expansion engines. Building two South Dakota class ships allows those 4 old ships to be replaced.
Along with the 18" gun, I think that a twin turret would be in the pipeline--a triple turret probably requires a wide enough ship that the Panama Canal is a concern,
What gets built is another story--but the guns get developed at the very least.
Iowas armed with 6 x 18" guns? Impractical, but might get done.
 
I agree with @RamscoopRaider , this means the Iowas are redone as the 12-gun, 28-knot ships that were considered. They'd still have a South Dakota armor scheme, but eh, can't win 'em all.
Depends, if you go with design 65C, well that did improve on the South Dakota Scheme, but had to go to 3 quad turrets to free up the weight, and make some TDS compromises. So keeping the South Dakota scheme is the lesser of several evils for a 45k ton design
 
I agree with @RamscoopRaider , this means the Iowas are redone as the 12-gun, 28-knot ships that were considered. They'd still have a South Dakota armor scheme, but eh, can't win 'em all.
I wonder a bit about what the USN might have done if they truly knew all the details about the Yamato class (ie the intricate details as to how the Armour plate was made.) I'm thinking they might have tried to replicate the exact composition of the Armour used by the the Yamato, and then test fire the 16" 50 cal against test samples. Maybe the approach might have been to issue super charges for use against the Yamato class only as an alternative to going to 18" guns ?
 
I wonder a bit about what the USN might have done if they truly knew all the details about the Yamato class (ie the intricate details as to how the Armour plate was made.) I'm thinking they might have tried to replicate the exact composition of the Armour used by the the Yamato, and then test fire the 16" 50 cal against test samples. Maybe the approach might have been to issue super charges for use against the Yamato class only as an alternative to going to 18" guns ?
Problem is Yamato's plate is so @#$% inconsistent. You had one plate tested post war that was thickness for thickness the best the US had ever seen, right next to another at risk from being penetrated by 12" guns. Japanese QC had real issues

Super Heavy shells were already in the pipeline, and given desire for a somewhat balanced ship plus the realities of US obstructionist, 18" gun probably has to wait until BB-65 anyways
 
Plus, they'd need to build new 18" guns, while the 16"/50 is already available (well, until the communication snafu between BuOrd and C&R; it's amazing no heads rolled for that screwup).
 
Plus, they'd need to build new 18" guns, while the 16"/50 is already available (well, until the communication snafu between BuOrd and C&R; it's amazing no heads rolled for that screwup).
If heads weren't gonna roll over the torpedoes, they weren't gonna roll over a gun mix up. And considering that the 16"/50 Mark 7 was one of the finest naval rifles ever to go to sea, I think they're allowed a pass on this one
 
If nothing else I think it ensures that Britain completes Lion and Temeraire and that Vanguard is a Lion. Britain needs a counter to the Japanese ships and the Lion's are the best they can build fairly quickly.
 
If nothing else I think it ensures that Britain completes Lion and Temeraire and that Vanguard is a Lion. Britain needs a counter to the Japanese ships and the Lion's are the best they can build fairly quickly.
Yep.. Although if the UK had reason to believe that at least some of the armour of the Yamato class might have been vulnerable to 14" shell fire that might have changed their priorities some what ?

That being said I suspect there would have been a lot of pressure within the UK to build a class of battle ships that was seen as a more effective counter to the Yamato class. This might have had some interesting ripple effects.
 
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