WI: Shinano, Mutsu and an Unryu for Leyte Gulf

steamboy

Aye so now we have 3 issues that the IJN must solve before doing this.

1 - It needs to actually build the Shinano and finish it as a BB, but then what does this cost in terms of any other construction? This gets even worse if you somehow get the 4th built, because not only do you need steel, you need thick armour grade steel which is slow to produce, in addition to the hugely slow to make 18.1-inch guns.

2 - Getting all these carriers is great, where are you going to find the aircrews for them? The IJN lost its crop of pilots in the Mariana's turkey shoot, there's simply not the trained personnel to fill out the gaps even if there's decks available. You need the aircraft, the personnel and fuel for them. At the moment Japan has one of those things, the aircraft but even then these are mostly older aircraft that will later be used as Kamikaze's, not what you want to put a grossly inexperienced pilot into and then say "Go fight a Hellcat or Corsair." Because honestly it'll just be quicker to shoot the pilot there and then. At least it'll save you the fuel.

3 - Fuel. Yamato's were THIRSTY (think the internet thirsting over Lady Dimitrescu from Resident Evil and ramp it up from there) ships, they guzzled fuel, and it was one of the reasons they were not used earlier, they saw a fuel tanker, and other battleships went CHUG! CHUG! CHUG! CHUG! and so they did. Now you're ramping up the fuel issues with a 3rd or god forbid a 4th Yamato. If you deploy all 4, you might have to drain the tanks of other big ships, meaning they can't take part, and even then, its probably not going to be enough. You might have to drain the tanks of both Nagato's to get one of them fueled up, so then the point of having both is gone. Do you drain the fuel of the Ise conversions? Then your deception and decoy force is less tempting? Taking away fuel from the Fuso and Yamashiro? I'm sure Admiral Nishamura would love that if he had to only make that attack with the Mogami.
 
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NOMISYRRUC

ShySusan said:
My question is, if they keep building 110 and 111, what aren't they building instead? Were the Japanese able to use the resources freed up by suspending the two ships to build other, more vital ships like carriers, destroyers or tankers?
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steamboy said:
Yeah that's the big issue with the Yammy's, they consumed huge amounts of limited resources. Build them and other things will simply not be built.
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"If you've done six impossible things this morning, why not round it off with breakfast at Milliways, the Restaurant at the End of the Universe."

I thought, "What the hell! Let's do it!" Several implausible changes are required to make the OP work. What difference will one more make?
  1. Completing Shinano as a battleship in time to take part in Leyte Gulf is implausible.
  2. Completing another Unryu class aircraft carrier in time to take part in Leyte Gulf is implausible.
  3. I suspect that a secondary reason why Unryu and Amagi didn't take part in the the OTL battle was insufficient fuel. Providing the fuel for all the extra ships that @Kantai Kessen wants to join the battle ITTL is implausible. That's the fuel required for the ships to be worked up and for the crews to maintain their skills as well as the fuel for the battle itself.
  4. Training enough aircrew for all the available aircraft carriers is implausible.
    • That's partially because the Japanese have to expand their training programme much earlier than they did IOTL.
    • Then they need the fuel to train the pilots. See Point Three.
    • Finally, the expanded training programme has to cover the extra aircrew that would be lost in the softening up operations ( i.e. the raid on the Philippines in September 1944 and the Okinawa-Luzon-Formosa raid of October 1944) as well as provide enough aircrew for the extra aircraft carriers.
The only thing that's easy to do is not convert Ise and Hyuga into hybrid battleship-carriers because it's doing less than OTL instead of more.
 

steamboy

Don't forget that the Ise and Hyuga never actually carried planes or launched any. The conversions were done but they never carried an airgroup.
 

NOMISYRRUC

The one good thing is that had the Japanese been able to press on with the construction of Shinano from December 1940, she would have been launched in January 1943 instead of November 1944, which would have enabled the Japanese to lay down an extra aircraft carrier early in 1943.

Similarly had the Japanese been able to press on with the construction of No. 111 she would have been ready to launch around July 1943. IOTL her dismantling began in March of that year but we don't know when the slipway was cleared. So pressing on with her construction is unlikely to deprive the Japanese of a slipway.

However, Yamato was built in 5 years and Musashi was built in 4½ years. Shinano and No. 111 were laid down in May and November 1940 (according to Conway's 1922-46). If they took as long to build as Yamato they wouldn't be ready until May and November 1945 respectively. If they took as long to build as Musashi they wouldn't be ready until November 1944 and May 1945. By ready, I mean completed, not ready for action, because a few more months would have to be allowed for working up.

And it's unlikely that the aircraft carrier laid down early in 1943 would be ready in time to fight at Leyte Gulf.
 
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Kantai Kessen

Kantai Kessen

NOMISYRRUC said:
The one good thing is that had the Japanese been able to press on with the construction of Shinano from December 1940, she would have been launched in January 1943 instead of November 1944, which would have enabled the Japanese to lay down an extra aircraft carrier early in 1943.

Similarly had the Japanese been able to press on with the construction of No. 111 she would have been ready to launch around July 1943. IOTL her dismantling began in March of that year but we don't know when the slipway was cleared. So pressing on with her construction is unlikely to deprive the Japanese of a slipway.

However, Yamato was built in 5 years and Musashi was built in 4½ years. Shinano and No. 111 were laid down in May and November 1940 (according to Conway's 1922-46). If they took as long to build as Yamato they wouldn't be ready until May and November 1945 respectively. If they took as long to build as Musashi they wouldn't be ready until November 1944 and May 1945. By ready, I mean completed, not ready for action, because a few more months would have to be allowed for working up.

And it's unlikely that the aircraft carrier laid down early in 1943 would be ready in time to be ready in time for Leyte Gulf.
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TBH, I think the least implausible thing in this scenario, besides not converting Ise and Hyuga (which was stupid anyway IRL) and Mutsu not blowing up (which was a freak accident), is getting Shinano ready for combat by March 1944.

If the IJN realises that they have little hope of completing the vast fleet regeneration programme of RL, then they may focus resources into the ships that can be feasibly completed for a decisive battle/campaign in 1944. That means ships like Taiho and Shinano, which actually stand a fair chance of completion - thus we get faster construction and they can enter service more quickly.

I think the IJN's decision to build so many Unryus was foolish, and they'd have been better off with the resources they put in with three more Taihos. Is that possible?
 
Kantai Kessen

Kantai Kessen

steamboy said:
Don't forget that the Ise and Hyuga never actually carried planes or launched any. The conversions were done but they never carried an airgroup.
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For many good reasons. Whoever thought that was a good idea deserved to be shot. Waste of two perfectly good battleships.
 

NOMISYRRUC

steamboy said:
Don't forget that the Ise and Hyuga never actually carried planes or launched any. The conversions were done but they never carried an airgroup.
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I hadn't.
NOMISYRRUC said:
I think that converting Ise and Hyuga to hybrid battleship-carriers was a waste of resources even if the aircraft and aircrew had been available.
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The Unryu's had an overall length of nearly 750 feet.

A crude measuring of Ise's drawing in Conway's 1922-46 shows that the aft superstructure was about a third of the length of the ship or about 240 feet. Perhaps the resources steel used to for the conversions could have knocked a few months off the building time of Katsuragi which was under construction when the battleships were being converted.
 
Kantai Kessen

Kantai Kessen

steamboy said:
Aye so now we have 3 issues that the IJN must solve before doing this.

1 - It needs to actually build the Shinano and finish it as a BB, but then what does this cost in terms of any other construction? This gets even worse if you somehow get the 4th built, because not only do you need steel, you need thick armour grade steel which is slow to produce, in addition to the hugely slow to make 18.1-inch guns.

2 - Getting all these carriers is great, where are you going to find the aircrews for them? The IJN lost its crop of pilots in the Mariana's turkey shoot, there's simply not the trained personnel to fill out the gaps even if there's decks available. You need the aircraft, the personnel and fuel for them. At the moment Japan has one of those things, the aircraft but even then these are mostly older aircraft that will later be used as Kamikaze's, not what you want to put a grossly inexperienced pilot into and then say "Go fight a Hellcat or Corsair." Because honestly it'll just be quicker to shoot the pilot there and then. At least it'll save you the fuel.

3 - Fuel. Yamato's were THIRSTY (think the internet thirsting over Lady Dimitrescu from Resident Evil and ramp it up from there) ships, they guzzled fuel, and it was one of the reasons they were not used earlier, they saw a fuel tanker, and other battleships went CHUG! CHUG! CHUG! CHUG! and so they did. Now you're ramping up the fuel issues with a 3rd or god forbid a 4th Yamato. If you deploy all 4, you might have to drain the tanks of other big ships, meaning they can't take part, and even then, its probably not going to be enough. You might have to drain the tanks of both Nagato's to get one of them fueled up, so then the point of having both is gone. Do you drain the fuel of the Ise conversions? Then your deception and decoy force is less tempting? Taking away fuel from the Fuso and Yamashiro? I'm sure Admiral Nishamura would love that if he had to only make that attack with the Mogami.
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Now I'm imagining Nishimura's face when he's told he only has Mogami and four destroyers...

NGL, it's making me laugh. A lot. On a serious note, though, the fuel issue is a crippling problem and means that we can't get many ships to the battle in the first place.

How do we solve Yamato's drinking problem, then?
 

steamboy

With the conversion of the Ise's they didn't really use that much steel. They built up the sides sure. but the flight deck was a massive slab of concrete with wood on top of it, it wasn't steel.
 

RamscoopRaider

Donor
Kantai Kessen said:
I think the IJN's decision to build so many Unryus was foolish, and they'd have been better off with the resources they put in with three more Taihos. Is that possible?
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No, or rather they could have put the resources into 3 Taiho's instead of 6 Unryu's, but that means 3 carriers too late to do anything, rather than 1 available for Leyte in some form, 2 too late to do anything and 3 incomplete. Simply deciding to only built 3-4 Unryu's and the other resources to go to DD's and auxiliaries (tankers) would be better
Kantai Kessen said:
For many good reasons. Whoever thought that was a good idea deserved to be shot. Waste of two perfectly good battleships.
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Part of the issue was that the rear turret on the Fuso's and Ise's could not be modified to increase elevation in the same way as the other turrets as that would require deepening the barbette, which could not be done, so the rear turret would be useless for long range engagements, plus Hyuga blew her #5 turret and it was quicker to remove than repair. So even prewar they were talking about removing at least the rear turret for aviation facilities
 
Kantai Kessen

Kantai Kessen

steamboy said:
This. Build smaller ships, call it Yamato.
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But that is totally out of line with the IJN's thinking at the time. They NEEDED a ship that could fight multiple contemporary enemies and come out on top with acceptable damage. Hence a 65,000 tonne behemoth with enough armour to withstand an asteroid strike.
 

NOMISYRRUC

Kantai Kessen said:
Now I'm imagining Nishimura's face when he's told he only has Mogami and four destroyers...
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Perhaps the Japanese should have simplified their plan - I know that plan and simple go together like flesh and sulphuric acid to a Japanese naval officer.

That is, concentrate the battleships into a single force and hope that sheer brute force will win the day. Said brute force would include up to 12 capital ships, plus more cruisers and destroyers.

AIUI Shima's force wasn't able to join up with Nishimura. Therefore, Shima's 3 cruisers and 7 destroyers should be given to Ozawa to strengthen the screen of the carrier decoy force.
 
Kantai Kessen

Kantai Kessen

RamscoopRaider said:
No, or rather they could have put the resources into 3 Taiho's instead of 6 Unryu's, but that means 3 carriers too late to do anything, rather than 1 available for Leyte in some form, 2 too late to do anything and 3 incomplete. Simply deciding to only built 3-4 Unryu's and the other resources to go to DD's and auxiliaries (tankers) would be better

Part of the issue was that the rear turret on the Fuso's and Ise's could not be modified to increase elevation in the same way as the other turrets as that would require deepening the barbette, which could not be done, so the rear turret would be useless for long range engagements, plus Hyuga blew her #5 turret and it was quicker to remove than repair. So even prewar they were talking about removing at least the rear turret for aviation facilities
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If DDs, then please more Akitzuki and Matsu-class ships. PLEASE - the IJN needs a superb AA destroyer and a good escort ship anyway.

Tankers would be great, but the Matsus in particular will be needed to stop those being eaten by submarines.
 
Kantai Kessen

Kantai Kessen

NOMISYRRUC said:
Perhaps the Japanese should have simplified their plan - I know that plan and simple go together like flesh and sulphuric acid to a Japanese naval officer.

That is, concentrate the battleships into a single force and hope that sheer brute force will win the day. Said brute force would include up to 12 capital ships, plus more cruisers and destroyers.

AIUI Shima's force wasn't able to join up with Nishimura. Therefore, Shima's 3 cruisers and 7 destroyers should be given to Ozawa to strengthen the screen of the carrier decoy force.
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I'd rather send Shima's ships with Kurita: 2 CAs, a CL and 7 DDs would help a lot.

Mogami can go with Ozawa, seeing as she's basically an aviation vessel anyway by this point.

So this gives Centre Force (assuming no crap Ise conversion):
BB: Yamato, Musashi, Shinano, Nagato, Mutsu, Ise, Hyuga, Fuso, Yamashiro, Kongo, Haruna
CA: Tone, Chikuma, Suzuya, Kumano, Takao, Atago, Maya, Chokai, Myoko, Nachi, Haguro, Ashigara
CL: Noshiro, Yahagi, Abukuma
+ 23 DDs (we're using the eight assigned to Southern Force historically)

Can we still add carriers?
 
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ShySusan

Gone Fishin'
Kantai Kessen said:
But that is totally out of line with the IJN's thinking at the time. They NEEDED a ship that could fight multiple contemporary enemies and come out on top with acceptable damage. Hence a 65,000 tonne behemoth with enough armour to withstand an asteroid strike.
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Did they really? To my knowledge, neither Yamato nor Musashi ever even saw an American battleship, let alone fired on one. Even if we agree that Japan needed better ships to counter higher American and British numbers, they should have realized that you can't get everything you want. Japan knew they would have restricted supplies of oil during any war with the US. And that's even assuming they manage to capture the DEI oil fields and refineries intact. Basic common sense should have told them that a very good ship that's usable is far better than an excellent ship that can't leave port because it doesn't have enough fuel.
 
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Kantai Kessen

Kantai Kessen

ShySusan said:
Did they really? To my knowledge, neither Yamato nor Musashi ever even saw an American battleship, let alone fired on one. Even if we agree that Japan needed better ships to counter higher American and British numbers, they should have realized that you can't get everything you want. Japan knew they would have restricted supplies of oil during any war with the US. And that's even assuming they manage to captor the DEI oil fields and refineries intact. Basic common sense should have told them that a very good ship that's usable is far better than an excellent ship that can't leave port because it doesn't have enough fuel.
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Sometimes asking common sense from the IJN is a bit beyond possible... Alas.

Hang on; the Japanese are friends with the Germans. Now I'm thinking:

Diesel Yamato?
 
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