London Naval Treaties have larger limits

Moffett argued those %s and he WON... fortunately. The USN negotiators at the LNC 1930 were not as good, but they still got the State Department fools to cap the cruisers to handicap IJN fleet command ship slots, thereby surface action groups available, and hobble IJN aviation at sea with weak fleet screens for CTFs, (Fleet Problem XIV lesson learned), thereby.
I don't see how not sure that being allowed 70% rather than 60% of American's strength in capital ships by the WNT would have helped them.

OTH because the Japanese were Lizzy Drippings when it came to telling the truth about their warship's displacements makes a lot of difference in the carrier battles of 1942.

This is because it increases the Japanese quota from 81,000 tons to 94,000 tons. IOTL the 2 capital ship conversions consumed 53,800 tons and the Japanese used the 27,200 tons that were left to build Ryujo, Soryu and Hiryu, which the Japanese said displaced 7,100 tons, 10,050 tons and 10,050 tons respectively, which were fibs of pavarotic proportions.

70% of 135,000 tons is 94,500 tons. That increases the tonnage available after the capital ship conversions were completed to 40,700 tons, which they would use to build 4 ships with an official displacement of 10,175 tons. However, the first pair, built instead of Ruyjo would be Soryu class with a real displacement of 15,900 tons and the the second pair built instead of the OTL Soryu and Hiryu would be built to the Hiryu design and displace 17,300 tons.

If that was the only change between OTL and TTL between 1922 and 1940 it's likely that the 2 ships built instead of Ryujo are part of the Kido at the end of 1941 and take part in the raid on Pearl Harbour, the attack on Darwin and the Indian Ocean raid. I think they'll be refitting during the Coral Sea, but both ships will be at Midway and add another 108-126 aircraft to the Japanese air strength. I'll be prudent and say that Akagi, Kaga and Soryu are still sunk but the other 3 Japanese carriers and most of their aircrew survive. Yorktown is still sunk but the other 3 ships survive. The Japanese probably win the Battles of the Eastern Solomons and Santa Cruz.

However, before anyone points out the obvious. I know that the Americans would have out built them by 1944 and it doesn't change the outcome of the war. However, they might not suffer such heavy losses at the Philippine Sea if the Hiryu, ALT-Ryujo and the 4th ship survive to take part in it. If they survive that I doubt that they will be at Leyte Gulf, because there won't be the fuel or enough trained aircrew. Though having written that, they might take the place of Zuiho, Chitose and Chiyoda.
 
Last edited:
As fast as the Japanese ramped up radar from nothing to about 2x the British effort in 1940, and put that into their calendar year 1943 context (RTL). Ranp up 1944 island fortification to 1943 calendar year using @NOMISYRRUC thesis points; such as to an improved Japanese merchant fleet (9 million tonnes instead of 7 million tonnes DWT). And suggest that the Raiden and other Japanese interceptors come a year earlier, because now the Japanese government can fund the work just pre WWII. The B-29s will have a SERIOUS as in suicidally motivated and directed air defense to fight with well-motivated Japanese pilots willing to die as ramming agents to stop any American bomber. The Americans will be atomic bombing their way from Peleliu forward. They have to get within B-29 range. I could even see a bypass the Philippine Islands and nuke Taiwan just to get bombers in range outcome; as a function of the naval geography and the unfolding campaign. That is about 30 bombs just to get that far.

2 years is if everything goes right for the Americans.
The extra IJN ships in 1941 won't matter in the end, once the USN submarines mine intra-Japan shipping lanes.
 
You have to spend marines to get into bomber range. MEN. That is why atomic bombs on every damned island assaulted, and that is why the campaign changes. Ships deliver marines to islands and the marines dig those tough Japanese farm-boys out of one atom bombed Iwo Jima after another. A richer Japan means more farm boys, more caves, and more concreted in machine gun and mortar emplacements.

It is a very narrow window of time (about 18 months for the US in 1943 and 1944) that "easy" amphibious assaults' are possible.
How soon after the atomic bombing would the invasion go in? I am thinking atomic bombs, small islands, and amphibious assaults are a bad combination for all involved. For the Americans, probably more post-war than during the war. Establishing bases on irradiated islands adds to the long-term adverse effects. Short-term, for winning the war, okay. It will be a higher butcher's bill than OTL regardless.
 
With the weak Japan the Americans faced in our RTL, each landing became progressively harder and harder to accomplish and each island delousing took longer and longer as the Japanese decided on a defense in depth and a casualty infliction attrition application to exhaust the American will to fight. All they needed were those farm-boys and some artillery and machine guns and it worked! Now with a 50% stronger Japan, figure the added time needed and expected casualty increases the Americans will face. The ETO troops who had a bellyful of Germans who were being shipped from Europe to the Philippine Islands and thence to smoking ruined Okinawa to participate in the Kanto Kombat that was expected denouement for DOWNFALL were not eager to march on Tokyo. They read the newspapers and being veterans themselves, had a rather realistic assessment of what Olympic and Coronet could cost. Bombs can get you ashore, but the dug in farm-boys still have to be routed out on that runway real estate needed to project airpower forward.

That is the whole point.
It's not just ships and planes , it's tanks, artillery and virtually the entire Western Front moving to the Pacific Front. Also you don't need the entirety of the various islands. All you need is enough land to build airstrips with a small defensive zone around them . The islands themselves are near worthless, for the most part. All you need them for is airbases.
 
I don't see how not sure that being allowed 70% rather than 60% of American's strength in capital ships by the WNT would have helped them.
The cruisers are what matter. Battleship combat in the Pacific War is a rare (4 times) event in the conflict, with the Americans either usually enjoying new against old, and better against worse admirals, and surprisingly (And always MISSED by relevant so called experts.) guns and anti-ship ammunition in the surface action to be immediately followed or accompanied by close air support with Samar and the Guadalcanal battles showing what combined arms means to a "gun-club" admiral who is all battleships', cruisers', destroyers' guns and torpedoes, versus an enemy who uses an air force to support his own surface forces. As the kahunas say; "Wipeout."

OTH because the Japanese were Lizzy Drippings when it came to telling the truth about their warship's displacements makes a lot of difference in the carrier battles of 1942.
That sword cuts both ways.

This is because it increases the Japanese quota from 81,000 tons to 94,000 tons. IOTL the 2 capital ship conversions consumed 53,800 tons and the Japanese used the 27,200 tons that were left to build Ryujo, Soryu and Hiryu, which the Japanese said displaced 7,100 tons, 10,050 tons and 10,050 tons respectively, which were fibs of pavarotic proportions.
-To be fair to the Japanese, they "tried" to meet their declared "treaty" tonnages, but because of bungled ship-wrighting, they had to go back and bulge and do other things to fix the bungled top-heavy float bubbles in their named construction. The actual cheating comes in at Shōkaku and Zuikaku after the LNT walkout. (and the shadow program ships.)

70% of 135,000 tons is 94,500 tons. That increases the tonnage available after the capital ship conversions were completed to 40,700 tons, which they would use to build 4 ships with an official displacement of 10,175 tons. However, the first pair, built instead of Ruyjo would be Soryu class with a real displacement of 15,900 tons and the the second pair built instead of the OTL Soryu and Hiryu would be built to the Hiryu design and displace 18,500 tons.
And were EASY to mission kill and burn down because the designs were "poor" as far as gasoline stowage, elevators, rudder and screw placement, and flammability were concerned. If the tonnage is not used well, then the IJN will find that those 4 bird-farms built to the 15,000 tonne Hiryu standard still are one bomb write-offs. This will matter with the Midway discussion in a moment.

If that was the only change between OTL and TTL between 1922 and 1940 it's likely that the 2 ships built instead of Ryujo are part of the Kido at the end of 1941 and take part in the raid on Pearl Harbour, the attack on Darwin and the Indian Ocean raid. I think they'll be refitting during the Coral Sea, but both ships will be at Midway and add another 108-126 aircraft to the Japanese air strength. I'll be prudent and say that Akagi, Kaga and Soryu are still sunk but the other 3 Japanese carriers and most of their aircrew survive. Yorktown is still sunk but the other 3 ships survive. The Japanese probably win the Battles of the Eastern Solomons and Santa Cruz.
It is likely that those 2 ships built, means one old flattop will be a training carrier to replace Hosho and the other bird farm goes north with Hosagaya to raid Dutch Harbor. So instead of Kaga, tough to burn down, and Soryu, easy to mission kill, we get 2 or 3 Hiryus and Soryu and Akagi sails with Hosagaya (old and slow). Actually that works to Spruance's favor and even Nautilus gets her chance, because she misjudged her target's speed *(a couple of fish ran ahead of Kaga as she limped ahead on fire.) and BOOM.

However, before anyone points out the obvious. I know that the Americans would have out built them by 1944 and it doesn't change the outcome of the war. However, they might not such heavy losses at the Philippine Sea if the Hiryu, ALT-Ryujo and the 4th ship survive to take part in it. If they survive that I doubt that they will be at Leyte Gulf, because there won't be the fuel or enough trained aircrew. Though having written that, they might take the place of Zuiho, Chitose and Chioyoda.
Now what do the Americans do with their carrier tonnage? Because they will use the 10,140 tonne exception in part to make up for the 70% the IJN have earned. This is a good question. But, let us do the BC subtraction thing.

135.000 tons SD
- 66,000 tons SD
...69,000 tons SD

3 x 20,000 ton SD carriers and 1 x 9,000 ton "aviation ship" ? Suppose the Americans declare their battlecruiser conversions come in at 27,000 tons? They claim they stripped out all the hull armor and are entitled to 11,000 tons SD + the 69,000 tons?


135.000 tons SD
- 54,000 tons SD
...80,000 tons SD

Ranger, Wasp, Yorktown and Enterprise are all full blooded attack carriers. Things get "sticky" as that adds about 100 aircraft to the USN seaborne aviation. Then add Hornet. So 7 against 8 theoretically in 1941. No difference at all in the actual results except that Wasp is tougher and the IJN ships, Kaga, Akagi, Soryu, Hiryu, Ryujo all still will die by fire. Then you get those 10,000 "Northampton" aviation depot and tender ships as the 10,140 tonne WNT clause exceptions. 2 x those =a Yorktown. Let us be parsimonious and say 4 get built and assigned to LANTFLT in place of Ranger and Wasp.

Coral Sea is 4 against 3 and Shōkaku does not make it, but Lexington does. Yorktown is still hit.

Midway, it is 5 against 5. Wasp with Sherman is there instead of the incompetent Mitscher and Hornet. Lexington is there with Yorktown, Fitch hands fleet air ops instead of Fletcher and then Spruance by the seat of his pants. Who jumps whom? Based on Coral Sea and with Nagumo and crew instead of the far better Hara and staff? 70 torpedo planes instead of 41? A decent fighter escort with the low boys now instead of Slim Pickens and the scrubs off Saratoga? Kido Butai's chances? ZERO. Hiryu will not survive the first Alpha. Zuikaku will be lucky if she floats home alive. Kongo will be lucky if she makes it home alive. Eastern Solomons becomes a cake walk. There will be no Santa Cruz. there might not even be a Savo Island or if it is, daylight finds Fletcher all over Mikawa.

The extra IJN ships in 1941 won't matter in the end, once the USN submarines mine intra-Japan shipping lanes.
US mines have the same magnetic influence feature problem as their torpedoes.
How soon after the atomic bombing would the invasion go in? I am thinking atomic bombs, small islands, and amphibious assaults are a bad combination for all involved. For the Americans, probably more post-war than during the war. Establishing bases on irradiated islands adds to the long-term adverse effects. Short-term, for winning the war, okay. It will be a higher butcher's bill than OTL regardless.
Truk gets a bomb right away ASAP. Rabaul earns one. I suspect that it will be more of a case of delousing and then land on the nearest flat island with no Japanese farm-boys on it and build an airstrip and then use any convenient breakwater atoll near to it to be a fleet anchorage. More Kwajalein and Ulithi than Peleliu. Still have to clean out the irradiated farm boys because some islands HAVE to be taken. Saipan and Tinian would be examples. Iwo Jima as well is an example. Once the close in for the kill happens, I suspect that bombing the home islands would be part of the anti-kamikaze campaign to protect the fleet. Okinawa would get the treatment; half and half. need some of the island for basing. It would make the Americans = to the Germans as WWII war criminals once the judgements of history roll in.

It's not just ships and planes , it's tanks, artillery and virtually the entire Western Front moving to the Pacific Front. Also you don't need the entirety of the various islands. All you need is enough land to build airstrips with a small defensive zone around them . The islands themselves are near worthless, for the most part. All you need them for is airbases.
See my above comments, JR. The thing is, the Japanese are not stupid in the op-art or when they go defense. They learn fast. They adapt and are clever in their limited choices. You see this happen in how they fight, how they plan and how they adapt. US casualties at sea and on land go way up in the last year of the war.
 
Last edited:
Wait a moment, so how will the Mk 14's deficiencies not be remedied by 1944 (as they were in OTL), short of invoking an ASB or two?
It only gets fixed in the mines when the torpedo fixers (Mommsen) gets the light-bulb and realize that the magnetic mines have the same kind of fusing as the torpedoes (Sept. 1943). It will be fixed, but about this time, the air farce has figured out how to make a wake pressure wave set off a mine. Flip a coin. 1945, the Japanese are SCREWWWWWED.
 
And were EASY to mission kill and burn down because the designs were "poor" as far as gasoline stowage, elevators, rudder and screw placement, and flammability were concerned. If the tonnage is not used well, then the IJN will find that those 4 bird-farms built to the 15,000 tonne Hiryu standard still are one bomb write-offs. This will matter with the Midway discussion in a moment.
They have to be hit first.
 
Last edited:
Now what do the Americans do with their carrier tonnage? Because they will use the 10,140 tonne exception in part to make up for the 70% the IJN have earned. This is a good question.
I doubt that very much. If only because of this part of the 1930 London Naval Treaty.
Article 4​

1. No aircraft carrier of 10,000 tons (10,160 metric tons) or less standard displacement mounting a gun above 6.1 inch (155 mm) calibre shall be acquired by or constructed by or for any of the High Contracting Parties.

2. As from the coming into force of the present Treaty in respect of all the High Contracting Parties, no aircraft carrier of 10,000 tons (10,160 metric tons) or less standard displacement mounting a gun above 6.1 inch (155 mm) calibre shall be constructed within the jurisdiction of any of the High Contracting Parties.
 
I doubt that very much. If only because of this part of the 1930 London Naval Treaty.
Article 4 is very interesting...

1. No aircraft carrier of 10,000 tons (10,160 metric tons) or less standard displacement mounting a gun above 6.1 inch (155 mm) calibre shall be acquired by or constructed by or for any of the High Contracting Parties.

2. As from the coming into force of the present Treaty in respect of all the High Contracting Parties, no aircraft carrier of 10,000 tons (10,160 metric tons) or less standard displacement mounting a gun above 6.1 inch (155 mm) calibre shall be constructed within the jurisdiction of any of the High Contracting Parties.
What about a flattop mounting 12.7cm/L38s and guns of bore diameter smaller? That would be something on the order of an Independence.

They have to be hit them first.
That will not be a problem. As it was not a problem. Japanese CAP was the worst.
 
Last edited:
It is likely that those 2 ships built, means one old flattop will be a training carrier to replace Hosho and the other bird farm goes north with Hosagaya to raid Dutch Harbor. So instead of Kaga, tough to burn down, and Soryu, easy to mission kill, we get 2 or 3 Hiryus and Soryu and Akagi sails with Hosagaya (old and slow). Actually that works to Spruance's favor and even Nautilus gets her chance, because she misjudged her target's speed *(a couple of fish ran ahead of Kaga as she limped ahead on fire.) and BOOM.
To paraphrase Robin, "Wholly incomprehensible Batman!"

I think that you are saying that Kaga replaces Hosho as training carrier. Which if correct, I disagree. The Japanese won't have reached their tonnage quota before the end of 1936 and will be able to keep Hosho.

ALT-Ryujo may still go north with Junyo. However, Nagumo will still have the 4 carriers of OTL plus the "extra carrier". Her fighters might be able to interfere with the dive bombers and reduce the number of bombs that hit the carriers. If they don't there are still twice as many fighters, i.e. Hiryu and the "extra carrier" to intercept subsequent American attacks.

I could be less prudent and say that ALT-Ryujo and her TTL sister didn't take part in the Indian Ocean raid and joined Shokaku and Zuikaku at the Coral Sea. None of the Japanese fleet carriers were damaged and both American carriers were sunk. Nagumo sails for Midway with the 4 CV of OTL plus Shokaku and Zuikaku. ALT-Ryujo and the "4th Carrier" are assigned to the attack on Dutch Harbour. If Nimitz decides to sent Enterprise and Hornet to defend Midway they sink a maximum of 2 Japanese carriers.
 
Last edited:
Now what do the Americans do with their carrier tonnage? Because they will use the 10,140 tonne exception in part to make up for the 70% the IJN have earned. This is a good question. But, let us do the BC subtraction thing.

135.000 tons SD
- 66,000 tons SD
...69,000 tons SD

3 x 20,000 ton SD carriers and 1 x 9,000 ton "aviation ship" ? Suppose the Americans declare their battlecruiser conversions come in at 27,000 tons? They claim they stripped out all the hull armor and are entitled to 11,000 tons SD + the 69,000 tons?

135.000 tons SD
- 54,000 tons SD
...80,000 tons SD
...81,000 tons SD

Ranger, Wasp, Yorktown and Enterprise are all full blooded attack carriers. Things get "sticky" as that adds about 100 aircraft to the USN seaborne aviation. Then add Hornet. So 7 against 8 theoretically in 1941. No difference at all in the actual results except that Wasp is tougher and the IJN ships, Kaga, Akagi, Soryu, Hiryu, Ryujo all still will die by fire. Then you get those 10,000 "Northampton" aviation depot and tender ships as the 10,140 tonne WNT clause exceptions. 2 x those =a Yorktown. Let us be parsimonious and say 4 get built and assigned to LANTFLT in place of Ranger and Wasp.
I'm continuing to find you prose style hard to interpret.

As I already wrote the 10,000 ton loophole was closed by the 1930 Treaty.

I'm not convinced that the Americans will pretend that Lexington and Saratoga displace 27,000 tons. However, if they did...

IOTL they initially wanted to get the maximum number of flight decks out of the remaining 69,000 tons and went for five 13,800 ton ships. However, they crammed too many aircraft into Ranger and decided to build a pair of 20,000 ton ships (Yorktown and Enterprise) and another small carrier (Wasp).

ITTL the Americans will want to build six 13,500 ton carriers. The ALT-Ranger will be even worse than the OTL-Ranger.

This leaves them with 67,500 tons, enough for three 22,500 ton ships or four 16,875 ton ships. I think the latter is too small a displacement to produce a satisfactory ship, so they will use the remainder of the tonnage quota to build three 22,500 ton ships in place of the OTL Yorktown, Enterprise and Wasp. Hornet is probably built to this design as well.
 
To paraphrase Robin, "Wholly incomprehensible Batman!"
Very comprehensible. Just play musical aircraft carriers.

Battle of Midway OOB.

Since Hōshō is with the main body, she slows Yamamoto down. Figure she is left behind and is replaced by Kaga. or do what the IJN did RTL and leave her where she is.

Even if the IJN builds to the Hiyo standard and Ryūjō and the Jun'yō come in at the 24,000 tonnes that they did, and managed to attain speeds and plane complements that they swap places with Kaga and Akagi, the Japanese do not get any more hulls than they do off Midway Island. Their tonnage is eaten up and they still screw up their op-plan.

Based on the history, Hiyo was a burn down at Philippine Sea. She was scuttled when the traditional vapors in the elevator aerosol bomb went off and did her like Taiho, Hiryu and Soryu. Jun'yō is a one hit wonder.

As I count up hulls and tonnages and outcomes, Nagumo probably cannot show up at Midway with more than 4 flattops, because the IJN had time and pilots to put Zuikaku into service RTL, but chose not to do so when they clearly could.
So... now 5 versus 4 and it is even worse for Nagumo.

I think that you are saying that Kaga replaces Hosho as training carrier. Which if correct, I disagree. The Japanese won't have reached their tonnage quota before the end of 1936 and will be able to.
I have covered this.(^^^)
ALT-Ryujo may still go north with Junyo. However, Nagumo will still have the 4 carriers of OTL plus the "extra carrier". Her fighters might be able to interfere with the dive bombers and reduce the number of bombs that hit the carriers. If the don't there are still twice as many fighters, i.e. Hiryu and the "extra carrier" to intercept subsequent American attacks.
I have covered this.(^^^) Nothing says Zuikaku should not have shown up. She did not for doctrinal reasons. Stupid is as stupid does. I cannot assume a different behavior.

And I could be less prudent and say that ALT-Ryujo didn't take part in the Indian Ocean raid and joined Shokaku and Zuikaku at the Coral Sea. None of the Japanese fleet carriers were damaged and both American carriers were sunk. Nagumo sails for Midway with the 4 CV of OTL plus Shokaku and Zuikaku. ALT-Ryujo and the "4th Carrier" are assigned to the attack on Dutch Harbour. If Nimitz decides to sent Enterprise and Hornet to defend Midway they sink a maximum of 2 Japanese carriers.
Takeo "Braindead" Takeo was lucky to get out alive. Coral Sea continued the amazing IJN luck that allowed them to roll 7s since Pearl Harbor.
I'm continuing to find you prose style hard to interpret.
Let me clear it up with some real history.

As I already wrote the 10,000 ton loophole was closed by the 1930 Treaty.
Based on how the USN sea-lawyered their BB rebuilds and the Northamptons, I'm gonna say that they will get away with an aviation depot ship excuse and make through deck Independence type tender ships stick.

I'm not convinced that the Americans will pretend that Lexington and Saratoga displace 27,000 tons. However, if they did...
They claimed 33,000 tons and those fat bird farms were closer to 40,000 tons. What's another 6,000 tonnes when the whopper is already 6,700 tons not true? Also the ships could be claimed as "experiments" as the "Curiosities" were.
IOTL they initially wanted to get the maximum number of flight decks out of the remaining 69,000 tons and went for five 13,800 ton ships. However, they crammed too many aircraft into Ranger and decided to build a pair of 20,000 ton ships (Yorktown and Enterprise) and another small carrier (Wasp).
ITTL the Americans will want to build six 13,500 ton carriers. The ALT-Ranger will be even worse than the OTL-Ranger.
Ranger was 15,000 tons SD. 1,200 tons over design, so...

Also it did not stop her from LANTFLT operations that included Torch and operations in the North Sea. For a defective aircraft carrier she sure liked to raid German sea lanes.

This leaves them with 67,500 tons, enough for three 22,500 ton ships or four 16,875 ton ships. I think the latter is too small a displacement to produce a satisfactory ship, so they will use the remainder of the tonnage quota to build three 22,500 ton ships in place of the OTL Yorktown, Enterprise and Wasp. Hornet is probably built to this design as well.
Shrug. As long as Wasp is a Yorktown class, then the IJN is screwed earlier.
 
Last edited:
See my above comments, JR. The thing is, the Japanese are not stupid in the op-art or when they go defense. They learn fast. They adapt and are clever in their limited choices. You see this happen in how they fight, how they plan and how they adapt. US casualties at sea and on land go way up in the last year of the war.
Same thing can be said of Americans, Brits, French , Russians and pretty much anyone else you can name. The big difference is all those countries will be gunning for Japan and they have a hell of a lot more resources than Japan does. No way in hell does Japan last another two years.
 
Same thing can be said of Americans, Brits, French , Russians and pretty much anyone else you can name. The big difference is all those countries will be gunning for Japan and they have a hell of a lot more resources than Japan does. No way in hell does Japan last another two years.
Logistics takes time and the Pacific is a huge salt water desert. People forget that.
 
Some background information on cruiser requirements.

At the 1927 Geneva Conference the British worked out the cruiser requirements for themselves, the USA and Japan as follows:
70 British Empire (25 fleet and 45 trade).​
47 USA (25 fleet and 22 trade)​
21 Japan (15 fleet and 6 trade)​

The fleet cruiser requirement was 5 for every 3 battleships. The trade cruiser requirement was a formula using the length of the trade routes and the amount of shipping at sea in tons.

This was a problem because the United States wanted parity with the British Empire in all classes of warship and they didn't want as many cruisers as the British because the they had a much smaller merchant fleet to protect.

They were able to reach a compromise in 1930 because the USA wanted big cruisers to operate in the Pacific and the British wanted smaller cruisers which could be built in greater numbers. Therefore, they were given tonnage quotas that were about the same size, but the Americans were allowed to more large cruisers, while the British were allowed more small ships. However, the quotas the OTL Treaty gave both nations fewer cruisers than they wanted.
 
I don't see how not sure that being allowed 70% rather than 60% of American's strength in capital ships by the WNT would have helped them.
Now I've thought about it increasing the 5:5:3 ratio to 10:10:7 would increase Japan's tonnage quota from 315,000 tons to 367,500 tons.

The Japanese would want to complete Kaga and Tosa because their construction was well advanced and they wouldn't want to waste the money they had already spent on them. The TTL quota was large enough for the Japanese to keep these ships and the 10 capital ships of OTL.

Japanese Capital Ships 1922.png


The spellings are from the Washington Naval Treaty. The tonnages are the standard displacements from Jentschura, Jung and Mickel.

I appreciate that the Japanese now have four "post-Jutland" ships instead of 2. I also know that the British and Americans will want at lease one more "post-Jutland" ship leading to the Americans completing BB-47 Washington and the British building a third Nelson. I also know that the standard displacements of Kaga and Tosa are more than 35,000 tons.

IOTL the Japanese planned to complete the battle cruisers Akagi and Amagi as aircraft carriers. The latter was damaged beyond repair in the Tokyo earthquake and the battleship Kaga was completed instead because the other incomplete battlecruisers had been scrapped. Kaga isn't available ITTL. Therefore, Erstaz-Amagi will have to be a new ship rather than a conversion.

I think that they will wait until they have more experience from Hosho and Akagi before building them and by the time they are ready to design a new ship will have decided to build the maximum number of fit for purpose ships from the 67,600 tons that are available. That produces five ships of 13,500 tons or six ships of 11,250 tons, but these will be the official standard displacements, the actual standard displacements will be more than that. I think they will build five ships displacing 13,500 tons because it gives them a grand total of six aircraft carriers which can be organised into three divisions of two or two divisions of three.

The first ship will be built instead of the OTL Ryujo and have an official displacement of 13,500 tons instead of the OTL 7,100 tons. However, her actual displacement will be in the region of 17,500 tons (or 200 tons more than the OTL Hiryu) instead of 8,000 tons and be a much better ship because of it.

Four follow on ships were built under the First and Second Fleet Replenishment Programmes. Two will be built instead of the OTL Soryu and form a Soryu class. The other two will be built instead of the OTL Hiryu and form a Hiryu class. The ALT-Soryu class incorporated the lessons learned from the ALT-Ryujo and the ALT-Hiryu class incorporated the lessons learned from the ALT-Soryu class.

The four follow on ships had official standard displacements of 13,525 tons, but they all displaced more than 17,500 tons, which was slightly larger than the OTL Hiryu. The actual displacements were 30% larger than their official displacements. However, that isn't as bad as OTL because Soryu was nearly 60% larger than her official displacement and Hiryu was nearly 75% larger.

The five aircraft carriers built from Japan's OTL quota of 81,000 tons had a combined air group of 282 aircraft before Akagi and Kaga were rebuilt and 342 aircraft after their modernisation. The six aircraft carriers built from the TTL quota of 94,500 tons had a combined air group of 375 aircraft before Akagi was rebuilt and 405 afterwards.

If the Americans did lie about the displacements of Lexington and Saratoga in the fashion you have suggested the Japanese might make the same claim for Akagi. That won't result in them building a seventh ship out of their 94,500 tons. However, they would use the balance to increase the official displacement of the five bespoke ships and the real displacement will be 30% greater than that.
 
Alternative London Naval Treaty - No Capital Ship Conversions

The Americans and Japanese decide that converting capital ships is not a good way of using their tonnage quotas because British experience had already proved that a converted ship carries less aircraft than a new ship of the same displacement.

The Americans want as many aircraft carriers as possible and decide to build ten ships of 13,500 tons. A prototype is completed in 1927 using the money spent on converting Lexington and Saratoga. She actually displaces nearly 15,000 tons and in common with the OTL Ranger isn't fit for purpose because she was designed to carry the maximum number of aircraft at the expense of speed and protection.

They have 120,000 tons left, which they decide to use to build six 20,000 ton carriers. Two are built instead of the OTL Ranger, two are built instead of the OTL Yorktown and Enterprise, and two are built instead of the OTL Wasp. A seventh ship of the 20,000 ton type might be built in place of the OTL Hornet.

That gives them six front-line and one second-line aircraft carriers out of their 135,000 tons instead of the four first-line and two second-line ships of OTL.

Meanwhile, the Japanese also decided that they want the maximum number of ships from their TTL quota of 94,500 tons. They can have six 15,750 ton ships or eight 11,800 ton ships on paper, but they would really displace around 20,500 and 15,350 tons respectively. They decide upon the latter.

A pair of aircraft carriers with official displacements of 11,800 tons is built instead of the OTL Amagi and Kaga. They were satisfactory ships, because unlike the TTL American prototype of similar displacement they were designed to accommodate 54 aircraft instead of 72 and therefore had a better balance of armament, protection and speed.

However, instead of the original plan for six follow on ships of 11,800 tons (official) they decide to build 4 ships of 17,725 tons (official) but the real displacement was in the region of 23,000 tons. They could carry 81 aircraft instead of 54. Therefore, the total was still 324 aircraft because 6 x 54 = 324. Two ships were built at the time of the OTL Ryujo and two were built instead of the OTL Hiryu and Soryu.

This gives the Japanese four fleet and two light fleet carriers out of their TTL quota of 94,500 tons, instead of the four fleet and one light fleet carriers built from their OTL quota of 81,000 tons.
 
Some background information on cruiser requirements.

At the 1927 Geneva Conference the British worked out the cruiser requirements for themselves, the USA and Japan as follows:
70 British Empire (25 fleet and 45 trade).​
47 USA (25 fleet and 22 trade)​
21 Japan (15 fleet and 6 trade)​

The fleet cruiser requirement was 5 for every 3 battleships. The trade cruiser requirement was a formula using the length of the trade routes and the amount of shipping at sea in tons.

This was a problem because the United States wanted parity with the British Empire in all classes of warship and they didn't want as many cruisers as the British because the they had a much smaller merchant fleet to protect.

They were able to reach a compromise in 1930 because the USA wanted big cruisers to operate in the Pacific and the British wanted smaller cruisers which could be built in greater numbers. Therefore, they were given tonnage quotas that were about the same size, but the Americans were allowed to more large cruisers, while the British were allowed more small ships. However, the quotas the OTL Treaty gave both nations fewer cruisers than they wanted.
Now that is WEIRD. The British must have been stuck on Jutland at the time, because the Americans certainly did not see cruisers the same way the British did (presence and sea control as opposed to patrol.). Also, since the US trade routes to Asia and South America were every bit as long as the UKs, I find it "specious" that the British thought that trade protection depended on size of merchant marine as opposed to PRESENCE in area. If anything, if the USN could have had their way, their chronic cruiser shortage would have been remedied with more cruisers than the RN, not less. (about 75-80 minimum).

Large cruisers? That was a USN forced choice based on a lack of fleet oilers and trains. Experience with constant refueling in the middle of high speed operations in the SpanAm war and in WWI plus all the oil and av-gas guzzled in fleet problems also made large cruisers with big fuel bunkers kind of necessary.
 
Top