From: The Divided Nations of Earth
Some comments on the new stuff;
Battleships and building schedules
As was mentioned before, spreading out the US builds might make more sense. Personally I would suggest cutting the South Dakota and Lexington classes to 4 ships each, and then build a new class of battleship or battlecruiser in the late 20s or early 30s, based upon one of the many design proposals from the time.
Cruisers and guns
I like the cruiser lineups, apart from the fact that the gun calibers are all over the place. Every nation seems to jump back and forth between 8", 10" and occasionally larger weapons, with no regard for standardization. Likewise, the 'heavy' light cruisers like the Brooklyn and Mogami probably would not have taken shape in this reality, being something of a product of the treaties (though admittedly one that turned out rather well as a nightfighter and bombardment platform). Lastly, the Italian Zara class with a mixed main battery seems like something more appropriate for 1902 than 1942.
I would suggest redoing the cruisers somewhat; in a reality like the one you propose I can see 3 'sizes' of cruisers emerge;
'Escort' cruisers, around the 4000-6000ton mark, with 5-7in guns; intended for convoy duty, warding off destroyers and later in the war maybe AA work.
'Light' cruisers around the 10000ton mark, with 7-10in guns, intended as cruiser hunters, and leaders of smaller cruiser groups.
'Heavy' cruisers around the 14-18000ton mark, with 10-12in guns, intended as general purpose vessels also capable of taking part in the battleline.
Obviously, each nation will build things suited to their requirements, and put their own 'spin' on these categories, such as German raiders, etc.
So for example, with regards to Japan, I might suggest something like this, beginning with Furutaka;
4x CL Furutaka (4x2 8in) ~9500t / 32knts
4x CL Myoko (4x2 9.2in) ~10500t / 34knts
2x CL Chokai (3x3 9.2in) ~12000t / 34knts
2x CA Maya (2x2 12.2in) ~14500t / 34knts
4x CE Agano (4x2 6in) ~6000t / 29knts
4x CL Mogami (3x3 9.2in) ~12000t / 35knts
4x CA Tone (2x2 12.2in) ~15000t / 34knts
2x CE Oyodo (3x3 6in) ~6500t / 30knts
2x CA Kasuga (3x2 12.2in) ~16500t / 34knts
The same applies here, though you're likely to see more variation in gun caliber simply because of the easier logistics. Most likely national design philosophy will determine the majority of things here. However, some general categories I can see arising;
Destroyer 'Leaders', as a replacement to that role being fulfilled by CLs in certain navies historically. Larger than regular DDs by some 25-50% (so 2500-3000t for a 2000t flotilla), possibly with larger caliber weapons or more of them (latter makes more sense to me) and/or more torpedoes.
'Large' Destroyers, built mainly for anti-surface work; high speed (35knts+), heavy gun or torpedo batteries, probably in the 2500-3500t range (think Shimakaze or Sumner historically). Possibly later designs split into torpedo based ones for ASuW, and gun based with DP guns into an AA escort role.
'Fleet' Destroyers, built as an all purpose platform with good range; moderate-high speed (~32knts), decent weaponry possibly with a focus on guns over torpedoes, tonnage 1500-2500t. Probably the first type to mount DP weapons.
'Escort' Destroyers, built for anti-sub and (later) anti-air work; moderate speed (~30knts), mixed weaponry though possibly lighter on the torpedoes. Tonnage around 1000-2000t.
In addition, specialist designs like lighter torpedo destroyers (something of a souped up TB), dedicated ASW escorts, etc. might appear depending on how development goes. Once again, national preferences are a big influence here.
Designs and numbers
Lastly, if you would like any help with estimates/design stuff for any of these, I can help out (from stuff like 'if it has these guns, this protection and this speed, then how heavy is it gonna be' to 'if it needs these guns and this speed but cant exceed x tonnage, how much armour can you put on?'). Let me know here or in PM, I can post examples if needed.
Hmmm. Digging back in my own thread a little I had forgotten about this excellent post. Think I'll do a little dwelling on this and try to come up with some ideas.