Submarines...
Just using LNT models, and tweaking launch platform tonnage about 25%
The IJN was limited to 52,700 tons (26 -52 boats new construction) and wanted 78,000 tons (39-78) boats new construction)
The upper limits set at 78,000 would make things "difficult" for the USN and RN, but would have probably have worked in the Wally interests better.
British efforts...
As for that 600 ton SD limit and below for unlimited subs? Naughty, naughty.
Note the casualty rate for the British boats? about 45% lost of units built. (24 of them.)
Japanese submarine construction...
-195 ocean going boats in a bewildering series of types. (Most of them slaughtered.)
-700 coastal brown water types of less than 50 tons displacement. (Most of them never used.)
US submarine follies.
~100 boats as of Pearl Harbor and 240 war builds. That is correct... 240 war-builds.
Now suppose Congress gets off its duff and allows the O, R, and S boats (13 year replacement rule in the treaties) to be replaced by Mackerels (~600 ton SD treaty cheaters)? And Uncle gets to build to 78.000 tons with the other boats? (39-78 boats). 96 + 78 = 174 boats which is 74 more boats than the 7 December listed as available. What happens as of that December month of 1941 if there are 100 boats in the PACFLT instead of the 60 as OOBed??
The actual results were 0.2 ships sunk per sortie (60 boats available.) =12 ships sunk that month.
40 more boats = 20 ships sunk. Assuming the crews remain trained wrong, the torpedoes do not work and Withers and English and W.E. Doyle remain the braindead idiots they were, not much changes. Need to solve the weapons, retrain the crews and send Withers and Doyle to the Aleutians to count penguins. (I know there are no penguins in the Aleutians, but ride with the metaphor!)