Re: And the thrid ship
Ahem, it is Shinano, not Shimano.
It is true that details were a closely guarded secret at the time, but with the passage of history all has become known in intricate detail.
See "Design and Construction of the Battleships Yamato and Musashi", by Kitaro Matumoto. Anyone who didn't buy this massive painstaking work when it came out in 1961 is not a serious historian. The main text is Japanese, but there is an English table of contents and appendix with copious tables and diagrams. From this we know such details as:
The exact dimensions of course[*]
details of 24 progressive designs leading to the final design
For secrecy the gun was officially termed Type 94 40cm, 45 caliber - actual bore was 46cm
Weights: gunnery, 11,802; armor, 23,500 tonns
The exact number of watertight compartments (1147)
The side armor being manufactured in 88.5 ton segments, 5.9x3.6m x410mm
The engine room floor area was 640 square metres
Superheated steam at 25 kg/mm^2 and 325 C from 12 boilers
[*] length overall, 263m; waterline, 253m; between perpendiculars, 244.0m
mean draft at full load, 10.86m
prismatic coefficient, 0.612
tactical turning diameter, 640m (heel 9 degrees)
period of roll 17.5 seconds
metacentric height at trial conditions, 2.88m
Mr. Matumoto defied an official order to destroy all documentation, saving voluminous notebooks.