ORIGINAL: Shark7
Different references most likely. I took all the information and plugged it into Springsharp to come up with this.
Durability and manuevre...I've yet to figure out the true formula on these, so I took an educated guess. Probably undervalued the durability. Manuevre I based partly on the fact that Montana would have been huge.
My reference indicated 4 floatplanes.
Ammo, Typo on the main gun rounds, should have been 10 actually. I rated her for 100 rounds per gun, which seems pretty standard for US types. Iowa was also 100 rounds per gun IIRC.
I used;
http://www.history.navy.mil/photos/usnshtp/bb/bb67.htm
http://www.hazegray.org/navhist/battleships/us_wwii.htm
http://web.archive.org/web/200708211125 ... hip-US.htm
as my main sources for data on the Montana class.
Im curious what yours is, if it suggests 4 floatplanes and 5in/38s - these were phased out of the design after Scheme 3.
Its well known that SpringSharp dosent handle the USNs high efficiency engines well - try modelling an Iowa and youll see the bunkerage is also way off. Its a fair (and I use the term loosely) approximation for IJN and RN ships however.
You should remember that SpringSharp is just a 'rough sketch' of a ship proposal, and should be used as part of a whole rather than relied on exclusively for creating a design. Empirical data as I used in working out a reasonable bunkerage is one such other method.
For Durabilities, the formula I use is
Dur = S * ( (SD/250) - (SD/250)*(1950-YL)*0.005)
SD is Standard Displacement
YL is Year Launched
S is a scaling factor representing design factors and design philosophy - this is around 1.25-1.30 for BBs, and normally about 2-3 hundredths less for IJN ships than western ones.
Additionally, all tonnage over 35,000 is halved for displacement calculations, and everything above 70,000 is quartered. So 65,000tons is entered as 50,000tons. (65k - 35k = 30k, 30k / 2 = 15k, 35k + 15k = 50k)
I also use an adaption of this to work out approximate changes due to refits/rebuilds, based on a "percentage affected" notion.
I generally end up within 5 points of stock ships when all is said and done, with the exception of the USN Treaty and Fast BBs which are in my opinion underrated in stock. (SoDak durability is 152...this is less than Nagato! I used 178 for SoDak, with Iowa at 202.)
Also, NavWeaps says 130 rpg for Iowa class. I'd guess at ~110 rpg for Montana.