Montana Preliminary Designs BB65C

Th BB65C design was among the first series of designs of mid 1939 eventually leading to the Montana class. This series starting with A was essentially an enlarged South Dakota rather than a modified Iowa with A being basically a four turreted South Dakota, B having 6"/47 DP-AA guns and C utilising the quadruple turret scheme originally envisioned for the North Carolina Class but all of them were protected as the Iowa.

The baseline design had these characteristics:
Dimensions: 243,84 (wl) x 32,92 x 10,97m
Displacement: 43.800tons (standard)
Armour: 178mm deck and 307mm belt over machinery and magazines
Engines: 130.000shp General Electric Steam Turbines, 4 shafts
Speed: 51km/h (27,5knots)
Armaments:
3x4 16"/50 (406mm) Mark 7 Cannons,
10x2 5"/38 (127mm) Mark 12 Guns,
I've choosen the following AA suite:
16x4 40mm/56 Mark 1/2 AA Guns,
48x1 20mm/70 Mark 2 AA Guns

Table showing the various designs:
i.imgur.com/HJ6OPB2.png

C-5 utilises the turret layout of the British King George V class battleships of 2 quad turrets at the ends and a superfiring twin forward. While the hull, superstructure and AA layout remains the same as the previous designs some internal changes were made, more precisely thicker armour of 140mm Deck and 363mm Belt armour. Even with the weight saved by using a twin turret and 2 less cannons the displacement was risen to 44.800tons from the base 43.700tons!

While C-5 utilises the turret layout of the British King George V class battleships, the C-6 version modified so the two forward turrets were triples providing a more even weight distribution and a much better shape for the citadel to follow the lines of the hull. This change resulted in an increase of displacement by a mere 100tons to 44.800tons from the previous design's 44.700tons