A fast heavy cruiser: the US/CA/1921 design

The next obvious step was to create a fast US heavy cruiser design. I thought that 35 knots would be adequate, as that would be comparable to what the Japanese were building or thinking of building. My design just has 9-8in/55 BLR, 8-5in/25 AA, 24-0.50in MG, and 8-21in TT. The armour basis is 4in and the deck is just 2in. I did include a torpedo bulkhead of 1in. This is the Springsharp report:

US/CA/1921, United States Heavy Cruiser laid down 1921 (Engine 1950)

Displacement:
 13,054 t light; 13,592 t standard; 14,993 t normal; 16,113 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
 (691.99 ft / 675.00 ft) x 65.00 ft x (20.00 / 21.22 ft)
 (210.92 m / 205.74 m) x 19.81 m  x (6.10 / 6.47 m)

Armament:
      9 - 8.00" / 203 mm 55.0 cal guns - 260.00lbs / 117.93kg shells, 150 per gun
   Breech loading guns in turret on barbette mounts, 1921 Model
   3 x Single mounts on centreline ends, majority forward
  1 raised mount - superfiring
      8 - 5.00" / 127 mm 25.0 cal guns - 56.00lbs / 25.40kg shells, 150 per gun
   Anti-air guns in deck and hoist mounts, 1921 Model
   8 x Single mounts on sides, aft deck forward
      24 - 0.50" / 12.7 mm 45.0 cal guns - 0.06lbs / 0.03kg shells, 500 per gun
   Anti-air guns in deck mounts, 1921 Model
   12 x Twin mounts on sides amidships
      Weight of broadside 2,790 lbs / 1,265 kg
      4 - 21.0" / 533 mm, 20.00 ft / 6.10 m torpedoes - 1.307 t each, 5.228 t total
 In 2 sets of deck mounted side rotating tubes

Armour:
   - Belts:  Width (max) Length (avg)  Height (avg)
 Main: 4.00" / 102 mm 450.00 ft / 137.16 m 12.00 ft / 3.66 m
 Ends: Unarmoured
   Main Belt covers 103 % of normal length
   Main belt does not fully cover magazines and engineering spaces

   - Torpedo Bulkhead:
  1.00" / 25 mm 450.00 ft / 137.16 m 20.00 ft / 6.10 m

   - Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
 Main: 4.00" / 102 mm 3.00" / 76 mm  4.00" / 102 mm

   - Armoured deck - multiple decks: 2.00" / 51 mm For and Aft decks

   - Conning towers: Forward 4.00" / 102 mm,  Aft 0.00" / 0 mm

Machinery:
 Oil fired boilers, steam turbines, 
 Geared drive, 4 shafts, 154,347 shp / 115,143 Kw = 35.00 kts
 Range 10,000nm at 15.00 kts
 Bunker at max displacement = 2,521 tons

Complement:
 676 - 880

Cost:
 £3.267 million / $13.067 million

Distribution of weights at normal displacement:
 Armament: 926 tons, 6.2 %
    - Guns: 921 tons, 6.1 %
    - Torpedoes: 5 tons, 0.0 %
 Armour: 2,811 tons, 18.7 %
    - Belts: 885 tons, 5.9 %
    - Torpedo bulkhead: 333 tons, 2.2 %
    - Armament: 539 tons, 3.6 %
    - Armour Deck: 1,002 tons, 6.7 %
    - Conning Tower: 52 tons, 0.3 %
 Machinery: 3,693 tons, 24.6 %
 Hull, fittings & equipment: 5,625 tons, 37.5 %
 Fuel, ammunition & stores: 1,938 tons, 12.9 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   19,492 lbs / 8,841 Kg = 76.1 x 8.0 " / 203 mm shells or 2.4 torpedoes
 Stability (Unstable if below 1.00): 1.10
 Metacentric height 3.2 ft / 1.0 m
 Roll period: 15.4 seconds
 Steadiness - As gun platform (Average = 50 %): 56 %
   - Recoil effect (Restricted arc if above 1.00): 0.61
 Seaboat quality  (Average = 1.00): 1.12

Hull form characteristics:
 Hull has rise forward of midbreak,
   an extended bulbous bow and a cruiser stern
 Block coefficient (normal/deep): 0.598 / 0.606
 Length to Beam Ratio: 10.38 : 1
 'Natural speed' for length: 25.98 kts
 Power going to wave formation at top speed: 59 %
 Trim (Max stability = 0, Max steadiness = 100): 50
 Bow angle (Positive = bow angles forward): 25.00 degrees
 Stern overhang: 3.00 ft / 0.91 m
 Freeboard (% = length of deck as a percentage of waterline length):
    Fore end,  Aft end
    - Forecastle: 16.00 %,  30.00 ft / 9.14 m,  30.00 ft / 9.14 m
    - Forward deck: 17.00 %,  30.00 ft / 9.14 m,  30.00 ft / 9.14 m
    - Aft deck: 52.00 %,  22.00 ft / 6.71 m,  22.00 ft / 6.71 m
    - Quarter deck: 15.00 %,  22.00 ft / 6.71 m,  22.00 ft / 6.71 m
    - Average freeboard:  24.64 ft / 7.51 m

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 143.2 %
  - Above water (accommodation/working, high = better): 213.9 %
 Waterplane Area: 32,030 Square feet or 2,976 Square metres
 Displacement factor (Displacement / loading): 114 %
 Structure weight / hull surface area: 116 lbs/sq ft or 568 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.95
  - Longitudinal: 1.50
  - Overall: 1.00
 Hull space for machinery, storage, compartmentation is cramped
 Room for accommodation and workspaces is excellent