The US/CB/1921 class

I tried a version of the US Lexington class battlecruisers from 1921 as the US/CB/1921 design in Springsharp 3.0b1 Beta. I found that the design worked reasonably well, except that I had to greatly increase the displacement, due to lack of strength. Springsharp also wants too much power to reach the designed speed, which is a large issue. Alt_Naval has a nice photo. This is the Springsharp report:

US/CB/1921, United States Battlecruiser laid down 1921

Displacement:
 44,973 t light; 47,236 t standard; 49,282 t normal; 50,919 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
 (866.30 ft / 850.00 ft) x 104.30 ft x (32.00 / 32.88 ft)
 (264.05 m / 259.08 m) x 31.79 m  x (9.75 / 10.02 m)

Armament:
      8 - 16.00" / 406 mm 50.0 cal guns - 2,100.00lbs / 952.54kg shells, 120 per gun
   Breech loading guns in turret on barbette mounts , 1921 Model
   4 x Twin mounts on centreline ends, evenly spread
  2 raised mounts - superfiring
      16 - 6.00" / 152 mm 53.0 cal guns - 115.00lbs / 52.16kg shells, 150 per gun
   Breech loading guns in casemate mounts , 1921 Model
   16 x Single mounts on sides, evenly spread
  8 raised mounts
      4 - 3.00" / 76.2 mm 50.0 cal guns - 14.00lbs / 6.35kg shells, 150 per gun
   Anti-air guns in deck and hoist mounts , 1921 Model
   4 x Single mounts on sides, evenly spread
  4 raised mounts
 Weight of broadside 18,696 lbs / 18,696 kg
 4 - 21.0" / 533 mm above water torpedoes

Armour:
   - Belts:  Width (max) Length (avg)  Height (avg)
 Main: 7.00" / 178 mm 540.00 ft / 164.59 m 16.00 ft / 4.88 m
 Ends: Unarmoured
   Main Belt covers 98 % of normal length
   Main belt does not fully cover magazines and engineering spaces

   - Torpedo Bulkhead:
  4.00" / 102 mm 540.00 ft / 164.59 m 32.00 ft / 9.75 m

   - Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
 Main: 11.0" / 279 mm 7.00" / 178 mm  9.00" / 229 mm
 2nd: 6.00" / 152 mm 4.00" / 102 mm  6.00" / 152 mm

   - Armour deck: 4.00" / 102 mm, Conning tower: 12.00" / 305 mm

Machinery:
 Oil fired boilers, steam turbines, 
 Electric cruising motors plus geared drives, 4 shafts, 254,027 shp / 189,504 Kw = 33.50 kts
 Range 12,000nm at 10.00 kts
 Bunker at max displacement = 3,682 tons

Complement:
 1,653 - 2,149

Cost:
 £11.975 million / $47.899 million

Distribution of weights at normal displacement:
 Armament: 3,469 tons, 7.0 %
 Armour: 13,727 tons, 27.9 %
    - Belts: 2,590 tons, 5.3 %
    - Torpedo bulkhead: 2,557 tons, 5.2 %
    - Armament: 3,398 tons, 6.9 %
    - Armour Deck: 4,834 tons, 9.8 %
    - Conning Tower: 348 tons, 0.7 %
 Machinery: 8,747 tons, 17.7 %
 Hull, fittings & equipment: 20,229 tons, 41.0 %
 Fuel, ammunition & stores: 4,309 tons, 8.7 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   62,171 lbs / 28,200 Kg = 30.4 x 16.0 " / 406 mm shells or 8.1 torpedoes
 Stability (Unstable if below 1.00): 1.12
 Metacentric height 6.6 ft / 2.0 m
 Roll period: 17.0 seconds
 Steadiness - As gun platform (Average = 50 %): 57 %
   - Recoil effect (Restricted arc if above 1.00): 0.92
 Seaboat quality  (Average = 1.00): 1.14

Hull form characteristics:
 Hull has low quarterdeck ,
   a straight bulbous bow and a cruiser stern
 Block coefficient (normal/deep): 0.608 / 0.611
 Length to Beam Ratio: 8.15 : 1
 'Natural speed' for length: 29.15 kts
 Power going to wave formation at top speed: 56 %
 Trim (Max stability = 0, Max steadiness = 100): 50
 Bow angle (Positive = bow angles forward): 27.00 degrees
 Stern overhang: -3.00 ft / -0.91 m
 Freeboard (% = length of deck as a percentage of waterline length):
    Fore end,  Aft end
    - Forecastle: 20.00 %,  32.00 ft / 9.75 m,  32.00 ft / 9.75 m
    - Forward deck: 30.00 %,  32.00 ft / 9.75 m,  32.00 ft / 9.75 m
    - Aft deck: 25.00 %,  32.00 ft / 9.75 m,  32.00 ft / 9.75 m
    - Quarter deck: 25.00 %,  24.00 ft / 7.32 m,  24.00 ft / 7.32 m
    - Average freeboard:  30.00 ft / 9.14 m
 Ship tends to be wet forward

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 114.9 %
  - Above water (accommodation/working, high = better): 233.4 %
 Waterplane Area: 65,327 Square feet or 6,069 Square metres
 Displacement factor (Displacement / loading): 100 %
 Structure weight / hull surface area: 209 lbs/sq ft or 1,022 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.96
  - Longitudinal: 1.41
  - Overall: 1.00
 Hull space for machinery, storage, compartmentation is cramped
 Room for accommodation and workspaces is excellent