The GB/CA/1931 design

With the growth in the design series for the British heavy cruiser, I thought that the next obvious step would be to add a fourth triple-8in turret, bringing the main armament up to 12-8in BLR. I tried switching the 8in guns to QF, but Springsharp will not allow QF for 8in guns. Of course, in the 1890's, British armament manufacturers built 8in QF guns for use in Elswick cruisers. This is the Springsharp report:

GB/CA/1931, Great Britain Heavy Cruiser laid down 1931

Displacement:
 16,864 t light; 17,573 t standard; 18,950 t normal; 20,051 t full load

Dimensions: Length overall / water x beam x draught
 687.00 ft / 687.00 ft x 68.00 ft x 25.00 ft (normal load)
 209.40 m / 209.40 m x 20.73 m  x 7.62 m

Armament:
      12 - 8.00" / 203 mm guns (4x3 guns), 256.00lbs / 116.12kg shells, 1931 Model
   Breech loading guns in turrets (on barbettes)
   on centreline ends, evenly spread, 2 raised mounts - superfiring
      12 - 4.70" / 119 mm guns (6x2 guns), 51.91lbs / 23.55kg shells, 1931 Model
   Dual purpose guns in turrets (on barbettes)
   on side, all amidships
      40 - 1.57" / 40.0 mm guns (10x4 guns), 2.00lbs / 0.91kg shells, 1931 Model
   Anti-aircraft guns in deck mounts 
   on side, evenly spread
 Weight of broadside 3,775 lbs / 1,712 kg
 Shells per gun, main battery: 150
 16 - 21.0" / 533.4 mm above water torpedoes

Armour:
   - Belts:  Width (max) Length (avg)  Height (avg)
 Main: 4.00" / 102 mm 640.00 ft / 195.07 m 5.00 ft / 1.52 m
 Ends: Unarmoured
   Main Belt covers 143 % of normal length

   - Torpedo Bulkhead:
  1.00" / 25 mm 640.00 ft / 195.07 m 24.00 ft / 7.32 m

   - Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
 Main: 5.00" / 127 mm 3.00" / 76 mm  5.00" / 127 mm
 2nd: 2.00" / 51 mm 2.00" / 51 mm  2.00" / 51 mm
 3rd: 1.00" / 25 mm       -         -

   - Armour deck: 4.00" / 102 mm, Conning tower: 5.00" / 127 mm

Machinery:
 Oil fired boilers, steam turbines, 
 Geared drive, 4 shafts, 151,776 shp / 113,225 Kw = 35.00 kts
 Range 7,500nm at 15.00 kts
 Bunker at max displacement = 2,478 tons

Complement:
 806 - 1,049

Cost:
 £7.077 million / $28.309 million

Distribution of weights at normal displacement:
 Armament: 472 tons, 2.5 %
 Armour: 4,646 tons, 24.5 %
    - Belts: 505 tons, 2.7 %
    - Torpedo bulkhead: 568 tons, 3.0 %
    - Armament: 940 tons, 5.0 %
    - Armour Deck: 2,555 tons, 13.5 %
    - Conning Tower: 77 tons, 0.4 %
 Machinery: 4,539 tons, 24.0 %
 Hull, fittings & equipment: 7,208 tons, 38.0 %
 Fuel, ammunition & stores: 2,086 tons, 11.0 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   22,983 lbs / 10,425 Kg = 89.8 x 8.0 " / 203 mm shells or 2.7 torpedoes
 Stability (Unstable if below 1.00): 1.11
 Metacentric height 3.4 ft / 1.0 m
 Roll period: 15.5 seconds
 Steadiness - As gun platform (Average = 50 %): 51 %
   - Recoil effect (Restricted arc if above 1.00): 0.69
 Seaboat quality  (Average = 1.00): 1.02

Hull form characteristics:
 Hull has a flush deck
   and transom stern
 Block coefficient: 0.568
 Length to Beam Ratio: 10.10 : 1
 'Natural speed' for length: 29.67 kts
 Power going to wave formation at top speed: 59 %
 Trim (Max stability = 0, Max steadiness = 100): 50
 Bow angle (Positive = bow angles forward): 0.00 degrees
 Stern overhang: 0.00 ft / 0.00 m
 Freeboard (% = measuring location as a percentage of overall length):
    - Stem:  31.00 ft / 9.45 m
    - Forecastle (20 %): 24.00 ft / 7.32 m
    - Mid (50 %):  24.00 ft / 7.32 m
    - Quarterdeck (15 %): 24.00 ft / 7.32 m
    - Stern:  24.00 ft / 7.32 m
    - Average freeboard: 24.56 ft / 7.49 m

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 137.9 %
  - Above water (accommodation/working, high = better): 149.6 %
 Waterplane Area: 34,531 Square feet or 3,208 Square metres
 Displacement factor (Displacement / loading): 108 %
 Structure weight / hull surface area: 127 lbs/sq ft or 622 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.96
  - Longitudinal: 1.46
  - Overall: 1.00
 Hull space for machinery, storage, compartmentation is cramped
 Room for accommodation and workspaces is excellent