My friend Cliff's BBX design

My friend Cliff conceived of his BBX design as accepting a low speed to achieve a strong armament and protection. I adjusted the characteristics to use the SHP and weights for protection and machinery that he wanted. The speed is actually better than the 20 knots he allowed. The displacement to achieve adequate strength is much greater than the 71,500 tons normal that he had hoped for. The reason is that the hull weight is much greater than the 18,800 tons he allowed. The Springsharp hull weight is 29,331 tons. This is the Springsharp report:

GB/BB/BBX Red Book, Great Britain Battleship laid down 1915 (Engine 1927)

Displacement:
 72,798 t light; 76,298 t standard; 80,500 t normal; 83,861 t full load

Dimensions: Length overall / water x beam x draught
 802.89 ft / 800.00 ft x 135.00 ft x 37.00 ft (normal load)
 244.72 m / 243.84 m x 41.15 m  x 11.28 m

Armament:
      9 - 20.00" / 508 mm guns (3x3 guns), 4,000.00lbs / 1,814.37kg shells, 1915 Model
   Breech loading guns in turrets (on barbettes)
   on centreline ends, majority forward, 1 raised mount - superfiring
      24 - 5.00" / 127 mm guns (12x2 guns), 62.50lbs / 28.35kg shells, 1915 Model
   Quick firing guns in turrets (on barbettes)
   on side, all amidships, 4 raised mounts - superfiring
 Weight of broadside 37,500 lbs / 17,010 kg
 Shells per gun, main battery: 90

Armour:
   - Belts:  Width (max) Length (avg)  Height (avg)
 Main: 21.0" / 533 mm 450.00 ft / 137.16 m 20.00 ft / 6.10 m
 Ends: Unarmoured
   Main Belt covers 87 % of normal length

   - Torpedo Bulkhead:
  8.00" / 203 mm 450.00 ft / 137.16 m 36.00 ft / 10.97 m

   - Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
 Main: 21.0" / 533 mm 15.0" / 381 mm  21.0" / 533 mm
 2nd: 5.00" / 127 mm 5.00" / 127 mm  5.00" / 127 mm

   - Armour deck: 8.00" / 203 mm, Conning tower: 21.00" / 533 mm

Machinery:
 Oil fired boilers, steam turbines, 
 Geared drive, 4 shafts, 94,524 shp / 70,515 Kw = 23.50 kts
 Range 8,500nm at 15.00 kts
 Bunker at max displacement = 7,563 tons

Complement:
 2,389 - 3,106

Cost:
 £10.041 million / $40.164 million

Distribution of weights at normal displacement:
 Armament: 4,688 tons, 5.8 %
 Armour: 35,796 tons, 44.5 %
    - Belts: 8,714 tons, 10.8 %
    - Torpedo bulkhead: 4,795 tons, 6.0 %
    - Armament: 8,573 tons, 10.6 %
    - Armour Deck: 12,870 tons, 16.0 %
    - Conning Tower: 843 tons, 1.0 %
 Machinery: 2,984 tons, 3.7 %
 Hull, fittings & equipment: 29,331 tons, 36.4 %
 Fuel, ammunition & stores: 7,702 tons, 9.6 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   135,250 lbs / 61,348 Kg = 33.8 x 20.0 " / 508 mm shells or 32.4 torpedoes
 Stability (Unstable if below 1.00): 1.10
 Metacentric height 9.4 ft / 2.9 m
 Roll period: 18.5 seconds
 Steadiness - As gun platform (Average = 50 %): 80 %
   - Recoil effect (Restricted arc if above 1.00): 0.72
 Seaboat quality  (Average = 1.00): 1.60

Hull form characteristics:
 Hull has a flush deck
 Block coefficient: 0.705
 Length to Beam Ratio: 5.93 : 1
 'Natural speed' for length: 28.28 kts
 Power going to wave formation at top speed: 45 %
 Trim (Max stability = 0, Max steadiness = 100): 50
 Bow angle (Positive = bow angles forward): 5.00 degrees
 Stern overhang: -2.00 ft / -0.61 m
 Freeboard (% = measuring location as a percentage of overall length):
    - Stem:  33.00 ft / 10.06 m
    - Forecastle (20 %): 26.00 ft / 7.92 m
    - Mid (50 %):  26.00 ft / 7.92 m
    - Quarterdeck (15 %): 26.00 ft / 7.92 m
    - Stern:  26.00 ft / 7.92 m
    - Average freeboard: 26.56 ft / 8.10 m

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 65.9 %
  - Above water (accommodation/working, high = better): 180.3 %
 Waterplane Area: 86,957 Square feet or 8,079 Square metres
 Displacement factor (Displacement / loading): 102 %
 Structure weight / hull surface area: 257 lbs/sq ft or 1,253 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.95
  - Longitudinal: 1.55
  - Overall: 1.00
 Hull space for machinery, storage, compartmentation is excellent
 Room for accommodation and workspaces is excellent
 Ship has slow, easy roll, a good, steady gun platform
 Excellent seaboat, comfortable, can fire her guns in the heaviest weather