My friend Cliff's "BBX" design (GB/BB/1915)

In our wargame campaign from the early 1970's, my friend Cliff planned to build some very heavily armed and protected battleships that he called the "BBX". The designation was GB/BB/1915, as they would have been laid down in 1915 by the British navy. The ships were greatly beyond anything that would have been considered in that period, but they were the sort of ship we were considering at the time. This is Cliff's specification:

BBX
800ft x 135ft x 36.5ft (light)  Hull depth=60ft
Displacement=70,000 tons  Cp=0.64  Cm=0.97
9-20in/45 (202 ton) wt of AP shot=4,370 lbs at 2,700 ft/sec
24-5in QF guns (5 tons) 
Speed = 20 knots
SHP=89,300 tons at a normal displacement of 71,500 tons

Weights
18,800 tons  Hull
 2,450 tons  Aux Machinery
 2,980 tons  Machinery
 4,461 tons  Armament
35,709 tons  Protection
 5,600 tons  Miscellaneous

This is the Springsharp report that I was able to achieve:

GB/BB/1915 "BBX", Great Britain Battleship laid down 1915

Displacement:
 66,883 t light; 70,521 t standard; 77,066 t normal; 82,302 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
 (807.44 ft / 800.00 ft) x 135.00 ft x (37.00 / 39.17 ft)
 (246.11 m / 243.84 m) x 41.15 m  x (11.28 / 11.94 m)

Armament:
      9 - 20.00" / 508 mm 45.0 cal guns - 4,370.00lbs / 1,982.20kg shells, 90 per gun
   Breech loading guns in turret on barbette mounts, 1915 Model
   3 x Triple mounts on centreline ends, majority forward
  1 raised mount - superfiring
      24 - 5.00" / 127 mm 45.0 cal guns - 65.00lbs / 29.48kg shells, 150 per gun
   Quick firing guns in deck and hoist mounts, 1915 Model
   12 x Twin mounts on sides, aft deck forward
      Weight of broadside 40,890 lbs / 18,547 kg

Armour:
   - Belts:  Width (max) Length (avg)  Height (avg)
 Main: 18.0" / 457 mm 445.00 ft / 135.64 m 16.00 ft / 4.88 m
 Ends: Unarmoured
   Main Belt covers 86 % of normal length

   - Torpedo Bulkhead:
  8.00" / 203 mm 445.00 ft / 135.64 m 37.00 ft / 11.28 m

   - Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
 Main: 18.0" / 457 mm 12.0" / 305 mm  18.0" / 457 mm
 2nd: 5.00" / 127 mm 3.00" / 76 mm  5.00" / 127 mm

   - Armoured deck - multiple decks: 8.00" / 203 mm For and Aft decks
 Forecastle: 8.00" / 203 mm  Quarter deck: 8.00" / 203 mm

   - Conning towers: Forward 18.00" / 457 mm,  Aft 0.00" / 0 mm

Machinery:
 Oil fired boilers, steam turbines, 
 Geared drive, 4 shafts, 50,165 shp / 37,423 Kw = 20.00 kts
 Range 11,000nm at 15.00 kts
 Bunker at max displacement = 11,781 tons

Complement:
 2,312 - 3,006

Cost:
 £8.920 million / $35.682 million

Distribution of weights at normal displacement:
 Armament: 5,675 tons, 7.4 %
 Armour: 31,079 tons, 40.3 %
    - Belts: 5,949 tons, 7.7 %
    - Torpedo bulkhead: 4,874 tons, 6.3 %
    - Armament: 6,930 tons, 9.0 %
    - Armour Deck: 12,624 tons, 16.4 %
    - Conning Tower: 702 tons, 0.9 %
 Machinery: 1,900 tons, 2.5 %
 Hull, fittings & equipment: 28,229 tons, 36.6 %
 Fuel, ammunition & stores: 10,183 tons, 13.2 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   154,887 lbs / 70,256 Kg = 38.7 x 20.0 " / 508 mm shells or 40.6 torpedoes
 Stability (Unstable if below 1.00): 1.23
 Metacentric height 11.4 ft / 3.5 m
 Roll period: 16.8 seconds
 Steadiness - As gun platform (Average = 50 %): 85 %
   - Recoil effect (Restricted arc if above 1.00): 0.77
 Seaboat quality  (Average = 1.00): 1.70

Hull form characteristics:
 Hull has a flush deck,
   an extended bulbous bow and a cruiser stern
 Block coefficient (normal/deep): 0.675 / 0.681
 Length to Beam Ratio: 5.93 : 1
 'Natural speed' for length: 28.28 kts
 Power going to wave formation at top speed: 36 %
 Trim (Max stability = 0, Max steadiness = 100): 50
 Bow angle (Positive = bow angles forward): 12.00 degrees
 Stern overhang: 0.00 ft / 0.00 m
 Freeboard (% = length of deck as a percentage of waterline length):
    Fore end,  Aft end
    - Forecastle: 25.00 %,  35.00 ft / 10.67 m,  29.00 ft / 8.84 m
    - Forward deck: 30.00 %,  29.00 ft / 8.84 m,  25.00 ft / 7.62 m
    - Aft deck: 30.00 %,  25.00 ft / 7.62 m,  25.00 ft / 7.62 m
    - Quarter deck: 15.00 %,  25.00 ft / 7.62 m,  25.00 ft / 7.62 m
    - Average freeboard:  27.20 ft / 8.29 m

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 58.7 %
  - Above water (accommodation/working, high = better): 181.3 %
 Waterplane Area: 84,640 Square feet or 7,863 Square metres
 Displacement factor (Displacement / loading): 113 %
 Structure weight / hull surface area: 265 lbs/sq ft or 1,292 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.94
  - Longitudinal: 1.73
  - 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