A faster version of the BBX with 18in guns

I have a pencil inboard profile of my friend Cliff's design for the BBX (GB/BB/1915) super battleship. This version had a higher speed (28.3 knots with 179,000 SHP). The Springsharp power calculation came out very close to this (178,317 SHP), which is pretty amazing, considering that the early 1970's calculation was based on SHP/ton of displacement and Speed-Length ratios measured from not very good data about real ships. This is the Springsharp report:

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

Displacement:
 65,488 t light; 68,448 t standard; 71,500 t normal; 73,941 t full load

Dimensions: Length overall / water x beam x draught
 801.22 ft / 800.00 ft x 135.00 ft x 35.50 ft (normal load)
 244.21 m / 243.84 m x 41.15 m  x 10.82 m

Armament:
      9 - 18.00" / 457 mm guns (3x3 guns), 3,200.00lbs / 1,451.50kg 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 30,300 lbs / 13,744 kg
 Shells per gun, main battery: 90

Armour:
   - Belts:  Width (max) Length (avg)  Height (avg)
 Main: 18.0" / 457 mm 540.00 ft / 164.59 m 17.00 ft / 5.18 m
 Ends: Unarmoured
   Main Belt covers 104 % of normal length

   - Torpedo Bulkhead:
  4.00" / 102 mm 540.00 ft / 164.59 m 33.00 ft / 10.06 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 5.00" / 127 mm  5.00" / 127 mm

   - Armour deck: 8.00" / 203 mm, Conning tower: 18.00" / 457 mm

Machinery:
 Oil fired boilers, steam turbines, 
 Geared drive, 4 shafts, 178,317 shp / 133,024 Kw = 28.30 kts
 Range 6,500nm at 15.00 kts
 Bunker at max displacement = 5,493 tons

Complement:
 2,186 - 2,842

Cost:
 £8.717 million / $34.870 million

Distribution of weights at normal displacement:
 Armament: 3,468 tons, 4.9 %
 Armour: 29,523 tons, 41.3 %
    - Belts: 7,257 tons, 10.1 %
    - Torpedo bulkhead: 2,637 tons, 3.7 %
    - Armament: 6,686 tons, 9.4 %
    - Armour Deck: 12,275 tons, 17.2 %
    - Conning Tower: 668 tons, 0.9 %
 Machinery: 5,629 tons, 7.9 %
 Hull, fittings & equipment: 26,868 tons, 37.6 %
 Fuel, ammunition & stores: 6,012 tons, 8.4 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   114,341 lbs / 51,864 Kg = 39.2 x 18.0 " / 457 mm shells or 22.5 torpedoes
 Stability (Unstable if below 1.00): 1.15
 Metacentric height 10.3 ft / 3.1 m
 Roll period: 17.7 seconds
 Steadiness - As gun platform (Average = 50 %): 57 %
   - Recoil effect (Restricted arc if above 1.00): 0.49
 Seaboat quality  (Average = 1.00): 1.15

Hull form characteristics:
 Hull has a flush deck
 Block coefficient: 0.653
 Length to Beam Ratio: 5.93 : 1
 'Natural speed' for length: 28.28 kts
 Power going to wave formation at top speed: 54 %
 Trim (Max stability = 0, Max steadiness = 100): 50
 Bow angle (Positive = bow angles forward): 2.00 degrees
 Stern overhang: 0.00 ft / 0.00 m
 Freeboard (% = measuring location as a percentage of overall length):
    - Stem:  35.00 ft / 10.67 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: 26.72 ft / 8.14 m

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 73.4 %
  - Above water (accommodation/working, high = better): 187.9 %
 Waterplane Area: 82,940 Square feet or 7,705 Square metres
 Displacement factor (Displacement / loading): 104 %
 Structure weight / hull surface area: 246 lbs/sq ft or 1,202 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.96
  - Longitudinal: 1.55
  - Overall: 1.00
 Hull space for machinery, storage, compartmentation is excellent
 Room for accommodation and workspaces is excellent