A new take on the GB/BB/1902 design

I now guess that this specification for a pre-dreadnought battleship that dates from the early 1970's is for a ship from about 1902. The specification is quite detailed and overestimated the power required for the ship to reach its designed speed. As a consequence, the actual speed is higher, in my solution to the design:

Normal displacement=15,000 tons  435ft x 75ft x 50ft depth
Armament: 4-12in/40 and 12-6in/45 guns   Belt: 12in
Speed-18knots  Normal power=22,330 IHP

Weights:
4720 tons   Hull
1484 tons   Machinery
 564 tons   Aux Machinery
6352 tons   Protection
 680 tons   Armament
1200 tons   Miscellaneous

This is the Springsharp report:

GB/BB/1902, Great Britain Battleship laid down 1902

Displacement:
 12,670 t light; 13,248 t standard; 15,138 t normal; 16,650 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
 (439.00 ft / 435.00 ft) x 75.00 ft x (29.00 / 31.30 ft)
 (133.81 m / 132.59 m) x 22.86 m  x (8.84 / 9.54 m)

Armament:
      4 - 12.00" / 305 mm 40.0 cal guns - 828.07lbs / 375.60kg shells, 90 per gun
   Breech loading guns in turret on barbette mounts, 1902 Model
   2 x Twin mounts on centreline ends, evenly spread
      12 - 6.00" / 152 mm 45.0 cal guns - 108.92lbs / 49.41kg shells, 150 per gun
   Quick firing guns in casemate mounts, 1902 Model
   12 x Single mounts on sides, forward deck aft
  4 hull mounts in casemates- Limited use in heavy seas
      Weight of broadside 4,619 lbs / 2,095 kg

Armour:
   - Belts:  Width (max) Length (avg)  Height (avg)
 Main: 12.0" / 305 mm 250.00 ft / 76.20 m 8.00 ft / 2.44 m
 Ends: Unarmoured
 Upper: 8.00" / 203 mm 250.00 ft / 76.20 m 8.00 ft / 2.44 m
   Main Belt covers 88 % of normal length
   Main belt does not fully cover magazines and engineering spaces

   - Torpedo Bulkhead:
  1.00" / 25 mm 250.00 ft / 76.20 m 29.00 ft / 8.84 m

   - Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
 Main: 12.0" / 305 mm 7.00" / 178 mm  9.00" / 229 mm
 2nd: 7.00" / 178 mm 4.00" / 102 mm  7.00" / 178 mm

   - Protected deck - single deck: 3.00" / 76 mm For and Aft decks
 Forecastle: 2.00" / 51 mm  Quarter deck: 2.00" / 51 mm

   - Conning towers: Forward 9.00" / 229 mm,  Aft 0.00" / 0 mm

Machinery:
 Coal fired boilers, complex reciprocating steam engines, 
 Direct drive, 2 shafts, 22,728 ihp / 16,955 Kw = 20.50 kts
 Range 7,500nm at 12.00 kts
 Bunker at max displacement = 3,403 tons (100% coal)

Complement:
 682 - 887

Cost:
 £1.262 million / $5.049 million

Distribution of weights at normal displacement:
 Armament: 746 tons, 4.9 %
 Armour: 4,346 tons, 28.7 %
    - Belts: 1,822 tons, 12.0 %
    - Torpedo bulkhead: 268 tons, 1.8 %
    - Armament: 946 tons, 6.3 %
    - Armour Deck: 1,191 tons, 7.9 %
    - Conning Tower: 119 tons, 0.8 %
 Machinery: 3,444 tons, 22.7 %
 Hull, fittings & equipment: 4,135 tons, 27.3 %
 Fuel, ammunition & stores: 2,468 tons, 16.3 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   17,287 lbs / 7,841 Kg = 20.0 x 12.0 " / 305 mm shells or 2.5 torpedoes
 Stability (Unstable if below 1.00): 1.36
 Metacentric height 5.6 ft / 1.7 m
 Roll period: 13.4 seconds
 Steadiness - As gun platform (Average = 50 %): 91 %
   - Recoil effect (Restricted arc if above 1.00): 0.47
 Seaboat quality  (Average = 1.00): 1.83

Hull form characteristics:
 Hull has a flush deck,
   a ram bow and a cruiser stern
 Block coefficient (normal/deep): 0.560 / 0.571
 Length to Beam Ratio: 5.80 : 1
 'Natural speed' for length: 20.86 kts
 Power going to wave formation at top speed: 51 %
 Trim (Max stability = 0, Max steadiness = 100): 50
 Bow angle (Positive = bow angles forward): -3.00 degrees
 Stern overhang: -3.00 ft / -0.91 m
 Freeboard (% = length of deck as a percentage of waterline length):
    Fore end,  Aft end
    - Forecastle: 25.00 %,  25.00 ft / 7.62 m,  22.00 ft / 6.71 m
    - Forward deck: 30.00 %,  22.00 ft / 6.71 m,  19.00 ft / 5.79 m
    - Aft deck: 30.00 %,  19.00 ft / 5.79 m,  19.00 ft / 5.79 m
    - Quarter deck: 15.00 %,  19.00 ft / 5.79 m,  20.00 ft / 6.10 m
    - Average freeboard:  20.58 ft / 6.27 m

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 129.1 %
  - Above water (accommodation/working, high = better): 126.8 %
 Waterplane Area: 22,983 Square feet or 2,135 Square metres
 Displacement factor (Displacement / loading): 105 %
 Structure weight / hull surface area: 125 lbs/sq ft or 608 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.89
  - Longitudinal: 2.83
  - Overall: 1.00
 Hull space for machinery, storage, compartmentation is cramped
 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