The GB/BB/1909 battleship design

This is a design that my friend Cliff had considered building as part of his program. It is just a 620ft long ship and has only 6-13.5in/45 and 12-6in QF guns. For a 29,000 ton ship (nominally), the ship is underarmed but well-protected, despite the belt being short. The real question is why the ship is as good as it is. I backed off coal-fired boilers as my photo is clearly an oil-fired ship, which is consistent with Cliff's plans. He often opted for speed and armour and sacrificed armament. Did I overlook something? In any case, here is the Springsharp report for those with sharp eyes to peruse:

GB/BB/1909, Great Britain Battleship laid down 1909

Displacement:
 23,901 t light; 24,964 t standard; 29,121 t normal; 32,447 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
 (628.00 ft / 620.00 ft) x 95.00 ft x (30.20 / 32.97 ft)
 (191.41 m / 188.98 m) x 28.96 m  x (9.20 / 10.05 m)

Armament:
      6 - 13.50" / 343 mm 45.0 cal guns - 1,240.67lbs / 562.76kg shells, 90 per gun
   Breech loading guns in turret on barbette mounts, 1909 Model
   3 x Twin mounts on centreline ends, majority forward
  1 raised mount - superfiring
      12 - 6.00" / 152 mm 45.0 cal guns - 108.93lbs / 49.41kg shells, 150 per gun
   Quick firing guns in casemate mounts, 1909 Model
   12 x Single mounts on sides, forward deck aft
      Weight of broadside 8,751 lbs / 3,969 kg

Armour:
   - Belts:  Width (max) Length (avg)  Height (avg)
 Main: 13.0" / 330 mm 385.00 ft / 117.35 m 9.00 ft / 2.74 m
 Ends: Unarmoured
 Upper: 10.0" / 254 mm 385.00 ft / 117.35 m 8.00 ft / 2.44 m
   Main Belt covers 96 % of normal length
   Main belt does not fully cover magazines and engineering spaces

   - Torpedo Bulkhead - Strengthened structural bulkheads:
  2.00" / 51 mm 385.00 ft / 117.35 m 30.20 ft / 9.20 m
 Beam between torpedo bulkheads 62.00 ft / 18.90 m

   - Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
 Main: 12.0" / 305 mm 9.00" / 229 mm  12.0" / 305 mm
 2nd: 4.00" / 102 mm 3.00" / 76 mm  4.00" / 102 mm

   - Protected deck - multiple decks:
 For and Aft decks: 4.00" / 102 mm
 Forecastle: 4.00" / 102 mm  Quarter deck: 4.00" / 102 mm

   - Conning towers: Forward 12.00" / 305 mm, Aft 9.00" / 229 mm

Machinery:
 Oil fired boilers, steam turbines, 
 Direct drive, 4 shafts, 76,183 shp / 56,832 Kw = 26.00 kts
 Range 8,500nm at 16.00 kts
 Bunker at max displacement = 7,482 tons

Complement:
 1,114 - 1,449

Cost:
 £2.077 million / $8.310 million

Distribution of weights at normal displacement:
 Armament: 1,501 tons, 5.2 %
    - Guns: 1,501 tons, 5.2 %
 Armour: 9,945 tons, 34.1 %
    - Belts: 3,325 tons, 11.4 %
    - Torpedo bulkhead: 860 tons, 3.0 %
    - Armament: 2,204 tons, 7.6 %
    - Armour Deck: 3,126 tons, 10.7 %
    - Conning Towers: 428 tons, 1.5 %
 Machinery: 3,463 tons, 11.9 %
 Hull, fittings & equipment: 8,992 tons, 30.9 %
 Fuel, ammunition & stores: 5,220 tons, 17.9 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   54,031 lbs / 24,508 Kg = 43.9 x 13.5 " / 343 mm shells or 8.6 torpedoes
 Stability (Unstable if below 1.00): 1.22
 Metacentric height 6.7 ft / 2.0 m
 Roll period: 15.5 seconds
 Steadiness - As gun platform (Average = 50 %): 74 %
   - Recoil effect (Restricted arc if above 1.00): 0.57
 Seaboat quality  (Average = 1.00): 1.47

Hull form characteristics:
 Hull has low quarterdeck ,
   a ram bow and a cruiser stern
 Block coefficient (normal/deep): 0.573 / 0.585
 Length to Beam Ratio: 6.53 : 1
 'Natural speed' for length: 24.90 kts
 Power going to wave formation at top speed: 53 %
 Trim (Max stability = 0, Max steadiness = 100): 50
 Bow angle (Positive = bow angles forward): -2.00 degrees
 Stern overhang: -2.00 ft / -0.61 m
 Freeboard (% = length of deck as a percentage of waterline length):
    Fore end,  Aft end
    - Forecastle: 28.00 %,  29.00 ft / 8.84 m,  27.00 ft / 8.23 m
    - Forward deck: 30.00 %,  27.00 ft / 8.23 m,  27.00 ft / 8.23 m
    - Aft deck: 9.00 %,  27.00 ft / 8.23 m,  27.00 ft / 8.23 m
    - Quarter deck: 33.00 %,  19.00 ft / 5.79 m,  19.00 ft / 5.79 m
    - Average freeboard:  24.58 ft / 7.49 m

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 96.3 %
  - Above water (accommodation/working, high = better): 193.9 %
 Waterplane Area: 42,002 Square feet or 3,902 Square metres
 Displacement factor (Displacement / loading): 121 %
 Structure weight / hull surface area: 170 lbs/sq ft or 828 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.93
  - Longitudinal: 1.95
  - Overall: 1.00
 Adequate machinery, storage, compartmentation space
 Excellent accommodation and workspace room
 Ship has slow, easy roll, a good, steady gun platform
 Good seaboat, rides out heavy weather easily