OK, so now how about the 15in-gunned fast battleship

We seem to be on a roll, so let us try the 15in-gunned fast battleship to be laid down in 1913. By accepting slightly lower protection than we might otherwise have, we have a 27-knot ship with a 17 knot cruising speed and a 5,600nm range. The armour basis is 12in, which should do quite well for a WWI-style ship. I actually reduced length and beam to achieve adequate composite strength. I also have lowered the freeboard for that same end. Does this seem reasonable and useful? This is the Springsharp report:

GB/BB/1913, Great Britain Battleship laid down 1913

Displacement:
 30,154 t light; 31,523 t standard; 34,500 t normal; 36,882 t full load

Dimensions: Length overall / water x beam x draught
 675.00 ft / 675.00 ft x 90.00 ft x 31.00 ft (normal load)
 205.74 m / 205.74 m x 27.43 m  x 9.45 m

Armament:
      8 - 15.00" / 381 mm guns (4x2 guns), 1,687.50lbs / 765.44kg shells, 1913 Model
   Breech loading guns in turrets (on barbettes)
   on centreline ends, evenly spread, 2 raised mounts - superfiring
      14 - 6.00" / 152 mm guns in single mounts, 108.00lbs / 48.99kg shells, 1913 Model
   Quick firing guns in casemate mounts 
   on side, evenly spread, 4 raised mounts
 Weight of broadside 15,012 lbs / 6,809 kg
 Shells per gun, main battery: 80
 4 - 21.0" / 533.4 mm submerged torpedo tubes

Armour:
   - Belts:  Width (max) Length (avg)  Height (avg)
 Main: 12.0" / 305 mm 450.00 ft / 137.16 m 16.00 ft / 4.88 m
 Ends: 5.00" / 127 mm 225.00 ft / 68.58 m 16.00 ft / 4.88 m
   Main Belt covers 103 % of normal length

   - Torpedo Bulkhead:
  2.00" / 51 mm 450.00 ft / 137.16 m 30.00 ft / 9.14 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: 5.00" / 127 mm 5.00" / 127 mm  5.00" / 127 mm

   - Armour deck: 4.00" / 102 mm, Conning tower: 12.00" / 305 mm

Machinery:
 Oil fired boilers, steam turbines, 
 Direct drive, 4 shafts, 95,921 shp / 71,557 Kw = 27.00 kts
 Range 5,600nm at 17.00 kts
 Bunker at max displacement = 5,359 tons

Complement:
 1,265 - 1,645

Cost:
 £3.445 million / $13.780 million

Distribution of weights at normal displacement:
 Armament: 1,877 tons, 5.4 %
 Armour: 12,127 tons, 35.1 %
    - Belts: 4,372 tons, 12.7 %
    - Torpedo bulkhead: 999 tons, 2.9 %
    - Armament: 3,066 tons, 8.9 %
    - Armour Deck: 3,416 tons, 9.9 %
    - Conning Tower: 274 tons, 0.8 %
 Machinery: 3,759 tons, 10.9 %
 Hull, fittings & equipment: 12,393 tons, 35.9 %
 Fuel, ammunition & stores: 4,346 tons, 12.6 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   41,367 lbs / 18,764 Kg = 24.5 x 15.0 " / 381 mm shells or 5.8 torpedoes
 Stability (Unstable if below 1.00): 1.05
 Metacentric height 4.7 ft / 1.4 m
 Roll period: 17.5 seconds
 Steadiness - As gun platform (Average = 50 %): 53 %
   - Recoil effect (Restricted arc if above 1.00): 0.92
 Seaboat quality  (Average = 1.00): 1.06

Hull form characteristics:
 Hull has rise forward of midbreak
 Block coefficient: 0.641
 Length to Beam Ratio: 7.50 : 1
 'Natural speed' for length: 25.98 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 (% = measuring location as a percentage of overall length):
    - Stem:  29.00 ft / 8.84 m
    - Forecastle (20 %): 24.00 ft / 7.32 m
    - Mid (67 %):  24.00 ft / 7.32 m (16.00 ft / 4.88 m aft of break)
    - Quarterdeck (15 %): 16.00 ft / 4.88 m
    - Stern:  16.00 ft / 4.88 m
    - Average freeboard: 21.76 ft / 6.63 m

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 100.5 %
  - Above water (accommodation/working, high = better): 151.4 %
 Waterplane Area: 46,162 Square feet or 4,289 Square metres
 Displacement factor (Displacement / loading): 100 %
 Structure weight / hull surface area: 185 lbs/sq ft or 903 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.97
  - Longitudinal: 1.33
  - Overall: 1.00
 Hull space for machinery, storage, compartmentation is adequate
 Room for accommodation and workspaces is excellent