This is bigger than I would have thought necessary: J/CB/1916

The J/CB/1916 has 8-16in guns and a speed of 30 knots. The armour basis is 11 inches. One reason for the size might be the deck armour being 4in, rather than the 3.5in I had considered. The speed is another reason, along with size needed to obtain the necessary hull strength. This is the Springsharp report:

J/CB/1916, Japan Battlecruiser laid down 1916

Displacement:
 40,755 t light; 42,597 t standard; 46,800 t normal; 50,162 t full load

Dimensions: Length overall / water x beam x draught
 767.17 ft / 765.00 ft x 102.00 ft x 32.00 ft (normal load)
 233.83 m / 233.17 m x 31.09 m  x 9.75 m

Armament:
      8 - 16.00" / 406 mm guns (4x2 guns), 2,048.00lbs / 928.96kg shells, 1916 Model
   Breech loading guns in turrets (on barbettes)
   on centreline ends, evenly spread, 2 raised mounts - superfiring
      16 - 5.50" / 140 mm guns in single mounts, 83.19lbs / 37.73kg shells, 1916 Model
   Quick firing guns in casemate mounts 
   on side, all amidships, 8 raised mounts - superfiring
      4 - 3.00" / 76.2 mm guns in single mounts, 13.50lbs / 6.12kg shells, 1916 Model
   Anti-aircraft guns in deck mounts with hoists
   on side, evenly spread, 2 raised mounts
      12 - 2.24" / 57.0 mm guns in single mounts, 5.65lbs / 2.56kg shells, 1916 Model
   Anti-aircraft guns in deck mounts 
   on side, evenly spread, 8 raised mounts
 Weight of broadside 17,837 lbs / 8,091 kg
 Shells per gun, main battery: 90

Armour:
   - Belts:  Width (max) Length (avg)  Height (avg)
 Main: 11.0" / 279 mm 630.00 ft / 192.02 m 17.00 ft / 5.18 m
 Ends: Unarmoured
   Main Belt covers 127 % of normal length

   - Torpedo Bulkhead:
  3.00" / 76 mm 630.00 ft / 192.02 m 31.00 ft / 9.45 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, 
 Geared drive, 4 shafts, 169,734 shp / 126,621 Kw = 30.00 kts
 Range 10,000nm at 15.00 kts
 Bunker at max displacement = 7,565 tons

Complement:
 1,590 - 2,068

Cost:
 £6.848 million / $27.390 million

Distribution of weights at normal displacement:
 Armament: 2,230 tons, 4.8 %
 Armour: 15,398 tons, 32.9 %
    - Belts: 4,855 tons, 10.4 %
    - Torpedo bulkhead: 2,168 tons, 4.6 %
    - Armament: 3,592 tons, 7.7 %
    - Armour Deck: 4,448 tons, 9.5 %
    - Conning Tower: 336 tons, 0.7 %
 Machinery: 6,324 tons, 13.5 %
 Hull, fittings & equipment: 16,803 tons, 35.9 %
 Fuel, ammunition & stores: 6,045 tons, 12.9 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   59,507 lbs / 26,992 Kg = 29.1 x 16.0 " / 406 mm shells or 8.8 torpedoes
 Stability (Unstable if below 1.00): 1.13
 Metacentric height 6.5 ft / 2.0 m
 Roll period: 16.8 seconds
 Steadiness - As gun platform (Average = 50 %): 53 %
   - Recoil effect (Restricted arc if above 1.00): 0.73
 Seaboat quality  (Average = 1.00): 1.06

Hull form characteristics:
 Hull has rise forward of midbreak
 Block coefficient: 0.656
 Length to Beam Ratio: 7.50 : 1
 'Natural speed' for length: 27.66 kts
 Power going to wave formation at top speed: 55 %
 Trim (Max stability = 0, Max steadiness = 100): 50
 Bow angle (Positive = bow angles forward): 4.00 degrees
 Stern overhang: -2.00 ft / -0.61 m
 Freeboard (% = measuring location as a percentage of overall length):
    - Stem:  31.00 ft / 9.45 m
    - Forecastle (20 %): 27.00 ft / 8.23 m
    - Mid (67 %):  27.00 ft / 8.23 m (19.00 ft / 5.79 m aft of break)
    - Quarterdeck (15 %): 19.00 ft / 5.79 m
    - Stern:  19.00 ft / 5.79 m
    - Average freeboard: 24.68 ft / 7.52 m

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 99.2 %
  - Above water (accommodation/working, high = better): 178.5 %
 Waterplane Area: 60,105 Square feet or 5,584 Square metres
 Displacement factor (Displacement / loading): 102 %
 Structure weight / hull surface area: 197 lbs/sq ft or 964 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.97
  - Longitudinal: 1.29
  - Overall: 1.00
 Hull space for machinery, storage, compartmentation is adequate
 Room for accommodation and workspaces is excellent