The Japanese J/CA/1918 cruiser design

The J/CA/1918 design has a snappier roll than I would like, but Springsharp is happy with the result, except that the belt might not cover the machinery and magazines completely! This design, like its predecessor, depends on light-weight machinery (of 32.1 SHP/ton, not very light-weight). The speed is now 33 knots with a somewhat better AA armament. The torpedo armament is increased to 16-21in TT. The date is too early to go with the 24in size. This is the Springsharp report:

J/CA/1918, Japan Heavy Cruiser laid down 1918 (Engine 1928)

Displacement:
 11,749 t light; 12,192 t standard; 13,400 t normal; 14,367 t full load

Dimensions: Length overall / water x beam x draught
 650.10 ft / 645.00 ft x 61.00 ft x 19.00 ft (normal load)
 198.15 m / 196.60 m x 18.59 m  x 5.79 m

Armament:
      8 - 8.00" / 203 mm guns (4x2 guns), 256.00lbs / 116.12kg shells, 1918 Model
   Breech loading guns in turrets (on barbettes)
   on centreline ends, evenly spread, 2 raised mounts - superfiring
      6 - 4.70" / 119 mm guns in single mounts, 51.91lbs / 23.55kg shells, 1918 Model
   Anti-aircraft guns in deck mounts with hoists
   on side, all amidships
      24 - 2.24" / 57.0 mm guns (12x2 guns), 5.65lbs / 2.56kg shells, 1918 Model
   Anti-aircraft guns in deck mounts 
   on side, all amidships, 6 raised mounts - superfiring
 Weight of broadside 2,495 lbs / 1,132 kg
 Shells per gun, main battery: 120
 16 - 21.0" / 533.4 mm above water torpedoes

Armour:
   - Belts:  Width (max) Length (avg)  Height (avg)
 Main: 3.50" / 89 mm 450.00 ft / 137.16 m 16.00 ft / 4.88 m
 Ends: Unarmoured
   Main Belt covers 107 % of normal length
   Main belt does not fully cover magazines and engineering spaces

   - Torpedo Bulkhead:
  1.00" / 25 mm 450.00 ft / 137.16 m 18.00 ft / 5.49 m

   - Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
 Main: 4.00" / 102 mm 2.00" / 51 mm  2.00" / 51 mm
 2nd: 2.00" / 51 mm       -         -

   - Armour deck: 2.00" / 51 mm, Conning tower: 4.00" / 102 mm

Machinery:
 Oil fired boilers, steam turbines, 
 Geared drive, 4 shafts, 116,627 shp / 87,004 Kw = 33.00 kts
 Range 7,500nm at 15.00 kts
 Bunker at max displacement = 2,175 tons

Complement:
 622 - 809

Cost:
 £2.363 million / $9.452 million

Distribution of weights at normal displacement:
 Armament: 312 tons, 2.3 %
 Armour: 2,764 tons, 20.6 %
    - Belts: 1,038 tons, 7.7 %
    - Torpedo bulkhead: 300 tons, 2.2 %
    - Armament: 286 tons, 2.1 %
    - Armour Deck: 1,092 tons, 8.2 %
    - Conning Tower: 49 tons, 0.4 %
 Machinery: 3,631 tons, 27.1 %
 Hull, fittings & equipment: 5,042 tons, 37.6 %
 Fuel, ammunition & stores: 1,651 tons, 12.3 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   15,326 lbs / 6,952 Kg = 59.9 x 8.0 " / 203 mm shells or 1.9 torpedoes
 Stability (Unstable if below 1.00): 1.25
 Metacentric height 3.6 ft / 1.1 m
 Roll period: 13.6 seconds
 Steadiness - As gun platform (Average = 50 %): 52 %
   - Recoil effect (Restricted arc if above 1.00): 0.55
 Seaboat quality  (Average = 1.00): 1.04

Hull form characteristics:
 Hull has rise forward of midbreak
 Block coefficient: 0.627
 Length to Beam Ratio: 10.57 : 1
 'Natural speed' for length: 25.40 kts
 Power going to wave formation at top speed: 58 %
 Trim (Max stability = 0, Max steadiness = 100): 50
 Bow angle (Positive = bow angles forward): 4.00 degrees
 Stern overhang: 3.00 ft / 0.91 m
 Freeboard (% = measuring location as a percentage of overall length):
    - Stem:  30.00 ft / 9.14 m
    - Forecastle (20 %): 25.00 ft / 7.62 m
    - Mid (50 %):  25.00 ft / 7.62 m (17.00 ft / 5.18 m aft of break)
    - Quarterdeck (15 %): 17.00 ft / 5.18 m
    - Stern:  17.00 ft / 5.18 m
    - Average freeboard: 21.40 ft / 6.52 m

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 157.5 %
  - Above water (accommodation/working, high = better): 134.6 %
 Waterplane Area: 29,519 Square feet or 2,742 Square metres
 Displacement factor (Displacement / loading): 107 %
 Structure weight / hull surface area: 108 lbs/sq ft or 530 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.98
  - Longitudinal: 1.13
  - Overall: 1.00
 Hull space for machinery, storage, compartmentation is cramped
 Room for accommodation and workspaces is excellent