The J/CL/1921 design

The J/CL/1921 design has a top speed of 35 knots, which is its main improvement over its predecessor. There is also a slightly improved AA armament, with 6-4.7in AA, and 24-57mm AA. The torpedo armament is increased to 8-21in TT. This is the Springsharp report:

J/CL/1921, Japan Light Cruiser laid down 1921 (Engine 1931)

Displacement:
 9,389 t light; 9,742 t standard; 10,500 t normal; 11,106 t full load

Dimensions: Length overall / water x beam x draught
 618.42 ft / 615.00 ft x 56.00 ft x 20.00 ft (normal load)
 188.49 m / 187.45 m x 17.07 m  x 6.10 m

Armament:
      8 - 6.00" / 152 mm guns (4x2 guns), 108.00lbs / 48.99kg shells, 1921 Model
   Quick firing guns in deck mounts with hoists
   on centreline ends, evenly spread, 2 raised mounts - superfiring
      6 - 4.70" / 119 mm guns in single mounts, 51.91lbs / 23.55kg shells, 1921 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, 1921 Model
   Anti-aircraft guns in deck mounts 
   on side, all amidships, 8 raised mounts - superfiring
 Weight of broadside 1,311 lbs / 595 kg
 Shells per gun, main battery: 180
 8 - 21.0" / 533.4 mm above water torpedoes

Armour:
   - Belts:  Width (max) Length (avg)  Height (avg)
 Main: 3.00" / 76 mm 475.00 ft / 144.78 m 12.00 ft / 3.66 m
 Ends: Unarmoured
   Main Belt covers 119 % of normal length
   Main belt does not fully cover magazines and engineering spaces

   - Torpedo Bulkhead:
  1.00" / 25 mm 475.00 ft / 144.78 m 18.00 ft / 5.49 m

   - Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
 Main: 3.00" / 76 mm 2.00" / 51 mm  2.00" / 51 mm

   - Armour deck: 1.00" / 25 mm, Conning tower: 3.00" / 76 mm

Machinery:
 Oil fired boilers, steam turbines, 
 Geared drive, 2 shafts, 123,623 shp / 92,222 Kw = 35.00 kts
 Range 5,600nm at 15.00 kts
 Bunker at max displacement = 1,364 tons

Complement:
 518 - 674

Cost:
 £2.504 million / $10.017 million

Distribution of weights at normal displacement:
 Armament: 164 tons, 1.6 %
 Armour: 1,559 tons, 14.8 %
    - Belts: 691 tons, 6.6 %
    - Torpedo bulkhead: 316 tons, 3.0 %
    - Armament: 83 tons, 0.8 %
    - Armour Deck: 438 tons, 4.2 %
    - Conning Tower: 31 tons, 0.3 %
 Machinery: 3,697 tons, 35.2 %
 Hull, fittings & equipment: 3,969 tons, 37.8 %
 Fuel, ammunition & stores: 1,111 tons, 10.6 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   8,735 lbs / 3,962 Kg = 80.9 x 6.0 " / 152 mm shells or 1.3 torpedoes
 Stability (Unstable if below 1.00): 1.31
 Metacentric height 3.4 ft / 1.0 m
 Roll period: 12.8 seconds
 Steadiness - As gun platform (Average = 50 %): 53 %
   - Recoil effect (Restricted arc if above 1.00): 0.38
 Seaboat quality  (Average = 1.00): 1.05

Hull form characteristics:
 Hull has rise forward of midbreak
 Block coefficient: 0.534
 Length to Beam Ratio: 10.98 : 1
 'Natural speed' for length: 24.80 kts
 Power going to wave formation at top speed: 60 %
 Trim (Max stability = 0, Max steadiness = 100): 50
 Bow angle (Positive = bow angles forward): 3.00 degrees
 Stern overhang: 2.00 ft / 0.61 m
 Freeboard (% = measuring location as a percentage of overall length):
    - Stem:  27.00 ft / 8.23 m
    - Forecastle (20 %): 23.00 ft / 7.01 m
    - Mid (67 %):  23.00 ft / 7.01 m (15.00 ft / 4.57 m aft of break)
    - Quarterdeck (15 %): 15.00 ft / 4.57 m
    - Stern:  15.00 ft / 4.57 m
    - Average freeboard: 20.68 ft / 6.30 m
 Ship tends to be wet forward

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 196.9 %
  - Above water (accommodation/working, high = better): 151.9 %
 Waterplane Area: 23,668 Square feet or 2,199 Square metres
 Displacement factor (Displacement / loading): 102 %
 Structure weight / hull surface area: 98 lbs/sq ft or 476 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.96
  - Longitudinal: 1.41
  - Overall: 1.00
 Hull space for machinery, storage, compartmentation is cramped
 Room for accommodation and workspaces is excellent