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Friday, February 24, 2006

The J/CA/1927 design has small improvements

The J/CA/1927 design has two improvements. One is the increase in torpedo armament to 16-24in TT. The other improvement is an increase in range to 10,000nm at 15 knots. The real Japanese cruisers were smaller with similar characteristics. The Atago class had a range of 8,500nm at 14 knots. The real Japanese cruisers had less deck armour and thicker side armour. This is the Springsharp report:
J/CA/1927, Japan Heavy Cruiser laid down 1927 (Engine 1939)

Displacement:
 13,236 t light; 13,759 t standard; 15,300 t normal; 16,533 t full load

Dimensions: Length overall / water x beam x draught
 680.80 ft / 675.00 ft x 62.00 ft x 22.00 ft (normal load)
 207.51 m / 205.74 m x 18.90 m  x 6.71 m

Armament:
      10 - 8.00" / 203 mm guns (5x2 guns), 256.00lbs / 116.12kg shells, 1927 Model
   Breech loading guns in turrets (on barbettes)
   on centreline ends, majority forward, 2 raised mounts - superfiring
      8 - 4.70" / 119 mm guns in single mounts, 51.91lbs / 23.55kg shells, 1927 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, 1927 Model
   Anti-aircraft guns in deck mounts 
   on side, all amidships, 6 raised mounts - superfiring
 Weight of broadside 3,111 lbs / 1,411 kg
 Shells per gun, main battery: 120
 16 - 24.0" / 609.6 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 103 % 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 20.00 ft / 6.10 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, 153,387 shp / 114,427 Kw = 35.00 kts
 Range 10,000nm at 15.00 kts
 Bunker at max displacement = 2,774 tons

Complement:
 687 - 894

Cost:
 £4.985 million / $19.940 million

Distribution of weights at normal displacement:
 Armament: 389 tons, 2.5 %
 Armour: 2,895 tons, 18.9 %
    - Belts: 1,040 tons, 6.8 %
    - Torpedo bulkhead: 333 tons, 2.2 %
    - Armament: 356 tons, 2.3 %
    - Armour Deck: 1,113 tons, 7.3 %
    - Conning Tower: 53 tons, 0.3 %
 Machinery: 4,150 tons, 27.1 %
 Hull, fittings & equipment: 5,801 tons, 37.9 %
 Fuel, ammunition & stores: 2,064 tons, 13.5 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   16,116 lbs / 7,310 Kg = 63.0 x 8.0 " / 203 mm shells or 2.0 torpedoes
 Stability (Unstable if below 1.00): 1.20
 Metacentric height 3.4 ft / 1.0 m
 Roll period: 14.0 seconds
 Steadiness - As gun platform (Average = 50 %): 51 %
   - Recoil effect (Restricted arc if above 1.00): 0.66
 Seaboat quality  (Average = 1.00): 1.02

Hull form characteristics:
 Hull has rise forward of midbreak
 Block coefficient: 0.582
 Length to Beam Ratio: 10.89 : 1
 'Natural speed' for length: 25.98 kts
 Power going to wave formation at top speed: 59 %
 Trim (Max stability = 0, Max steadiness = 100): 50
 Bow angle (Positive = bow angles forward): 5.00 degrees
 Stern overhang: 3.00 ft / 0.91 m
 Freeboard (% = measuring location as a percentage of overall length):
    - Stem:  32.00 ft / 9.75 m
    - Forecastle (20 %): 26.00 ft / 7.92 m
    - Mid (50 %):  26.00 ft / 7.92 m (18.00 ft / 5.49 m aft of break)
    - Quarterdeck (15 %): 18.00 ft / 5.49 m
    - Stern:  18.00 ft / 5.49 m
    - Average freeboard: 22.48 ft / 6.85 m

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 158.7 %
  - Above water (accommodation/working, high = better): 118.7 %
 Waterplane Area: 30,086 Square feet or 2,795 Square metres
 Displacement factor (Displacement / loading): 107 %
 Structure weight / hull surface area: 115 lbs/sq ft or 563 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.98
  - Longitudinal: 1.29
  - Overall: 1.00
 Hull space for machinery, storage, compartmentation is cramped
 Room for accommodation and workspaces is adequate

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