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Sunday, January 21, 2007

I thought I should try a more Amagi-like British battlecruiser

I believe that the Japanese Amagi class ships only had a 10in belt, so I thought that I should redesign my British ship to be more like that. I was also not happy with the great displacement that was required. This is the Springsharp report for the revised design:
GB/CB/1921 Modified, Great Britain Battlecruiser laid down 1921

Displacement:
 41,058 t light; 43,093 t standard; 45,500 t normal; 47,425 t full load

Dimensions: Length overall / water x beam x draught
 814.00 ft / 814.00 ft x 104.00 ft x 31.00 ft (normal load)
 248.11 m / 248.11 m x 31.70 m  x 9.45 m

Armament:
      8 - 16.00" / 406 mm guns (4x2 guns), 2,048.00lbs / 928.96kg shells, 1921 Model
   Breech loading guns in turrets (on barbettes)
   on centreline ends, evenly spread, 2 raised mounts - superfiring
      2 - 16.00" / 406 mm guns (1x2 guns), 2,048.00lbs / 928.96kg shells, 1921 Model
   Breech loading guns in a turret (on a barbette)
   on side amidships
      14 - 6.00" / 152 mm guns in single mounts, 108.00lbs / 48.99kg shells, 1921 Model
   Quick firing guns in casemate mounts 
   on side, evenly spread
   14 guns in hull casemates - Limited use in heavy seas
 Weight of broadside 21,992 lbs / 9,975 kg
 Shells per gun, main battery: 90

Armour:
   - Belts:  Width (max) Length (avg)  Height (avg)
 Main: 10.0" / 254 mm 505.00 ft / 153.92 m 8.00 ft / 2.44 m
 Ends: Unarmoured
 Upper: 8.00" / 203 mm 505.00 ft / 153.92 m 8.00 ft / 2.44 m
   Main Belt covers 95 % of normal length
   Main belt does not fully cover magazines and engineering spaces

   - Torpedo Bulkhead:
  2.00" / 51 mm 505.00 ft / 153.92 m 31.00 ft / 9.45 m

   - Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
 Main: 12.0" / 305 mm 8.00" / 203 mm  12.0" / 305 mm
 2nd: 12.0" / 305 mm 8.00" / 203 mm  12.0" / 305 mm
 3rd: 6.00" / 152 mm 4.00" / 102 mm  6.00" / 152 mm

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

Machinery:
 Oil fired boilers, steam turbines, 
 Geared drive, 4 shafts, 159,219 shp / 118,777 Kw = 30.00 kts
 Range 6,500nm at 15.00 kts
 Bunker at max displacement = 4,332 tons

Complement:
 1,556 - 2,024

Cost:
 £11.490 million / $45.959 million

Distribution of weights at normal displacement:
 Armament: 2,749 tons, 6.0 %
 Armour: 13,643 tons, 30.0 %
    - Belts: 3,143 tons, 6.9 %
    - Torpedo bulkhead: 1,158 tons, 2.5 %
    - Armament: 4,401 tons, 9.7 %
    - Armour Deck: 4,611 tons, 10.1 %
    - Conning Tower: 330 tons, 0.7 %
 Machinery: 5,483 tons, 12.0 %
 Hull, fittings & equipment: 19,183 tons, 42.2 %
 Fuel, ammunition & stores: 4,442 tons, 9.8 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   53,947 lbs / 24,470 Kg = 26.3 x 16.0 " / 406 mm shells or 7.2 torpedoes
 Stability (Unstable if below 1.00): 1.08
 Metacentric height 6.1 ft / 1.9 m
 Roll period: 17.7 seconds
 Steadiness - As gun platform (Average = 50 %): 55 %
   - Recoil effect (Restricted arc if above 1.00): 0.84
 Seaboat quality  (Average = 1.00): 1.11

Hull form characteristics:
 Hull has rise forward of midbreak
 Block coefficient: 0.607
 Length to Beam Ratio: 7.83 : 1
 'Natural speed' for length: 28.53 kts
 Power going to wave formation at top speed: 51 %
 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:  31.00 ft / 9.45 m
    - Forecastle (20 %): 28.00 ft / 8.53 m
    - Mid (50 %):  28.00 ft / 8.53 m (20.00 ft / 6.10 m aft of break)
    - Quarterdeck (15 %): 20.00 ft / 6.10 m
    - Stern:  20.00 ft / 6.10 m
    - Average freeboard: 24.24 ft / 7.39 m
 Ship tends to be wet forward

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 104.4 %
  - Above water (accommodation/working, high = better): 180.7 %
 Waterplane Area: 62,311 Square feet or 5,789 Square metres
 Displacement factor (Displacement / loading): 98 %
 Structure weight / hull surface area: 219 lbs/sq ft or 1,070 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.98
  - Longitudinal: 1.20
  - Overall: 1.00
 Hull space for machinery, storage, compartmentation is adequate
 Room for accommodation and workspaces is excellent

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