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Sunday, December 18, 2005

The GB/CA/1921 design

I was greatly tempted to switch to light weight machinery, but I did not want to alter the series that way. I probably will try a new series with light weight machinery, to demonstrate the radical difference that I know it makes. The GB/CA/1921 does have a flush deck and triple 8in turrets, along with dual-purpose 4.7in guns. The speed is now 33 knots. The armour basis is still 4in and the deck is 2in. This is the Springsharp report:
GB/CA/1921, Great Britain Heavy Cruiser laid down 1921

Displacement:
 13,824 t light; 14,377 t standard; 15,600 t normal; 16,579 t full load

Dimensions: Length overall / water x beam x draught
 627.03 ft / 625.00 ft x 63.00 ft x 23.00 ft (normal load)
 191.12 m / 190.50 m x 19.20 m  x 7.01 m

Armament:
      9 - 8.00" / 203 mm guns (3x3 guns), 256.00lbs / 116.12kg shells, 1921 Model
   Breech loading guns in turrets (on barbettes)
   on centreline ends, majority forward, 1 raised mount - superfiring
      8 - 4.70" / 119 mm guns (4x2 guns), 51.91lbs / 23.55kg shells, 1921 Model
   Dual purpose guns in deck mounts with hoists
   on side, all amidships
      24 - 1.57" / 40.0 mm guns (6x4 guns), 2.00lbs / 0.91kg shells, 1921 Model
   Anti-aircraft guns in deck mounts 
   on side, evenly spread
      4 - 0.00" / 0.0 mm guns in single mounts, 0.00lbs / 0.00kg shells, 1921 Model
   Breech loading guns in deck mount 
   on side, evenly spread
 Weight of broadside 2,767 lbs / 1,255 kg
 Shells per gun, main battery: 150
 16 - 21.0" / 533.4 mm above water torpedoes

Armour:
   - Belts:  Width (max) Length (avg)  Height (avg)
 Main: 4.00" / 102 mm 590.00 ft / 179.83 m 14.00 ft / 4.27 m
 Ends: Unarmoured
   Main Belt covers 145 % of normal length
   Main belt does not fully cover magazines and engineering spaces

   - Torpedo Bulkhead:
  1.00" / 25 mm 590.00 ft / 179.83 m 22.00 ft / 6.71 m

   - Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
 Main: 4.00" / 102 mm 3.00" / 76 mm  4.00" / 102 mm
 2nd: 2.00" / 51 mm 2.00" / 51 mm  2.00" / 51 mm

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

Machinery:
 Oil fired boilers, steam turbines, 
 Direct drive, 4 shafts, 129,200 shp / 96,383 Kw = 33.00 kts
 Range 6,500nm at 15.00 kts
 Bunker at max displacement = 2,202 tons

Complement:
 697 - 907

Cost:
 £3.556 million / $14.226 million

Distribution of weights at normal displacement:
 Armament: 346 tons, 2.2 %
 Armour: 3,397 tons, 21.8 %
    - Belts: 1,303 tons, 8.4 %
    - Torpedo bulkhead: 480 tons, 3.1 %
    - Armament: 492 tons, 3.2 %
    - Armour Deck: 1,068 tons, 6.8 %
    - Conning Tower: 54 tons, 0.3 %
 Machinery: 4,449 tons, 28.5 %
 Hull, fittings & equipment: 5,632 tons, 36.1 %
 Fuel, ammunition & stores: 1,776 tons, 11.4 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   15,545 lbs / 7,051 Kg = 60.7 x 8.0 " / 203 mm shells or 2.0 torpedoes
 Stability (Unstable if below 1.00): 1.19
 Metacentric height 3.4 ft / 1.0 m
 Roll period: 14.3 seconds
 Steadiness - As gun platform (Average = 50 %): 55 %
   - Recoil effect (Restricted arc if above 1.00): 0.61
 Seaboat quality  (Average = 1.00): 1.10

Hull form characteristics:
 Hull has a flush deck
 Block coefficient: 0.603
 Length to Beam Ratio: 9.92 : 1
 'Natural speed' for length: 25.00 kts
 Power going to wave formation at top speed: 60 %
 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:  29.00 ft / 8.84 m
    - Forecastle (20 %): 23.00 ft / 7.01 m
    - Mid (67 %):  23.00 ft / 7.01 m
    - Quarterdeck (15 %): 23.00 ft / 7.01 m
    - Stern:  23.00 ft / 7.01 m
    - Average freeboard: 23.48 ft / 7.16 m

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 161.0 %
  - Above water (accommodation/working, high = better): 130.7 %
 Waterplane Area: 28,876 Square feet or 2,683 Square metres
 Displacement factor (Displacement / loading): 104 %
 Structure weight / hull surface area: 115 lbs/sq ft or 561 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.95
  - Longitudinal: 1.59
  - Overall: 1.00
 Hull space for machinery, storage, compartmentation is cramped
 Room for accommodation and workspaces is excellent

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