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Saturday, May 02, 2009

My latest attempt at a very fast 1921-style battlecruiser

One of my long term obsessions is with very fast 1921-style battlecruisers. This latest one relies upon the lightest weight machinery to achieve 38 knots. The battlecruiser carries 6-16in/45 guns and has a 9in belt and 3in deck armour. This is the Springsharp design:
GB/CB/1921, Great Britain Fast Battlecruiser laid down 1921 (Engine 1950)

Displacement:
 41,653 t light; 43,329 t standard; 46,991 t normal; 49,921 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
 (889.32 ft / 874.00 ft) x 108.00 ft x (33.00 / 34.53 ft)
 (271.07 m / 266.40 m) x 32.92 m  x (10.06 / 10.52 m)

Armament:
      6 - 16.00" / 406 mm 45.0 cal guns - 2,065.00lbs / 936.67kg shells, 90 per gun
   Breech loading guns in turret on barbette mounts, 1921 Model
   2 x Triple mounts on centreline, forward deck forward
  1 raised mount - superfiring
      12 - 5.50" / 140 mm 50.0 cal guns - 85.00lbs / 38.56kg shells, 150 per gun
   Quick firing guns in turret on barbette mounts, 1921 Model
   6 x Single mounts on sides, aft deck forward
      6 - 4.70" / 119 mm 45.0 cal guns - 52.35lbs / 23.75kg shells, 150 per gun
   Anti-air guns in deck and hoist mounts, 1921 Model
   6 x Single mounts on sides, forward deck aft
  6 raised mounts
      32 - 1.57" / 40.0 mm 45.0 cal guns - 2.00lbs / 0.91kg shells, 150 per gun
   Anti-air guns in deck mounts, 1921 Model
   8 x 2 row quad mounts on sides, evenly spread
      Weight of broadside 13,788 lbs / 6,254 kg

Armour:
   - Belts:  Width (max) Length (avg)  Height (avg)
 Main: 9.00" / 229 mm 580.00 ft / 176.78 m 12.00 ft / 3.66 m
 Ends: Unarmoured
   Main Belt covers 102 % of normal length
   Main belt does not fully cover magazines and engineering spaces
   Main Belt inclined -10.00 degrees (positive = in)

   - Torpedo Bulkhead - Additional damage containing bulkheads:
  2.00" / 51 mm 580.00 ft / 176.78 m 33.00 ft / 10.06 m
 Beam between torpedo bulkheads 64.00 ft / 19.51 m

   - Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
 Main: 10.0" / 254 mm 8.00" / 203 mm  10.0" / 254 mm
 2nd: 4.00" / 102 mm 3.00" / 76 mm  4.00" / 102 mm

   - Armoured deck - multiple decks:
 For and Aft decks: 3.00" / 76 mm
 Forecastle: 3.00" / 76 mm  Quarter deck: 3.00" / 76 mm

   - Conning towers: Forward 8.00" / 203 mm, Aft 6.00" / 152 mm

Machinery:
 Oil fired boilers, steam turbines, 
 Geared drive, 6 shafts, 333,404 shp / 248,720 Kw = 38.00 kts
 Range 8,500nm at 18.00 kts
 Bunker at max displacement = 6,592 tons

Complement:
 1,595 - 2,074

Cost:
 £9.863 million / $39.453 million

Distribution of weights at normal displacement:
 Armament: 2,448 tons, 5.2 %
    - Guns: 2,448 tons, 5.2 %
 Armour: 11,045 tons, 23.5 %
    - Belts: 2,633 tons, 5.6 %
    - Torpedo bulkhead: 1,416 tons, 3.0 %
    - Armament: 2,847 tons, 6.1 %
    - Armour Deck: 3,756 tons, 8.0 %
    - Conning Towers: 393 tons, 0.8 %
 Machinery: 7,976 tons, 17.0 %
 Hull, fittings & equipment: 20,184 tons, 43.0 %
 Fuel, ammunition & stores: 5,338 tons, 11.4 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   72,600 lbs / 32,931 Kg = 35.4 x 16.0 " / 406 mm shells or 9.4 torpedoes
 Stability (Unstable if below 1.00): 1.11
 Metacentric height 6.8 ft / 2.1 m
 Roll period: 17.3 seconds
 Steadiness - As gun platform (Average = 50 %): 56 %
   - Recoil effect (Restricted arc if above 1.00): 0.66
 Seaboat quality  (Average = 1.00): 1.10

Hull form characteristics:
 Hull has rise forward of midbreak,
   an extended bulbous bow and large transom stern
 Block coefficient (normal/deep): 0.528 / 0.536
 Length to Beam Ratio: 8.09 : 1
 'Natural speed' for length: 34.21 kts
 Power going to wave formation at top speed: 60 %
 Trim (Max stability = 0, Max steadiness = 100): 51
 Bow angle (Positive = bow angles forward): 18.00 degrees
 Stern overhang: 2.00 ft / 0.61 m
 Freeboard (% = length of deck as a percentage of waterline length):
    Fore end,  Aft end
    - Forecastle: 25.00 %,  41.00 ft / 12.50 m,  36.00 ft / 10.97 m
    - Forward deck: 30.00 %,  36.00 ft / 10.97 m,  33.00 ft / 10.06 m
    - Aft deck: 30.00 %,  32.00 ft / 9.75 m,  32.00 ft / 9.75 m
    - Quarter deck: 15.00 %,  32.00 ft / 9.75 m,  32.00 ft / 9.75 m
    - Average freeboard:  34.25 ft / 10.44 m

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 135.7 %
  - Above water (accommodation/working, high = better): 266.6 %
 Waterplane Area: 67,154 Square feet or 6,239 Square metres
 Displacement factor (Displacement / loading): 119 %
 Structure weight / hull surface area: 209 lbs/sq ft or 1,021 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.94
  - Longitudinal: 1.84
  - Overall: 1.00
 Cramped machinery, storage, compartmentation space
 Excellent accommodation and workspace room

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