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Thursday, August 16, 2007

A very fast British heavy cruiser

I intended that this be a companion design for the very fast light cruiser that I designed. This is a 37 knot heavy cruiser with 9-8in/55 BLR, 6-4.7in AA, and 24-2pdr AA guns. The belt is 4in, the deck is 2in, and there is a 1in torpedo bulkhead. That makes for a very well-protected ship. I suspect that given how easy this design was, that an even faster ship is possible. This is the Springsharp report:
GB/CA/1921 very fast, Great Britain Heavy Cruiser laid down 1921 (Engine 1950)

Displacement:
 15,751 t light; 16,324 t standard; 17,757 t normal; 18,903 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
 (744.54 ft / 734.00 ft) x 72.00 ft x (21.00 / 22.04 ft)
 (226.94 m / 223.72 m) x 21.95 m  x (6.40 / 6.72 m)

Armament:
      9 - 8.00" / 203 mm 55.0 cal guns - 250.00lbs / 113.40kg shells, 150 per gun
   Breech loading guns in turret on barbette mounts, 1921 Model
   3 x Triple mounts on centreline ends, majority forward
  1 raised mount - superfiring
      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
      24 - 1.57" / 40.0 mm 45.0 cal guns - 1.97lbs / 0.89kg shells, 150 per gun
   Anti-air guns in deck mounts, 1921 Model
   6 x 2 row quad mounts on sides, aft deck forward
  6 raised mounts
      Weight of broadside 2,611 lbs / 1,185 kg

Armour:
   - Belts:  Width (max) Length (avg)  Height (avg)
 Main: 4.00" / 102 mm 460.00 ft / 140.21 m 12.00 ft / 3.66 m
 Ends: Unarmoured
   Main Belt covers 96 % of normal length
   Main belt does not fully cover magazines and engineering spaces

   - Torpedo Bulkhead:
  1.00" / 25 mm 460.00 ft / 140.21 m 21.00 ft / 6.40 m

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

   - Armoured deck - multiple decks: 2.00" / 51 mm For and Aft decks
 Forecastle: 2.00" / 51 mm  Quarter deck: 2.00" / 51 mm

   - Conning towers: Forward 4.00" / 102 mm,  Aft 0.00" / 0 mm

Machinery:
 Oil fired boilers, steam turbines, 
 Geared drive, 4 shafts, 177,809 shp / 132,646 Kw = 37.00 kts
 Range 7,500nm at 16.00 kts
 Bunker at max displacement = 2,580 tons

Complement:
 768 - 999

Cost:
 £3.729 million / $14.915 million

Distribution of weights at normal displacement:
 Armament: 779 tons, 4.4 %
 Armour: 3,242 tons, 18.3 %
    - Belts: 915 tons, 5.2 %
    - Torpedo bulkhead: 357 tons, 2.0 %
    - Armament: 466 tons, 2.6 %
    - Armour Deck: 1,445 tons, 8.1 %
    - Conning Tower: 59 tons, 0.3 %
 Machinery: 4,254 tons, 24.0 %
 Hull, fittings & equipment: 7,476 tons, 42.1 %
 Fuel, ammunition & stores: 2,006 tons, 11.3 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   26,675 lbs / 12,099 Kg = 104.2 x 8.0 " / 203 mm shells or 3.1 torpedoes
 Stability (Unstable if below 1.00): 1.10
 Metacentric height 3.7 ft / 1.1 m
 Roll period: 15.8 seconds
 Steadiness - As gun platform (Average = 50 %): 64 %
   - Recoil effect (Restricted arc if above 1.00): 0.50
 Seaboat quality  (Average = 1.00): 1.28

Hull form characteristics:
 Hull has rise forward of midbreak,
   an extended bulbous bow and large transom stern
 Block coefficient (normal/deep): 0.560 / 0.568
 Length to Beam Ratio: 10.19 : 1
 'Natural speed' for length: 30.68 kts
 Power going to wave formation at top speed: 59 %
 Trim (Max stability = 0, Max steadiness = 100): 50
 Bow angle (Positive = bow angles forward): 13.00 degrees
 Stern overhang: 2.00 ft / 0.61 m
 Freeboard (% = length of deck as a percentage of waterline length):
    Fore end,  Aft end
    - Forecastle: 30.00 %,  37.00 ft / 11.28 m,  31.00 ft / 9.45 m
    - Forward deck: 30.00 %,  31.00 ft / 9.45 m,  31.00 ft / 9.45 m
    - Aft deck: 25.00 %,  23.00 ft / 7.01 m,  23.00 ft / 7.01 m
    - Quarter deck: 15.00 %,  23.00 ft / 7.01 m,  23.00 ft / 7.01 m
    - Average freeboard:  28.52 ft / 8.69 m

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 130.7 %
  - Above water (accommodation/working, high = better): 263.1 %
 Waterplane Area: 38,768 Square feet or 3,602 Square metres
 Displacement factor (Displacement / loading): 120 %
 Structure weight / hull surface area: 122 lbs/sq ft or 597 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.94
  - Longitudinal: 1.84
  - Overall: 1.00
 Hull space for machinery, storage, compartmentation is cramped
 Room for accommodation and workspaces is excellent
 Good seaboat, rides out heavy weather easily

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