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Thursday, July 19, 2007

A fast British 1921 light cruiser

The GB/CL/1921 "Fast" light cruiser was an attempt to see what might be achieved with Springsharp 3.0b2 Beta. This ship carried 9-6in/55 QF guns and 12-21in TT at a speed of 37 knots. It has a range of 5400nm at 15 knots. I added some protection, including a thin torpedo bulkhead. It would be heavily damaged, but might survive on torpedo. This is the Springsharp report:
GB/CL/1921 Fast, Great Britain Light Cruiser laid down 1921 (Engine 1941)

Displacement:
 10,647 t light; 10,984 t standard; 11,752 t normal; 12,366 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
 (622.04 ft / 614.00 ft) x 58.00 ft x (22.00 / 22.85 ft)
 (189.60 m / 187.15 m) x 17.68 m  x (6.71 / 6.97 m)

Armament:
      9 - 6.00" / 152 mm 55.0 cal guns - 115.00lbs / 52.16kg shells, 150 per gun
   Quick firing guns in turret on barbette mounts, 1921 Model
   3 x Triple mounts on centreline ends, majority aft
  1 raised mount aft - superfiring
      Weight of broadside 1,035 lbs / 469 kg
      12 - 21.0" / 533 mm, 20.00 ft / 6.10 m torpedoes - 1.307 t each, 15.683 t total
 In 4 sets of deck mounted carriage/fixed tubes

Armour:
   - Belts:  Width (max) Length (avg)  Height (avg)
 Main: 3.00" / 76 mm 400.00 ft / 121.92 m 10.00 ft / 3.05 m
 Ends: Unarmoured
   Main Belt covers 100 % of normal length
   Main belt does not fully cover magazines and engineering spaces

   - Torpedo Bulkhead:
  0.70" / 18 mm 400.00 ft / 121.92 m 22.00 ft / 6.71 m

   - Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
 Main: 3.00" / 76 mm 2.00" / 51 mm  3.00" / 76 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 3.00" / 76 mm,  Aft 0.00" / 0 mm

Machinery:
 Oil fired boilers, steam turbines, 
 Geared drive, 4 shafts, 144,131 shp / 107,522 Kw = 37.00 kts
 Range 5,400nm at 15.00 kts
 Bunker at max displacement = 1,383 tons

Complement:
 563 - 733

Cost:
 £2.614 million / $10.457 million

Distribution of weights at normal displacement:
 Armament: 308 tons, 2.6 %
    - Guns: 292 tons, 2.5 %
    - Torpedoes: 16 tons, 0.1 %
 Armour: 1,925 tons, 16.4 %
    - Belts: 491 tons, 4.2 %
    - Torpedo bulkhead: 228 tons, 1.9 %
    - Armament: 232 tons, 2.0 %
    - Armour Deck: 941 tons, 8.0 %
    - Conning Tower: 33 tons, 0.3 %
 Machinery: 3,809 tons, 32.4 %
 Hull, fittings & equipment: 4,605 tons, 39.2 %
 Fuel, ammunition & stores: 1,105 tons, 9.4 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   12,227 lbs / 5,546 Kg = 113.2 x 6.0 " / 152 mm shells or 1.6 torpedoes
 Stability (Unstable if below 1.00): 1.11
 Metacentric height 2.7 ft / 0.8 m
 Roll period: 14.8 seconds
 Steadiness - As gun platform (Average = 50 %): 55 %
   - Recoil effect (Restricted arc if above 1.00): 0.39
 Seaboat quality  (Average = 1.00): 1.09

Hull form characteristics:
 Hull has low quarterdeck ,
   an extended bulbous bow and large transom stern
 Block coefficient (normal/deep): 0.525 / 0.532
 Length to Beam Ratio: 10.59 : 1
 'Natural speed' for length: 28.08 kts
 Power going to wave formation at top speed: 63 %
 Trim (Max stability = 0, Max steadiness = 100): 50
 Bow angle (Positive = bow angles forward): 15.00 degrees
 Stern overhang: 0.00 ft / 0.00 m
 Freeboard (% = length of deck as a percentage of waterline length):
    Fore end,  Aft end
    - Forecastle: 25.00 %,  30.00 ft / 9.14 m,  26.00 ft / 7.92 m
    - Forward deck: 15.00 %,  26.00 ft / 7.92 m,  26.00 ft / 7.92 m
    - Aft deck: 30.00 %,  26.00 ft / 7.92 m,  26.00 ft / 7.92 m
    - Quarter deck: 30.00 %,  18.00 ft / 5.49 m,  18.00 ft / 5.49 m
    - Average freeboard:  24.00 ft / 7.32 m

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 175.1 %
  - Above water (accommodation/working, high = better): 218.5 %
 Waterplane Area: 25,263 Square feet or 2,347 Square metres
 Displacement factor (Displacement / loading): 110 %
 Structure weight / hull surface area: 103 lbs/sq ft or 502 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.92
  - Longitudinal: 2.16
  - Overall: 1.00
 Hull space for machinery, storage, compartmentation is cramped
 Room for accommodation and workspaces is excellent

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