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Friday, December 09, 2005

A GB/CL/1916 light cruiser design

Continuing this design series, this is my first attempt at a 1916 British light cruiser. The armament is 9-6in QF, 4-3in AA, 12-2pdr AA guns, and 8-21in TT (above water). The armour basis is still 4in with a 2in deck. The maximum speed has risen to 32 knots and the range is 5,400nm at 15 knots. This is the Springsharp report:
GB/CL/1916, Great Britain Light Cruiser laid down 1916

Displacement:
 8,704 t light; 8,992 t standard; 9,900 t normal; 10,626 t full load

Dimensions: Length overall / water x beam x draught
 546.36 ft / 545.00 ft x 55.00 ft x 18.00 ft (normal load)
 166.53 m / 166.12 m x 16.76 m  x 5.49 m

Armament:
      9 - 6.00" / 152 mm guns in single mounts, 108.00lbs / 48.99kg shells, 1916 Model
   Quick firing guns in deck mounts with hoists
   on centreline ends, majority forward, 2 raised mounts - superfiring
      4 - 3.00" / 76.2 mm guns in single mounts, 13.50lbs / 6.12kg shells, 1916 Model
   Anti-aircraft guns in deck mounts with hoists
   on side, all amidships
      12 - 1.57" / 40.0 mm guns (3x4 guns), 2.00lbs / 0.91kg shells, 1916 Model
   Breech loading guns in deck mounts 
   on side ends, majority aft
 Weight of broadside 1,050 lbs / 476 kg
 Shells per gun, main battery: 150
 8 - 21.0" / 533.4 mm above water torpedoes, 21 - 21.0" / 533.4 mm submerged torpedo tubes

Armour:
   - Belts:  Width (max) Length (avg)  Height (avg)
 Main: 4.00" / 102 mm 420.00 ft / 128.02 m 12.00 ft / 3.66 m
 Ends: Unarmoured
   Main Belt covers 119 % of normal length
   Main belt does not fully cover magazines and engineering spaces

   - Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
 Main: 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, 
 Geared drive, 4 shafts, 93,429 shp / 69,698 Kw = 32.00 kts
 Range 5,400nm at 15.00 kts
 Bunker at max displacement = 1,634 tons

Complement:
 496 - 645

Cost:
 £1.476 million / $5.905 million

Distribution of weights at normal displacement:
 Armament: 131 tons, 1.3 %
 Armour: 1,774 tons, 17.9 %
    - Belts: 823 tons, 8.3 %
    - Torpedo bulkhead: 0 tons, 0.0 %
    - Armament: 68 tons, 0.7 %
    - Armour Deck: 844 tons, 8.5 %
    - Conning Tower: 40 tons, 0.4 %
 Machinery: 3,481 tons, 35.2 %
 Hull, fittings & equipment: 3,318 tons, 33.5 %
 Fuel, ammunition & stores: 1,196 tons, 12.1 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   4,353 lbs / 1,974 Kg = 40.3 x 6.0 " / 152 mm shells or 0.7 torpedoes
 Stability (Unstable if below 1.00): 1.34
 Metacentric height 3.4 ft / 1.0 m
 Roll period: 12.5 seconds
 Steadiness - As gun platform (Average = 50 %): 53 %
   - Recoil effect (Restricted arc if above 1.00): 0.31
 Seaboat quality  (Average = 1.00): 1.06

Hull form characteristics:
 Hull has rise forward of midbreak
 Block coefficient: 0.642
 Length to Beam Ratio: 9.91 : 1
 'Natural speed' for length: 23.35 kts
 Power going to wave formation at top speed: 62 %
 Trim (Max stability = 0, Max steadiness = 100): 50
 Bow angle (Positive = bow angles forward): 3.00 degrees
 Stern overhang: -2.00 ft / -0.61 m
 Freeboard (% = measuring location as a percentage of overall length):
    - Stem:  26.00 ft / 7.92 m
    - Forecastle (20 %): 23.00 ft / 7.01 m
    - Mid (67 %):  23.00 ft / 7.01 m (15.00 ft / 4.57 m aft of break)
    - Quarterdeck (15 %): 15.00 ft / 4.57 m
    - Stern:  15.00 ft / 4.57 m
    - Average freeboard: 20.60 ft / 6.28 m

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 176.2 %
  - Above water (accommodation/working, high = better): 148.5 %
 Waterplane Area: 22,799 Square feet or 2,118 Square metres
 Displacement factor (Displacement / loading): 101 %
 Structure weight / hull surface area: 89 lbs/sq ft or 432 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.95
  - Longitudinal: 1.51
  - Overall: 1.00
 Hull space for machinery, storage, compartmentation is cramped
 Room for accommodation and workspaces is excellent

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