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Monday, January 14, 2008

A big British dreadnought cruiser: the GB/CB/1905

This is the cruiser variant of the battleship-cruiser design. The side armour is thinner and the speed is raised to 26 knots. The armament is 8-12in/45 on the centerline, with a super-firing turret aft. The secondary armament is the same 16-4in QF guns in casemates. The belt is 10in on the waterline. The design depends on lightweight machinery. This is the Springsharp report:
GB/BB/1905, Great Britain Dreadnought Cruiser laid down 1905 (Engine 1917)

Displacement:
 20,213 t light; 21,073 t standard; 23,413 t normal; 25,286 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
 (625.00 ft / 618.00 ft) x 85.00 ft x (26.00 / 27.71 ft)
 (190.50 m / 188.37 m) x 25.91 m  x (7.92 / 8.44 m)

Armament:
      8 - 12.00" / 305 mm 45.0 cal guns - 871.37lbs / 395.24kg shells, 90 per gun
   Breech loading guns in turret on barbette mounts, 1905 Model
   3 x Twin mounts on centreline ends, evenly spread
  1 raised mount aft - superfiring
   1 x Twin mount on centreline, forward deck aft
      16 - 4.00" / 102 mm 45.0 cal guns - 32.27lbs / 14.64kg shells, 150 per gun
   Quick firing guns in casemate mounts, 1905 Model
   16 x Single mounts on sides, evenly spread
  8 raised mounts
      Weight of broadside 7,487 lbs / 3,396 kg

Armour:
   - Belts:  Width (max) Length (avg)  Height (avg)
 Main: 10.0" / 254 mm 405.00 ft / 123.44 m 9.00 ft / 2.74 m
 Ends: 4.00" / 102 mm 170.00 ft / 51.82 m 12.00 ft / 3.66 m
   43.00 ft / 13.11 m Unarmoured ends
 Upper: 7.00" / 178 mm 405.00 ft / 123.44 m 8.00 ft / 2.44 m
   Main Belt covers 101 % of normal length

   - Torpedo Bulkhead:
  2.00" / 51 mm 395.00 ft / 120.40 m 26.00 ft / 7.92 m

   - Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
 Main: 10.0" / 254 mm 7.00" / 178 mm  10.0" / 254 mm
 2nd: 4.00" / 102 mm 4.00" / 102 mm  4.00" / 102 mm

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

   - Conning towers: Forward 10.00" / 254 mm,  Aft 0.00" / 0 mm

Machinery:
 Coal fired boilers, steam turbines, 
 Direct drive, 4 shafts, 66,702 shp / 49,760 Kw = 26.00 kts
 Range 5,400nm at 16.00 kts
 Bunker at max displacement = 4,213 tons (100% coal)

Complement:
 946 - 1,230

Cost:
 £1.760 million / $7.039 million

Distribution of weights at normal displacement:
 Armament: 1,331 tons, 5.7 %
 Armour: 7,921 tons, 33.8 %
    - Belts: 2,836 tons, 12.1 %
    - Torpedo bulkhead: 760 tons, 3.2 %
    - Armament: 2,004 tons, 8.6 %
    - Armour Deck: 2,145 tons, 9.2 %
    - Conning Tower: 176 tons, 0.8 %
 Machinery: 2,690 tons, 11.5 %
 Hull, fittings & equipment: 8,271 tons, 35.3 %
 Fuel, ammunition & stores: 3,200 tons, 13.7 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   43,692 lbs / 19,818 Kg = 50.6 x 12.0 " / 305 mm shells or 6.9 torpedoes
 Stability (Unstable if below 1.00): 1.16
 Metacentric height 5.2 ft / 1.6 m
 Roll period: 15.7 seconds
 Steadiness - As gun platform (Average = 50 %): 71 %
   - Recoil effect (Restricted arc if above 1.00): 0.72
 Seaboat quality  (Average = 1.00): 1.41

Hull form characteristics:
 Hull has low quarterdeck ,
   a ram bow and a cruiser stern
 Block coefficient (normal/deep): 0.600 / 0.608
 Length to Beam Ratio: 7.27 : 1
 'Natural speed' for length: 24.86 kts
 Power going to wave formation at top speed: 52 %
 Trim (Max stability = 0, Max steadiness = 100): 50
 Bow angle (Positive = bow angles forward): -3.00 degrees
 Stern overhang: -3.00 ft / -0.91 m
 Freeboard (% = length of deck as a percentage of waterline length):
    Fore end,  Aft end
    - Forecastle: 27.00 %,  28.00 ft / 8.53 m,  26.00 ft / 7.92 m
    - Forward deck: 30.00 %,  26.00 ft / 7.92 m,  26.00 ft / 7.92 m
    - Aft deck: 10.00 %,  26.00 ft / 7.92 m,  26.00 ft / 7.92 m
    - Quarter deck: 33.00 %,  18.00 ft / 5.49 m,  18.00 ft / 5.49 m
    - Average freeboard:  23.58 ft / 7.19 m

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 83.6 %
  - Above water (accommodation/working, high = better): 201.1 %
 Waterplane Area: 38,420 Square feet or 3,569 Square metres
 Displacement factor (Displacement / loading): 119 %
 Structure weight / hull surface area: 156 lbs/sq ft or 761 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.95
  - Longitudinal: 1.64
  - Overall: 1.00
 Hull space for machinery, storage, compartmentation is adequate
 Room for accommodation and workspaces is excellent
 Ship has slow, easy roll, a good, steady gun platform
 Good seaboat, rides out heavy weather easily

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