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Tuesday, July 03, 2007

A faster French armoured cruiser

I decided that I would see if I could achieve a higher speed for my French fast armoured cruiser design. I was able to reach 36 knots with the ship by changing the shape and reducing protection. This is the Springsharp report:
F/CA/1917 Fast, France Armoured Cruiser laid down 1917 (Engine 1937)

Displacement:
 16,817 t light; 17,602 t standard; 18,643 t normal; 19,477 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
 (751.80 ft / 742.00 ft) x 71.00 ft x (22.00 / 22.78 ft)
 (229.15 m / 226.16 m) x 21.64 m  x (6.71 / 6.94 m)

Armament:
      8 - 9.40" / 239 mm 55.0 cal guns - 449.00lbs / 203.66kg shells, 150 per gun
   Breech loading guns in turret on barbette mounts, 1917 Model
   2 x Quad mounts on centreline, forward deck forward
  1 raised mount - superfiring
      12 - 5.50" / 140 mm 55.0 cal guns - 90.00lbs / 40.82kg shells, 150 per gun
   Quick firing guns in turret on barbette mounts, 1917 Model
   4 x Triple mounts on sides, aft deck forward
      8 - 3.40" / 86.4 mm 50.0 cal guns - 20.80lbs / 9.43kg shells, 150 per gun
   Anti-air guns in deck and hoist mounts, 1917 Model
   4 x Twin mounts on sides, aft deck aft
  4 raised mounts
      Weight of broadside 4,838 lbs / 2,195 kg
      6 - 21.3" / 540 mm, 22.00 ft / 6.71 m torpedoes - 1.440 t each, 8.642 t total
 In 2 sets of deck mounted carriage/fixed tubes

Armour:
   - Belts:  Width (max) Length (avg)  Height (avg)
 Main: 5.00" / 127 mm 480.00 ft / 146.30 m 12.00 ft / 3.66 m
 Ends: Unarmoured
   Main Belt covers 100 % of normal length
   Main belt does not fully cover magazines and engineering spaces

   - Torpedo Bulkhead:
  1.00" / 25 mm 480.00 ft / 146.30 m 22.00 ft / 6.71 m

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

   - Box over magazines: 3.00" / 76 mm

   - Conning towers: Forward 6.00" / 152 mm,  Aft 0.00" / 0 mm

Machinery:
 Oil fired boilers, steam turbines, 
 Geared drive, 4 shafts, 186,710 shp / 139,286 Kw = 36.00 kts
 Range 5,600nm at 15.00 kts
 Bunker at max displacement = 1,875 tons

Complement:
 797 - 1,037

Cost:
 £3.393 million / $13.573 million

Distribution of weights at normal displacement:
 Armament: 1,328 tons, 7.1 %
    - Guns: 1,320 tons, 7.1 %
    - Torpedoes: 9 tons, 0.0 %
 Armour: 2,452 tons, 13.2 %
    - Belts: 1,179 tons, 6.3 %
    - Torpedo bulkhead: 391 tons, 2.1 %
    - Armament: 675 tons, 3.6 %
    - Armour Deck: 117 tons, 0.6 %
    - Conning Tower: 91 tons, 0.5 %
 Machinery: 5,175 tons, 27.8 %
 Hull, fittings & equipment: 7,862 tons, 42.2 %
 Fuel, ammunition & stores: 1,826 tons, 9.8 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   17,081 lbs / 7,748 Kg = 41.1 x 9.4 " / 239 mm shells or 2.1 torpedoes
 Stability (Unstable if below 1.00): 1.07
 Metacentric height 3.4 ft / 1.0 m
 Roll period: 16.2 seconds
 Steadiness - As gun platform (Average = 50 %): 54 %
   - Recoil effect (Restricted arc if above 1.00): 0.85
 Seaboat quality  (Average = 1.00): 1.09

Hull form characteristics:
 Hull has rise forward of midbreak,
   an extended bulbous bow and a cruiser stern
 Block coefficient (normal/deep): 0.563 / 0.568
 Length to Beam Ratio: 10.45 : 1
 'Natural speed' for length: 27.24 kts
 Power going to wave formation at top speed: 58 %
 Trim (Max stability = 0, Max steadiness = 100): 50
 Bow angle (Positive = bow angles forward): 12.00 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 %,  32.00 ft / 9.75 m,  28.00 ft / 8.53 m
    - Forward deck: 36.00 %,  28.00 ft / 8.53 m,  28.00 ft / 8.53 m
    - Aft deck: 21.00 %,  20.00 ft / 6.10 m,  20.00 ft / 6.10 m
    - Quarter deck: 16.00 %,  20.00 ft / 6.10 m,  20.00 ft / 6.10 m
    - Average freeboard:  25.47 ft / 7.76 m

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 163.0 %
  - Above water (accommodation/working, high = better): 221.4 %
 Waterplane Area: 37,217 Square feet or 3,458 Square metres
 Displacement factor (Displacement / loading): 103 %
 Structure weight / hull surface area: 141 lbs/sq ft or 689 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.96
  - Longitudinal: 1.43
  - Overall: 1.00
 Hull space for machinery, storage, compartmentation is cramped
 Room for accommodation and workspaces is excellent

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