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Thursday, June 28, 2007

A faster American light cruiser: US/CL/1921

I was curious to see if I might be able to design an American light cruiser with a higher speed than the 1918 model. I assumed that I would need to increase the dimensions, and that certainly helped. I was able to achieve a 36 knot speed, so that the ship carries 9-6in/55 QF, 8-5in/25 AA, and 16-0.50in MG, along with 6-21in TT. The belt is 3in with a 2in deck. I think that this is at least a good initial offering:
US/CL/1921, United States Light Cruiser laid down 1921 (Engine 1950)

Displacement:
 9,361 t light; 9,691 t standard; 10,311 t normal; 10,807 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
 (649.22 ft / 642.00 ft) x 61.00 ft x (19.00 / 19.67 ft)
 (197.88 m / 195.68 m) x 18.59 m  x (5.79 / 6.00 m)

Armament:
      9 - 6.00" / 152 mm 55.0 cal guns - 116.57lbs / 52.88kg shells, 150 per gun
   Quick firing guns in turret on barbette mounts, 1921 Model
   3 x Single mounts on centreline ends, majority forward
  1 raised mount - superfiring
      6 - 5.00" / 127 mm 25.0 cal guns - 56.77lbs / 25.75kg shells, 150 per gun
   Anti-air guns in deck and hoist mounts, 1921 Model
   6 x Single mounts on sides, aft deck forward
  6 raised mounts
      16 - 0.50" / 12.7 mm 45.0 cal guns - 0.06lbs / 0.03kg shells, 150 per gun
   Anti-air guns in deck mounts, 1921 Model
   8 x Twin mounts on sides, forward deck aft
  8 raised mounts
      Weight of broadside 1,391 lbs / 631 kg
      6 - 21.0" / 533 mm, 20.00 ft / 6.10 m torpedoes - 1.307 t each, 7.841 t total
 In 2 sets of deck mounted side rotating tubes

Armour:
   - Belts:  Width (max) Length (avg)  Height (avg)
 Main: 3.00" / 76 mm 420.00 ft / 128.02 m 12.00 ft / 3.66 m
 Ends: Unarmoured
   Main Belt covers 101 % of normal length
   Main belt does not fully cover magazines and engineering spaces

   - Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
 Main: 4.00" / 102 mm 2.00" / 51 mm  3.00" / 76 mm

   - Protected deck - single deck: 2.00" / 51 mm For and Aft decks

   - Conning towers: Forward 3.00" / 76 mm,  Aft 0.00" / 0 mm

Machinery:
 Oil fired boilers, steam turbines, 
 Geared drive, 4 shafts, 132,335 shp / 98,722 Kw = 36.00 kts
 Range 5,400nm at 15.00 kts
 Bunker at max displacement = 1,116 tons

Complement:
 511 - 665

Cost:
 £2.317 million / $9.269 million

Distribution of weights at normal displacement:
 Armament: 425 tons, 4.1 %
    - Guns: 417 tons, 4.0 %
    - Torpedoes: 8 tons, 0.1 %
 Armour: 1,662 tons, 16.1 %
    - Belts: 616 tons, 6.0 %
    - Armament: 256 tons, 2.5 %
    - Armour Deck: 760 tons, 7.4 %
    - Conning Tower: 31 tons, 0.3 %
 Machinery: 3,166 tons, 30.7 %
 Hull, fittings & equipment: 4,108 tons, 39.8 %
 Fuel, ammunition & stores: 950 tons, 9.2 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   10,567 lbs / 4,793 Kg = 97.8 x 6.0 " / 152 mm shells or 1.4 torpedoes
 Stability (Unstable if below 1.00): 1.16
 Metacentric height 3.2 ft / 1.0 m
 Roll period: 14.4 seconds
 Steadiness - As gun platform (Average = 50 %): 51 %
   - Recoil effect (Restricted arc if above 1.00): 0.32
 Seaboat quality  (Average = 1.00): 1.02

Hull form characteristics:
 Hull has rise forward of midbreak,
   a normal bow and a cruiser stern
 Block coefficient (normal/deep): 0.485 / 0.491
 Length to Beam Ratio: 10.52 : 1
 'Natural speed' for length: 25.34 kts
 Power going to wave formation at top speed: 59 %
 Trim (Max stability = 0, Max steadiness = 100): 50
 Bow angle (Positive = bow angles forward): 8.00 degrees
 Stern overhang: 3.00 ft / 0.91 m
 Freeboard (% = length of deck as a percentage of waterline length):
    Fore end,  Aft end
    - Forecastle: 23.00 %,  30.00 ft / 9.14 m,  26.00 ft / 7.92 m
    - Forward deck: 12.00 %,  26.00 ft / 7.92 m,  26.00 ft / 7.92 m
    - Aft deck: 50.00 %,  18.00 ft / 5.49 m,  18.00 ft / 5.49 m
    - Quarter deck: 15.00 %,  18.00 ft / 5.49 m,  18.00 ft / 5.49 m
    - Average freeboard:  21.17 ft / 6.45 m

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 112.3 %
  - Above water (accommodation/working, high = better): 184.6 %
 Waterplane Area: 25,742 Square feet or 2,392 Square metres
 Displacement factor (Displacement / loading): 111 %
 Structure weight / hull surface area: 104 lbs/sq ft or 508 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.97
  - Longitudinal: 1.33
  - Overall: 1.00
 Hull space for machinery, storage, compartmentation is cramped
 Room for accommodation and workspaces is excellent

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