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Thursday, January 26, 2006

The US/CA/1927 design

The improvements incorporated in the US/CA/1927 design are a 34 knot speed and 3in deck armour. The hull is rather blocky, as to maximize strength, the dimensions have been kept compact for the 17,000 ton normal displacement. The draft did not change, but it is rather deep at 24 knots. The advantage is Springsharp is that a deeper draft increases hull strength and seakeeping. This is the Springsharp report:
US/CA/1927, United States Heavy Cruiser laid down 1927 (Engine 1939)

Displacement:
 14,782 t light; 15,367 t standard; 17,000 t normal; 18,307 t full load

Dimensions: Length overall / water x beam x draught
 659.54 ft / 655.00 ft x 64.00 ft x 24.00 ft (normal load)
 201.03 m / 199.64 m x 19.51 m  x 7.32 m

Armament:
      12 - 8.00" / 203 mm guns (4 mounts), 256.00lbs / 116.12kg shells, 1927 Model
   Breech loading guns in turrets (on barbettes)
   on centreline ends, evenly spread, 4 raised guns - superfiring
      8 - 5.00" / 127 mm guns in single mounts, 62.50lbs / 28.35kg shells, 1927 Model
   Anti-aircraft guns in deck mounts with hoists
   on side, all amidships
      16 - 0.50" / 12.7 mm guns in single mounts, 0.06lbs / 0.03kg shells, 1927 Model
   Machine guns in deck mounts 
   on side, all amidships, all raised mounts - superfiring
 Weight of broadside 3,573 lbs / 1,621 kg
 Shells per gun, main battery: 120
 8 - 21.0" / 533.4 mm above water torpedoes

Armour:
   - Belts:  Width (max) Length (avg)  Height (avg)
 Main: 4.00" / 102 mm 610.00 ft / 185.93 m 16.00 ft / 4.88 m
 Ends: Unarmoured
   Main Belt covers 143 % of normal length

   - Torpedo Bulkhead:
  1.00" / 25 mm 610.00 ft / 185.93 m 21.00 ft / 6.40 m

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

   - Armour deck: 3.00" / 76 mm, Conning tower: 4.00" / 102 mm

Machinery:
 Oil fired boilers, steam turbines, 
 Geared drive, 4 shafts, 149,277 shp / 111,360 Kw = 34.00 kts
 Range 10,000nm at 15.00 kts
 Bunker at max displacement = 2,940 tons

Complement:
 743 - 967

Cost:
 £5.302 million / $21.207 million

Distribution of weights at normal displacement:
 Armament: 447 tons, 2.6 %
 Armour: 4,102 tons, 24.1 %
    - Belts: 1,542 tons, 9.1 %
    - Torpedo bulkhead: 474 tons, 2.8 %
    - Armament: 341 tons, 2.0 %
    - Armour Deck: 1,688 tons, 9.9 %
    - Conning Tower: 57 tons, 0.3 %
 Machinery: 4,039 tons, 23.8 %
 Hull, fittings & equipment: 6,194 tons, 36.4 %
 Fuel, ammunition & stores: 2,218 tons, 13.0 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   20,944 lbs / 9,500 Kg = 81.8 x 8.0 " / 203 mm shells or 2.5 torpedoes
 Stability (Unstable if below 1.00): 1.18
 Metacentric height 3.5 ft / 1.1 m
 Roll period: 14.4 seconds
 Steadiness - As gun platform (Average = 50 %): 54 %
   - Recoil effect (Restricted arc if above 1.00): 0.76
 Seaboat quality  (Average = 1.00): 1.09

Hull form characteristics:
 Hull has rise forward of midbreak
 Block coefficient: 0.591
 Length to Beam Ratio: 10.23 : 1
 'Natural speed' for length: 25.59 kts
 Power going to wave formation at top speed: 60 %
 Trim (Max stability = 0, Max steadiness = 100): 50
 Bow angle (Positive = bow angles forward): 5.00 degrees
 Stern overhang: 2.00 ft / 0.61 m
 Freeboard (% = measuring location as a percentage of overall length):
    - Stem:  29.00 ft / 8.84 m
    - Forecastle (20 %): 26.00 ft / 7.92 m
    - Mid (67 %):  26.00 ft / 7.92 m (18.00 ft / 5.49 m aft of break)
    - Quarterdeck (15 %): 18.00 ft / 5.49 m
    - Stern:  18.00 ft / 5.49 m
    - Average freeboard: 23.60 ft / 7.19 m

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 141.6 %
  - Above water (accommodation/working, high = better): 161.1 %
 Waterplane Area: 30,414 Square feet or 2,826 Square metres
 Displacement factor (Displacement / loading): 108 %
 Structure weight / hull surface area: 119 lbs/sq ft or 583 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.95
  - Longitudinal: 1.57
  - Overall: 1.00
 Hull space for machinery, storage, compartmentation is cramped
 Room for accommodation and workspaces is excellent

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