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Sunday, January 22, 2006

The US/CA/1916 design

To obtain a reasonable design for the US/CA/1916, lightweight, high-power machinery was required. In some ways, the design is still not satisfactory, as the speed is just 31 knots. For the time, 31 knots was not unreasonable, but at least 32 knots would be better. This design is probably better protected than the real ships built at this date, and later. If I had been willing to accept less protection, I might have been able to reach 32 or 33 knots. The armament is now 8-8in in twin turrets. This is the Springsharp report:
US/CA/1916, United States Heavy Cruiser laid down 1916 (Engine 1927)

Displacement:
 10,505 t light; 10,900 t standard; 12,400 t normal; 13,600 t full load

Dimensions: Length overall / water x beam x draught
 598.47 ft / 595.00 ft x 60.00 ft x 22.00 ft (normal load)
 182.41 m / 181.36 m x 18.29 m  x 6.71 m

Armament:
      8 - 8.00" / 203 mm guns (4x2 guns), 256.00lbs / 116.12kg shells, 1916 Model
   Breech loading guns in turrets (on barbettes)
   on centreline ends, evenly spread, 2 raised mounts - superfiring
      4 - 4.00" / 102 mm guns in single mounts, 32.00lbs / 14.51kg shells, 1916 Model
   Anti-aircraft guns in deck mounts with hoists
   on side, all amidships
      12 - 0.50" / 12.7 mm guns in single mounts, 0.06lbs / 0.03kg shells, 1916 Model
   Machine guns in deck mounts 
   on side, all amidships, all raised mounts - superfiring
 Weight of broadside 2,177 lbs / 987 kg
 Shells per gun, main battery: 120
 6 - 21.0" / 533.4 mm above water torpedoes

Armour:
   - Belts:  Width (max) Length (avg)  Height (avg)
 Main: 4.00" / 102 mm 570.00 ft / 173.74 m 15.00 ft / 4.57 m
 Ends: Unarmoured
   Main Belt covers 147 % of normal length

   - Torpedo Bulkhead:
  1.00" / 25 mm 570.00 ft / 173.74 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: 2.00" / 51 mm, Conning tower: 4.00" / 102 mm

Machinery:
 Oil fired boilers, steam turbines, 
 Geared drive, 4 shafts, 86,692 shp / 64,673 Kw = 31.00 kts
 Range 10,000nm at 15.00 kts
 Bunker at max displacement = 2,699 tons

Complement:
 586 - 763

Cost:
 £1.603 million / $6.410 million

Distribution of weights at normal displacement:
 Armament: 272 tons, 2.2 %
 Armour: 3,015 tons, 24.3 %
    - Belts: 1,340 tons, 10.8 %
    - Torpedo bulkhead: 443 tons, 3.6 %
    - Armament: 262 tons, 2.1 %
    - Armour Deck: 924 tons, 7.5 %
    - Conning Tower: 46 tons, 0.4 %
 Machinery: 2,737 tons, 22.1 %
 Hull, fittings & equipment: 4,481 tons, 36.1 %
 Fuel, ammunition & stores: 1,895 tons, 15.3 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   16,942 lbs / 7,685 Kg = 66.2 x 8.0 " / 203 mm shells or 2.4 torpedoes
 Stability (Unstable if below 1.00): 1.20
 Metacentric height 3.3 ft / 1.0 m
 Roll period: 13.9 seconds
 Steadiness - As gun platform (Average = 50 %): 59 %
   - Recoil effect (Restricted arc if above 1.00): 0.59
 Seaboat quality  (Average = 1.00): 1.19

Hull form characteristics:
 Hull has rise forward of midbreak
 Block coefficient: 0.553
 Length to Beam Ratio: 9.92 : 1
 'Natural speed' for length: 24.39 kts
 Power going to wave formation at top speed: 56 %
 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:  28.00 ft / 8.53 m
    - Forecastle (20 %): 23.00 ft / 7.01 m
    - Mid (67 %):  23.00 ft / 7.01 m (16.00 ft / 4.88 m aft of break)
    - Quarterdeck (15 %): 16.00 ft / 4.88 m
    - Stern:  16.00 ft / 4.88 m
    - Average freeboard: 21.09 ft / 6.43 m

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 133.1 %
  - Above water (accommodation/working, high = better): 151.2 %
 Waterplane Area: 24,975 Square feet or 2,320 Square metres
 Displacement factor (Displacement / loading): 116 %
 Structure weight / hull surface area: 107 lbs/sq ft or 525 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.96
  - Longitudinal: 1.48
  - Overall: 1.00
 Hull space for machinery, storage, compartmentation is cramped
 Room for accommodation and workspaces is excellent

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