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Tuesday, November 06, 2007

A very large American battleship: the US/BB/1942 Large

I have long toyed with the idea of extremely large battleships. This one is intended to be American and to be laid down in 1942. I kept the draft down to 36ft. If you can believe it, this is a battleship with 51,700 tons of protection! The speed is 30 knots and the armament is 9-21in/45 BLR, 24-5.1in/55 DP, and 56-40mm AA guns. The belt is 18in, inclined by 17 degrees and the deck and torpedo protection are both 8in. The underwater protection is very great, although the protection against gunfire is lighter. If Springsharp would allow it, I would give such a ship 9-24in guns. This is the Springsharp report:
US/BB/1942 Large, United States Battleship laid down 1942 (Engine 1950)

Displacement:
 115,064 t light; 120,858 t standard; 130,615 t normal; 138,421 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
 (1,198.29 ft / 1,180.00 ft) x 152.00 ft x (36.00 / 37.89 ft)
 (365.24 m / 359.66 m) x 46.33 m  x (10.97 / 11.55 m)

Armament:
      9 - 21.00" / 533 mm 45.0 cal guns - 5,000.00lbs / 2,267.96kg shells, 120 per gun
   Breech loading guns in turret on barbette mounts, 1942 Model
   3 x Triple mounts on centreline ends, majority forward
  1 raised mount - superfiring
      24 - 5.10" / 130 mm 55.0 cal guns - 71.59lbs / 32.47kg shells, 180 per gun
   Dual purpose guns in turret on barbette mounts, 1942 Model
   12 x Twin mounts on sides, forward deck aft
  4 raised mounts - superfiring
      56 - 1.57" / 40.0 mm 60.0 cal guns - 2.00lbs / 0.91kg shells, 150 per gun
   Breech loading guns in deck mounts, 1942 Model
   14 x Quad mounts on sides amidships
  8 raised mounts
      Weight of broadside 46,830 lbs / 21,242 kg

Armour:
   - Belts:  Width (max) Length (avg)  Height (avg)
 Main: 18.0" / 457 mm 760.00 ft / 231.65 m 17.00 ft / 5.18 m
 Ends: Unarmoured
   Main Belt covers 99 % of normal length

   - Torpedo Bulkhead:
  8.00" / 203 mm 760.00 ft / 231.65 m 36.00 ft / 10.97 m

   - Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
 Main: 21.0" / 533 mm 14.0" / 356 mm  21.0" / 533 mm
 2nd: 5.00" / 127 mm 4.00" / 102 mm  5.00" / 127 mm

   - Armoured deck - multiple decks: 8.00" / 203 mm For and Aft decks
 Forecastle: 8.00" / 203 mm  Quarter deck: 8.00" / 203 mm

   - Conning towers: Forward 21.00" / 533 mm,  Aft 0.00" / 0 mm

Machinery:
 Oil fired boilers, steam turbines, 
 Geared drive, 4 shafts, 287,107 shp / 214,182 Kw = 30.00 kts
 Range 12,000nm at 18.00 kts
 Bunker at max displacement = 17,563 tons

Complement:
 3,434 - 4,465

Cost:
 £57.993 million / $231.971 million

Distribution of weights at normal displacement:
 Armament: 6,582 tons, 5.0 %
 Armour: 51,700 tons, 39.6 %
    - Belts: 10,015 tons, 7.7 %
    - Torpedo bulkhead: 8,099 tons, 6.2 %
    - Armament: 10,820 tons, 8.3 %
    - Armour Deck: 21,602 tons, 16.5 %
    - Conning Tower: 1,165 tons, 0.9 %
 Machinery: 6,869 tons, 5.3 %
 Hull, fittings & equipment: 49,914 tons, 38.2 %
 Fuel, ammunition & stores: 15,551 tons, 11.9 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   314,603 lbs / 142,702 Kg = 67.9 x 21.0 " / 533 mm shells or 95.0 torpedoes
 Stability (Unstable if below 1.00): 1.24
 Metacentric height 13.9 ft / 4.2 m
 Roll period: 17.1 seconds
 Steadiness - As gun platform (Average = 50 %): 74 %
   - Recoil effect (Restricted arc if above 1.00): 0.58
 Seaboat quality  (Average = 1.00): 1.48

Hull form characteristics:
 Hull has a flush deck,
   an extended bulbous bow and a cruiser stern
 Block coefficient (normal/deep): 0.708 / 0.713
 Length to Beam Ratio: 7.76 : 1
 'Natural speed' for length: 34.35 kts
 Power going to wave formation at top speed: 43 %
 Trim (Max stability = 0, Max steadiness = 100): 50
 Bow angle (Positive = bow angles forward): 20.00 degrees
 Stern overhang: 3.00 ft / 0.91 m
 Freeboard (% = length of deck as a percentage of waterline length):
    Fore end,  Aft end
    - Forecastle: 20.00 %,  42.00 ft / 12.80 m,  35.00 ft / 10.67 m
    - Forward deck: 30.00 %,  35.00 ft / 10.67 m,  32.00 ft / 9.75 m
    - Aft deck: 35.00 %,  32.00 ft / 9.75 m,  32.00 ft / 9.75 m
    - Quarter deck: 15.00 %,  32.00 ft / 9.75 m,  32.00 ft / 9.75 m
    - Average freeboard:  33.61 ft / 10.24 m

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 54.2 %
  - Above water (accommodation/working, high = better): 262.6 %
 Waterplane Area: 144,788 Square feet or 13,451 Square metres
 Displacement factor (Displacement / loading): 125 %
 Structure weight / hull surface area: 273 lbs/sq ft or 1,333 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 1.00
  - Longitudinal: 1.01
  - Overall: 1.00
 Hull space for machinery, storage, compartmentation is excellent
 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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