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Friday, July 07, 2006

The GB/BB/1915 45,000 tons battleship design

My friend Cliff had toyed with the idea of battleships with 12-16in guns and battlecruisers with 8-15in guns for a 1915 building program. The battleship design was easily done with Springsharp. The Standard displacment ended up as 45,848 tons. This is the Springsharp report:
GB/BB/1915 45,000 tons, Great Britain Battleship laid down 1915 (Engine 1927)

Displacement:
 43,574 t light; 45,848 t standard; 48,500 t normal; 50,621 t full load

Dimensions: Length overall / water x beam x draught
 702.03 ft / 700.00 ft x 110.00 ft x 36.00 ft (normal load)
 213.98 m / 213.36 m x 33.53 m  x 10.97 m

Armament:
      12 - 16.00" / 406 mm guns (4x3 guns), 2,048.00lbs / 928.96kg shells, 1915 Model
   Breech loading guns in turrets (on barbettes)
   on centreline ends, evenly spread, 2 raised mounts - superfiring
   Main guns limited to end-on fire
      20 - 5.00" / 127 mm guns (10x2 guns), 62.50lbs / 28.35kg shells, 1915 Model
   Quick firing guns in turrets (on barbettes)
   on side, all amidships, 6 raised mounts - superfiring
 Weight of broadside 25,826 lbs / 11,714 kg
 Shells per gun, main battery: 90

Armour:
   - Belts:  Width (max) Length (avg)  Height (avg)
 Main: 16.0" / 406 mm 385.00 ft / 117.35 m 17.00 ft / 5.18 m
 Ends: Unarmoured
   Main Belt covers 85 % of normal length

   - Torpedo Bulkhead:
  4.00" / 102 mm 385.00 ft / 117.35 m 36.00 ft / 10.97 m

   - Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
 Main: 16.0" / 406 mm 10.0" / 254 mm  16.0" / 406 mm
 2nd: 5.00" / 127 mm 5.00" / 127 mm  5.00" / 127 mm

   - Armour deck: 6.00" / 152 mm, Conning tower: 16.00" / 406 mm

Machinery:
 Oil fired boilers, steam turbines, 
 Geared drive, 4 shafts, 53,395 shp / 39,832 Kw = 22.00 kts
 Range 7,500nm at 15.00 kts
 Bunker at max displacement = 4,773 tons

Complement:
 1,633 - 2,124

Cost:
 £6.506 million / $26.024 million

Distribution of weights at normal displacement:
 Armament: 3,228 tons, 6.7 %
 Armour: 19,868 tons, 41.0 %
    - Belts: 4,777 tons, 9.8 %
    - Torpedo bulkhead: 2,051 tons, 4.2 %
    - Armament: 6,258 tons, 12.9 %
    - Armour Deck: 6,324 tons, 13.0 %
    - Conning Tower: 458 tons, 0.9 %
 Machinery: 1,685 tons, 3.5 %
 Hull, fittings & equipment: 18,793 tons, 38.7 %
 Fuel, ammunition & stores: 4,926 tons, 10.2 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   57,990 lbs / 26,304 Kg = 28.3 x 16.0 " / 406 mm shells or 9.7 torpedoes
 Stability (Unstable if below 1.00): 0.95
 Metacentric height 5.2 ft / 1.6 m
 Roll period: 20.2 seconds
 Steadiness - As gun platform (Average = 50 %): 75 %
   - Recoil effect (Restricted arc if above 1.00): 1.12
 Seaboat quality  (Average = 1.00): 1.51

Hull form characteristics:
 Hull has a flush deck
 Block coefficient: 0.612
 Length to Beam Ratio: 6.36 : 1
 'Natural speed' for length: 26.46 kts
 Power going to wave formation at top speed: 42 %
 Trim (Max stability = 0, Max steadiness = 100): 50
 Bow angle (Positive = bow angles forward): 4.00 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 %): 23.00 ft / 7.01 m
    - Mid (50 %):  23.00 ft / 7.01 m
    - Quarterdeck (15 %): 23.00 ft / 7.01 m
    - Stern:  23.00 ft / 7.01 m
    - Average freeboard: 23.48 ft / 7.16 m
 Ship tends to be wet forward

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 75.0 %
  - Above water (accommodation/working, high = better): 152.8 %
 Waterplane Area: 56,970 Square feet or 5,293 Square metres
 Displacement factor (Displacement / loading): 99 %
 Structure weight / hull surface area: 234 lbs/sq ft or 1,143 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.94
  - Longitudinal: 1.72
  - Overall: 1.00
 Caution: Poor stability - excessive risk of capsizing
 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
 Excellent seaboat, comfortable, can fire her guns in the heaviest weather

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