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Saturday, June 11, 2005

My new version of the GB/BB/1914 design

My friend Cliff had conceived of an 18inch gun armed battleship to be built in numbers for the British navy in our building program wargame, back in 1971. I compared the originally calculated figures, and they were quite close, except that our hull weight estimate was about half of what Springsharp wants for a ship carrying the guns and armor that we had planned. This is the new Springsharp report:
GB/BB/1914 , Enter country Enter ship type laid down 1914 (Engine 1917)

Displacement:
 53,755 t light; 56,342 t standard; 60,000 t normal; 62,926 t full load

Dimensions: Length overall / water x beam x draught
 801.68 ft / 800.00 ft x 120.00 ft x 33.00 ft (normal load)
 244.35 m / 243.84 m x 36.58 m  x 10.06 m

Armament:
     9 - 18.00" / 457 mm guns (3x3 guns), 2,916.00lbs / 1,322.68kg shells, 1914 Model
   Breech loading guns in turrets (on barbettes)
   on centreline ends, majority forward, 1 raised mount - superfiring
     20 - 5.00" / 127 mm guns (10x2 guns), 62.50lbs / 28.35kg shells, 1914 Model
   Quick firing guns in turrets (on barbettes)
   on side, all amidships, 4 raised mounts - superfiring
 Weight of broadside 27,494 lbs / 12,471 kg
 Shells per gun, main battery: 90

Armour:
  - Belts:  Width (max) Length (avg)  Height (avg)
 Main: 18.0" / 457 mm 450.00 ft / 137.16 m 16.00 ft / 4.88 m
 Ends: Unarmoured
   Main Belt covers 87 % of normal length

  - Torpedo Bulkhead:
  3.00" / 76 mm 450.00 ft / 137.16 m 29.00 ft / 8.84 m

  - Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
 Main: 18.0" / 457 mm 9.00" / 229 mm  18.0" / 457 mm
 2nd: 4.00" / 102 mm 3.00" / 76 mm  4.00" / 102 mm

  - Armour deck: 7.00" / 178 mm, Conning tower: 18.00" / 457 mm

Machinery:
 Oil fired boilers, steam turbines,
 Geared drive, 4 shafts, 97,562 shp / 72,781 Kw = 25.00 kts
 Range 7,500nm at 15.00 kts
 Bunker at max displacement = 6,585 tons

Complement:
 1,916 - 2,491

Cost:
 £6.706 million / $26.824 million

Distribution of weights at normal displacement:
 Armament: 3,437 tons, 5.7 %
 Armour: 23,376 tons, 39.0 %
    - Belts: 5,856 tons, 9.8 %
    - Torpedo bulkhead: 1,449 tons, 2.4 %
    - Armament: 5,841 tons, 9.7 %
    - Armour Deck: 9,636 tons, 16.1 %
    - Conning Tower: 594 tons, 1.0 %
 Machinery: 3,576 tons, 6.0 %
 Hull, fittings & equipment: 23,366 tons, 38.9 %
 Fuel, ammunition & stores: 6,245 tons, 10.4 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   94,691 lbs / 42,951 Kg = 32.5 x 18.0 " / 457 mm shells or 15.9 torpedoes
 Stability (Unstable if below 1.00): 1.10
 Metacentric height 7.9 ft / 2.4 m
 Roll period: 18.0 seconds
 Steadiness - As gun platform (Average = 50 %): 75 %
   - Recoil effect (Restricted arc if above 1.00): 0.77
 Seaboat quality  (Average = 1.00): 1.50

Hull form characteristics:
 Hull has a flush deck
 Block coefficient: 0.663
 Length to Beam Ratio: 6.67 : 1
 'Natural speed' for length: 28.28 kts
 Power going to wave formation at top speed: 45 %
 Trim (Max stability = 0, Max steadiness = 100): 50
 Bow angle (Positive = bow angles forward): 3.00 degrees
 Stern overhang: 0.00 ft / 0.00 m
 Freeboard (% = measuring location as a percentage of overall length):
    - Stem:  32.00 ft / 9.75 m
    - Forecastle (20 %): 25.00 ft / 7.62 m
    - Mid (50 %):  25.00 ft / 7.62 m
    - Quarterdeck (15 %): 25.00 ft / 7.62 m
    - Stern:  25.00 ft / 7.62 m
    - Average freeboard: 25.56 ft / 7.79 m

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 75.1 %
  - Above water (accommodation/working, high = better): 184.9 %
 Waterplane Area: 74,412 Square feet or 6,913 Square metres
 Displacement factor (Displacement / loading): 103 %
 Structure weight / hull surface area: 234 lbs/sq ft or 1,142 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.96
  - Longitudinal: 1.39
  - 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
 Excellent seaboat, comfortable, can fire her guns in the heaviest weather

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