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Saturday, October 28, 2006

The GB/CA/1913 Design E2

The E2 design study from 1913 is interesting, as an example of a 9.2in gun armoured cruiser with a good speed. There are no dimensions, just a displacement and weights, in the specifcation in D. K. Brown's book, The Grand Fleet (1999). These are the specified weights:
Hull      5500 tons
Armament  1900 tons
Armour    3560 tons
Machinery 2700 tons

This is the Springsharp report:
GB/CA/1913 Design E2, Enter country Enter ship type laid down 1913

Displacement:
 13,603 t light; 14,186 t standard; 17,250 t normal; 19,701 t full load

Dimensions: Length overall / water x beam x draught
 550.00 ft / 550.00 ft x 78.00 ft x 25.00 ft (normal load)
 167.64 m / 167.64 m x 23.77 m  x 7.62 m

Armament:
      4 - 9.20" / 234 mm guns (2x2 guns), 389.34lbs / 176.60kg shells, 1913 Model
   Breech loading guns in turrets (on barbettes)
   on centreline ends, evenly spread
      4 - 9.20" / 234 mm guns (2x2 guns), 389.34lbs / 176.60kg shells, 1913 Model
   Breech loading guns in turrets (on barbettes)
   on side, all amidships
      8 - 6.00" / 152 mm guns in single mounts, 108.00lbs / 48.99kg shells, 1913 Model
   Quick firing guns in casemate mounts 
   on side, evenly spread
   8 guns in hull casemates - Limited use in heavy seas
 Weight of broadside 3,979 lbs / 1,805 kg
 Shells per gun, main battery: 100

Armour:
   - Belts:  Width (max) Length (avg)  Height (avg)
 Main: 6.00" / 152 mm 370.00 ft / 112.78 m 8.00 ft / 2.44 m
 Ends: 3.00" / 76 mm 120.00 ft / 36.58 m 8.00 ft / 2.44 m
   60.00 ft / 18.29 m Unarmoured ends
 Upper: 4.00" / 102 mm 370.00 ft / 112.78 m 8.00 ft / 2.44 m
   Main Belt covers 103 % of normal length
   Main belt does not fully cover magazines and engineering spaces

   - Torpedo Bulkhead:
  1.50" / 38 mm 370.00 ft / 112.78 m 25.00 ft / 7.62 m

   - Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
 Main: 6.00" / 152 mm 4.00" / 102 mm  6.00" / 152 mm
 2nd: 6.00" / 152 mm 4.00" / 102 mm  6.00" / 152 mm
 3rd: 6.00" / 152 mm 6.00" / 152 mm  6.00" / 152 mm

   - Armour deck: 2.00" / 51 mm, Conning tower: 6.00" / 152 mm

Machinery:
 Coal fired boilers, steam turbines, 
 Direct drive, 4 shafts, 76,885 shp / 57,356 Kw = 28.00 kts
 Range 5,500nm at 18.00 kts
 Bunker at max displacement = 5,514 tons (100% coal)

Complement:
 752 - 978

Cost:
 £1.481 million / $5.925 million

Distribution of weights at normal displacement:
 Armament: 497 tons, 2.9 %
 Armour: 3,983 tons, 23.1 %
    - Belts: 1,376 tons, 8.0 %
    - Torpedo bulkhead: 513 tons, 3.0 %
    - Armament: 886 tons, 5.1 %
    - Armour Deck: 1,121 tons, 6.5 %
    - Conning Tower: 86 tons, 0.5 %
 Machinery: 3,314 tons, 19.2 %
 Hull, fittings & equipment: 5,809 tons, 33.7 %
 Fuel, ammunition & stores: 3,647 tons, 21.1 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   24,308 lbs / 11,026 Kg = 62.4 x 9.2 " / 234 mm shells or 3.5 torpedoes
 Stability (Unstable if below 1.00): 1.30
 Metacentric height 5.5 ft / 1.7 m
 Roll period: 14.0 seconds
 Steadiness - As gun platform (Average = 50 %): 64 %
   - Recoil effect (Restricted arc if above 1.00): 0.33
 Seaboat quality  (Average = 1.00): 1.15

Hull form characteristics:
 Hull has rise forward of midbreak
 Block coefficient: 0.563
 Length to Beam Ratio: 7.05 : 1
 'Natural speed' for length: 23.45 kts
 Power going to wave formation at top speed: 58 %
 Trim (Max stability = 0, Max steadiness = 100): 55
 Bow angle (Positive = bow angles forward): -2.00 degrees
 Stern overhang: -2.00 ft / -0.61 m
 Freeboard (% = measuring location as a percentage of overall length):
    - Stem:  26.00 ft / 7.92 m
    - Forecastle (20 %): 24.00 ft / 7.32 m
    - Mid (67 %):  24.00 ft / 7.32 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: 21.52 ft / 6.56 m

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 113.7 %
  - Above water (accommodation/working, high = better): 167.2 %
 Waterplane Area: 30,305 Square feet or 2,815 Square metres
 Displacement factor (Displacement / loading): 118 %
 Structure weight / hull surface area: 128 lbs/sq ft or 626 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.94
  - Longitudinal: 1.78
  - Overall: 1.00
 Hull space for machinery, storage, compartmentation is cramped
 Room for accommodation and workspaces is excellent

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