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Monday, October 31, 2005

How about a fast 1906 Armoured Cruiser?

I thought that a fast 1906 armoured cruiser might be a way to better explore the ship design space. This is a 27-knot ship with 7in side armour and 8-9.2in guns. I lapsed back into my usual mode, so the ends are unarmoured and the side armour is a uniform 7in, 17ft high. I increased the length over my initial 545ft to 565ft. I am assuming that the main armament is in echelon, as sort of Indefatigable-like arrangement. I would think that there would be an 8-gun broadside possible, at least on some bearings. This is the Springsharp report:
GB/CA/1906, Great Britain Armoured Cruiser laid down 1906

Displacement:
 14,600 t light; 15,186 t standard; 16,800 t normal; 18,091 t full load

Dimensions: Length overall / water x beam x draught
 565.00 ft / 565.00 ft x 78.00 ft x 24.00 ft (normal load)
 172.21 m / 172.21 m x 23.77 m  x 7.32 m

Armament:
      8 - 9.20" / 234 mm guns (4x2 guns), 389.34lbs / 176.60kg shells, 1906 Model
   Breech loading guns in turrets (on barbettes)
   on centreline ends, evenly spread
      16 - 4.00" / 102 mm guns in single mounts, 32.00lbs / 14.51kg shells, 1906 Model
   Quick firing guns in casemate mounts 
   on side, evenly spread, 4 raised mounts
 Weight of broadside 3,627 lbs / 1,645 kg
 Shells per gun, main battery: 120
 4 - 21.0" / 533.4 mm above water torpedoes

Armour:
   - Belts:  Width (max) Length (avg)  Height (avg)
 Main: 7.00" / 178 mm 370.00 ft / 112.78 m 17.00 ft / 5.18 m
 Ends: Unarmoured
   Main Belt covers 101 % of normal length
   Main belt does not fully cover magazines and engineering spaces

   - Torpedo Bulkhead:
  1.00" / 25 mm 370.00 ft / 112.78 m 23.00 ft / 7.01 m

   - Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
 Main: 7.00" / 178 mm 4.00" / 102 mm  7.00" / 178 mm
 2nd: 4.00" / 102 mm 4.00" / 102 mm  4.00" / 102 mm

   - Armour deck: 2.00" / 51 mm, Conning tower: 7.00" / 178 mm

Machinery:
 Oil fired boilers, steam turbines, 
 Direct drive, 4 shafts, 64,156 shp / 47,860 Kw = 27.00 kts
 Range 4,400nm at 15.00 kts
 Bunker at max displacement = 2,904 tons

Complement:
 737 - 959

Cost:
 £1.475 million / $5.900 million

Distribution of weights at normal displacement:
 Armament: 453 tons, 2.7 %
 Armour: 4,358 tons, 25.9 %
    - Belts: 1,893 tons, 11.3 %
    - Torpedo bulkhead: 315 tons, 1.9 %
    - Armament: 907 tons, 5.4 %
    - Armour Deck: 1,144 tons, 6.8 %
    - Conning Tower: 99 tons, 0.6 %
 Machinery: 4,166 tons, 24.8 %
 Hull, fittings & equipment: 5,623 tons, 33.5 %
 Fuel, ammunition & stores: 2,200 tons, 13.1 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   19,774 lbs / 8,969 Kg = 50.8 x 9.2 " / 234 mm shells or 2.6 torpedoes
 Stability (Unstable if below 1.00): 1.33
 Metacentric height 5.7 ft / 1.7 m
 Roll period: 13.7 seconds
 Steadiness - As gun platform (Average = 50 %): 63 %
   - Recoil effect (Restricted arc if above 1.00): 0.30
 Seaboat quality  (Average = 1.00): 1.26

Hull form characteristics:
 Hull has rise forward of midbreak
 Block coefficient: 0.556
 Length to Beam Ratio: 7.24 : 1
 'Natural speed' for length: 23.77 kts
 Power going to wave formation at top speed: 55 %
 Trim (Max stability = 0, Max steadiness = 100): 50
 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 %): 23.00 ft / 7.01 m
    - Mid (67 %):  23.00 ft / 7.01 m (15.00 ft / 4.57 m aft of break)
    - Quarterdeck (15 %): 15.00 ft / 4.57 m
    - Stern:  15.00 ft / 4.57 m
    - Average freeboard: 20.60 ft / 6.28 m
 Ship tends to be wet forward

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 136.1 %
  - Above water (accommodation/working, high = better): 155.7 %
 Waterplane Area: 30,928 Square feet or 2,873 Square metres
 Displacement factor (Displacement / loading): 103 %
 Structure weight / hull surface area: 124 lbs/sq ft or 604 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.96
  - Longitudinal: 1.49
  - Overall: 1.00
 Hull space for machinery, storage, compartmentation is cramped
 Room for accommodation and workspaces is excellent
 Good seaboat, rides out heavy weather easily

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