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Friday, July 27, 2007

I thought that I would try to do a better version of what I had originally specified at the "My Victorian Navy" blog

I thought that I would like to see if I could design a 23 knot version of the 21 knot British armoured cruiser that can be seen at the "My Victorian Navy" blog. This is a ship with a 6in armour basis, a 2in deck, 4-9.2in/45 and 14-6in QF guns. The design was inspired by the British-built armoured cruisers built for the Japanese navy. This is the Springsharp report:
GB/CA/1902, Great Britain Armoured Cruiser laid down 1902

Displacement:
 13,919 t light; 14,470 t standard; 16,653 t normal; 18,399 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
 (502.00 ft / 495.00 ft) x 75.00 ft x (25.00 / 27.19 ft)
 (153.01 m / 150.88 m) x 22.86 m  x (7.62 / 8.29 m)

Armament:
      4 - 9.20" / 234 mm 45.0 cal guns - 380.00lbs / 172.37kg shells, 120 per gun
   Breech loading guns in turret on barbette mounts, 1902 Model
   2 x Twin mounts on centreline ends, evenly spread
      14 - 6.00" / 152 mm 45.0 cal guns - 100.00lbs / 45.36kg shells, 150 per gun
   Quick firing guns in casemate mounts, 1902 Model
   14 x Single mounts on sides, evenly spread
  8 hull mounts in casemates- Limited use in heavy seas
      Weight of broadside 2,920 lbs / 1,324 kg

Armour:
   - Belts:  Width (max) Length (avg)  Height (avg)
 Main: 6.00" / 152 mm 320.00 ft / 97.54 m 16.00 ft / 4.88 m
 Ends: 4.00" / 102 mm 175.00 ft / 53.34 m 12.00 ft / 3.66 m
   Main Belt covers 99 % of normal length
   Main belt does not fully cover magazines and engineering spaces

   - Torpedo Bulkhead:
  1.00" / 25 mm 320.00 ft / 97.54 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: 4.00" / 102 mm 4.00" / 102 mm  4.00" / 102 mm

   - Protected deck - single deck: 2.00" / 51 mm For and Aft decks
 Forecastle: 2.00" / 51 mm  Quarter deck: 2.00" / 51 mm

   - Conning towers: Forward 6.00" / 152 mm,  Aft 0.00" / 0 mm

Machinery:
 Coal fired boilers, complex reciprocating steam engines, 
 Direct drive, 2 shafts, 36,801 ihp / 27,453 Kw = 23.00 kts
 Range 5,600nm at 14.00 kts
 Bunker at max displacement = 3,929 tons (100% coal)

Complement:
 732 - 952

Cost:
 £1.487 million / $5.947 million

Distribution of weights at normal displacement:
 Armament: 610 tons, 3.7 %
 Armour: 3,612 tons, 21.7 %
    - Belts: 1,653 tons, 9.9 %
    - Torpedo bulkhead: 296 tons, 1.8 %
    - Armament: 541 tons, 3.2 %
    - Armour Deck: 1,038 tons, 6.2 %
    - Conning Tower: 84 tons, 0.5 %
 Machinery: 5,576 tons, 33.5 %
 Hull, fittings & equipment: 4,121 tons, 24.7 %
 Fuel, ammunition & stores: 2,734 tons, 16.4 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   14,089 lbs / 6,391 Kg = 36.2 x 9.2 " / 234 mm shells or 1.9 torpedoes
 Stability (Unstable if below 1.00): 1.66
 Metacentric height 7.5 ft / 2.3 m
 Roll period: 11.5 seconds
 Steadiness - As gun platform (Average = 50 %): 77 %
   - Recoil effect (Restricted arc if above 1.00): 0.18
 Seaboat quality  (Average = 1.00): 1.53

Hull form characteristics:
 Hull has a flush deck,
   a ram bow and a cruiser stern
 Block coefficient (normal/deep): 0.628 / 0.638
 Length to Beam Ratio: 6.60 : 1
 'Natural speed' for length: 22.25 kts
 Power going to wave formation at top speed: 53 %
 Trim (Max stability = 0, Max steadiness = 100): 50
 Bow angle (Positive = bow angles forward): -3.00 degrees
 Stern overhang: -2.00 ft / -0.61 m
 Freeboard (% = length of deck as a percentage of waterline length):
    Fore end,  Aft end
    - Forecastle: 25.00 %,  24.00 ft / 7.32 m,  21.00 ft / 6.40 m
    - Forward deck: 30.00 %,  21.00 ft / 6.40 m,  19.00 ft / 5.79 m
    - Aft deck: 20.00 %,  19.00 ft / 5.79 m,  19.00 ft / 5.79 m
    - Quarter deck: 25.00 %,  19.00 ft / 5.79 m,  20.00 ft / 6.10 m
    - Average freeboard:  20.23 ft / 6.16 m
 Ship tends to be wet forward

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 165.1 %
  - Above water (accommodation/working, high = better): 142.1 %
 Waterplane Area: 27,869 Square feet or 2,589 Square metres
 Displacement factor (Displacement / loading): 99 %
 Structure weight / hull surface area: 109 lbs/sq ft or 530 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.94
  - Longitudinal: 1.68
  - Overall: 0.99
 Caution: Hull subject to strain in open-sea
 Hull space for machinery, storage, compartmentation is cramped
 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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