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Sunday, July 06, 2008

My attempt at an Italian armoured cruiser: It/CA/1897

I am interested in the Spanish cruiser Cristobal Colon, lost at the Battle of Santiago Bay in 1898. The Cristobal Colon was Italian-built along the lines of a series of armoured cruisers. My It/CA/1897 has 2-10in/45, 14-6in/50 QF, and 10-3in QF guns. The armour basis is 6in and the deck is 2in. The speed is a modest 20 knots. I struggled with the Springsharp 3.0 Beta 3, as I kept having "NaN" (not a number). The problem was that I had missed some settings. Once I had found all the places, then I had a workable design. I had to greatly increase the displacement and lighten the machinery for the power. This is the Springsharp report:
It/CA/1897, Italy Armoured Cruiser laid down 1897 (Engine 1904)

Displacement:
 8,028 t light; 8,405 t standard; 9,073 t normal; 9,608 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
 (354.00 ft / 345.00 ft) x 60.00 ft x (23.00 / 24.16 ft)
 (107.90 m / 105.16 m) x 18.29 m  x (7.01 / 7.36 m)

Armament:
      2 - 10.00" / 254 mm 45.0 cal guns - 504.26lbs / 228.73kg shells, 90 per gun
   Breech loading guns in turret on barbette mounts, 1897 Model
   2 x Single mounts on centreline ends, evenly spread
      14 - 6.00" / 152 mm 50.0 cal guns - 114.33lbs / 51.86kg shells, 150 per gun
   Quick firing guns in casemate mounts, 1897 Model
   10 x Single mounts on sides, evenly spread
  10 hull mounts in casemates- Limited use in all but light seas
   4 x Single mounts layout not set
      10 - 3.00" / 76.2 mm 45.0 cal guns - 13.62lbs / 6.18kg shells, 150 per gun
   Quick firing guns in deck mounts, 1897 Model
   10 x Single mounts on sides, evenly spread
  10 raised mounts
      Weight of broadside 2,745 lbs / 1,245 kg
      Main Torpedoes
      4 - 18.0" / 457 mm, 19.00 ft / 5.79 m torpedoes - 0.618 t each, 2.471 t total
 In 4 sets of deck mounted carriage/fixed tubes

Armour:
   - Belts:  Width (max) Length (avg)  Height (avg)
 Main: 6.00" / 152 mm 200.00 ft / 60.96 m 25.00 ft / 7.62 m
 Ends: 4.50" / 114 mm 145.00 ft / 44.20 m 9.00 ft / 2.74 m
   Main Belt covers 89 % of normal length
   Main belt does not fully cover magazines and engineering spaces

   - Torpedo Bulkhead - Additional damage containing bulkheads:
  1.00" / 25 mm 200.00 ft / 60.96 m 23.00 ft / 7.01 m
 Beam between torpedo bulkheads 43.00 ft / 13.11 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
 3rd: 1.00" / 25 mm       -         -

   - Protected deck - single deck:
 For and Aft decks: 2.00" / 51 mm
 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, 17,193 ihp / 12,826 Kw = 20.00 kts
 Range 3,500nm at 12.00 kts
 Bunker at max displacement = 1,203 tons (100% coal)

Complement:
 464 - 604

Cost:
 £0.820 million / $3.280 million

Distribution of weights at normal displacement:
 Armament: 612 tons, 6.7 %
    - Guns: 609 tons, 6.7 %
    - Weapons: 3 tons, 0.0 %
 Armour: 2,895 tons, 31.9 %
    - Belts: 1,602 tons, 17.7 %
    - Torpedo bulkhead: 170 tons, 1.9 %
    - Armament: 466 tons, 5.1 %
    - Armour Deck: 600 tons, 6.6 %
    - Conning Tower: 56 tons, 0.6 %
 Machinery: 2,528 tons, 27.9 %
 Hull, fittings & equipment: 1,993 tons, 22.0 %
 Fuel, ammunition & stores: 1,045 tons, 11.5 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   8,570 lbs / 3,887 Kg = 17.1 x 10.0 " / 254 mm shells or 3.0 torpedoes
 Stability (Unstable if below 1.00): 1.48
 Metacentric height 4.6 ft / 1.4 m
 Roll period: 11.8 seconds
 Steadiness - As gun platform (Average = 50 %): 71 %
   - Recoil effect (Restricted arc if above 1.00): 0.33
 Seaboat quality  (Average = 1.00): 1.33

Hull form characteristics:
 Hull has a flush deck,
   a ram bow and a cruiser stern
 Block coefficient (normal/deep): 0.667 / 0.672
 Length to Beam Ratio: 5.75 : 1
 'Natural speed' for length: 18.57 kts
 Power going to wave formation at top speed: 59 %
 Trim (Max stability = 0, Max steadiness = 100): 53
 Bow angle (Positive = bow angles forward): -7.00 degrees
 Stern overhang: -3.00 ft / -0.91 m
 Freeboard (% = length of deck as a percentage of waterline length):
    Fore end,  Aft end
    - Forecastle: 20.00 %,  19.00 ft / 5.79 m,  18.00 ft / 5.49 m
    - Forward deck: 30.00 %,  18.00 ft / 5.49 m,  17.00 ft / 5.18 m
    - Aft deck: 30.00 %,  17.00 ft / 5.18 m,  17.00 ft / 5.18 m
    - Quarter deck: 20.00 %,  17.00 ft / 5.18 m,  18.00 ft / 5.49 m
    - Average freeboard:  17.53 ft / 5.34 m
 Ship tends to be wet forward

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 153.3 %
  - Above water (accommodation/working, high = better): 113.2 %
 Waterplane Area: 16,105 Square feet or 1,496 Square metres
 Displacement factor (Displacement / loading): 93 %
 Structure weight / hull surface area: 96 lbs/sq ft or 469 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.90
  - Longitudinal: 2.63
  - Overall: 1.00
 Cramped machinery, storage, compartmentation space
 Adequate accommodation and workspace room
 Ship has slow, easy roll, a good, steady gun platform
 Good seaboat, rides out heavy weather easily

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