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Saturday, October 13, 2007

A fast Italian cruiser design

I wondered what sort of Italian cruiser design that I could make work with Springsharp. My ship is sort of an enlarged Capitani Romani type, in that my ship is flush-decked. My ship, though, is armoured more like one of the earlier ships. By going large, my ship carries 9-6in/55, 8-4in AA, 12-37mm AA guns, and 6-21in TT at 37 knots. This is the Springsharp report:
It/CL/1939, Italy Light Cruiser laid down 1939 (Engine 1950)

Displacement:
 9,533 t light; 9,863 t standard; 10,532 t normal; 11,068 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
 (644.00 ft / 638.00 ft) x 60.00 ft x (18.00 / 18.68 ft)
 (196.29 m / 194.46 m) x 18.29 m  x (5.49 / 5.69 m)

Armament:
      9 - 6.00" / 152 mm 55.0 cal guns - 116.57lbs / 52.88kg shells, 150 per gun
   Quick firing guns in turret on barbette mounts, 1939 Model
   3 x Triple mounts on centreline ends, majority forward
  1 raised mount - superfiring
      8 - 4.00" / 102 mm 55.0 cal guns - 32.00lbs / 14.51kg shells, 150 per gun
   Anti-air guns in deck and hoist mounts, 1939 Model
   4 x Twin mounts on sides, aft deck forward
  4 raised mounts
      12 - 1.46" / 37.0 mm 60.0 cal guns - 1.69lbs / 0.77kg shells, 150 per gun
   Anti-air guns in deck and hoist mounts, 1939 Model
   12 x Single mounts on sides, evenly spread
      Weight of broadside 1,325 lbs / 601 kg
      6 - 21.0" / 533 mm, 22.00 ft / 6.71 m torpedoes - 1.497 t each, 8.983 t total
 In 2 sets of deck mounted carriage/fixed tubes

Armour:
   - Belts:  Width (max) Length (avg)  Height (avg)
 Main: 2.00" / 51 mm 420.00 ft / 128.02 m 12.00 ft / 3.66 m
 Ends: Unarmoured
   Main Belt covers 101 % of normal length
   Main belt does not fully cover magazines and engineering spaces

   - Torpedo Bulkhead:
  0.70" / 18 mm 420.00 ft / 128.02 m 18.00 ft / 5.49 m

   - Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
 Main: 3.00" / 76 mm 2.00" / 51 mm  3.00" / 76 mm
 2nd: 1.00" / 25 mm 1.00" / 25 mm  1.00" / 25 mm

   - Armoured deck - multiple decks: 1.00" / 25 mm For and Aft decks
 Forecastle: 1.00" / 25 mm  Quarter deck: 1.00" / 25 mm

   - Conning towers: Forward 3.00" / 76 mm,  Aft 0.00" / 0 mm

Machinery:
 Oil fired boilers, steam turbines, 
 Geared drive, 4 shafts, 133,798 shp / 99,813 Kw = 37.00 kts
 Range 4,700nm at 16.00 kts
 Bunker at max displacement = 1,205 tons

Complement:
 519 - 675

Cost:
 £5.464 million / $21.858 million

Distribution of weights at normal displacement:
 Armament: 387 tons, 3.7 %
    - Guns: 378 tons, 3.6 %
    - Torpedoes: 9 tons, 0.1 %
 Armour: 1,392 tons, 13.2 %
    - Belts: 412 tons, 3.9 %
    - Torpedo bulkhead: 196 tons, 1.9 %
    - Armament: 241 tons, 2.3 %
    - Armour Deck: 511 tons, 4.9 %
    - Conning Tower: 31 tons, 0.3 %
 Machinery: 3,201 tons, 30.4 %
 Hull, fittings & equipment: 4,554 tons, 43.2 %
 Fuel, ammunition & stores: 999 tons, 9.5 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   11,722 lbs / 5,317 Kg = 108.5 x 6.0 " / 152 mm shells or 1.6 torpedoes
 Stability (Unstable if below 1.00): 1.11
 Metacentric height 2.8 ft / 0.9 m
 Roll period: 14.9 seconds
 Steadiness - As gun platform (Average = 50 %): 52 %
   - Recoil effect (Restricted arc if above 1.00): 0.41
 Seaboat quality  (Average = 1.00): 1.04

Hull form characteristics:
 Hull has a flush deck,
   an extended bulbous bow and large transom stern
 Block coefficient (normal/deep): 0.535 / 0.542
 Length to Beam Ratio: 10.63 : 1
 'Natural speed' for length: 28.58 kts
 Power going to wave formation at top speed: 61 %
 Trim (Max stability = 0, Max steadiness = 100): 50
 Bow angle (Positive = bow angles forward): 10.00 degrees
 Stern overhang: 0.00 ft / 0.00 m
 Freeboard (% = length of deck as a percentage of waterline length):
    Fore end,  Aft end
    - Forecastle: 20.00 %,  34.00 ft / 10.36 m,  26.00 ft / 7.92 m
    - Forward deck: 30.00 %,  26.00 ft / 7.92 m,  22.00 ft / 6.71 m
    - Aft deck: 35.00 %,  22.00 ft / 6.71 m,  20.00 ft / 6.10 m
    - Quarter deck: 15.00 %,  20.00 ft / 6.10 m,  20.00 ft / 6.10 m
    - Average freeboard:  23.39 ft / 7.13 m

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 168.5 %
  - Above water (accommodation/working, high = better): 223.3 %
 Waterplane Area: 27,416 Square feet or 2,547 Square metres
 Displacement factor (Displacement / loading): 113 %
 Structure weight / hull surface area: 104 lbs/sq ft or 507 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.95
  - Longitudinal: 1.64
  - Overall: 1.00
 Hull space for machinery, storage, compartmentation is cramped
 Room for accommodation and workspaces is excellent

1 comment:

James said...

Hello Jim,

I just found your blog through Google and found it interesting to say the least. I was Googling to find out what I could about Battleship design.
Forgive me if I am wrong, but you seem to be designing fictitious (but totally practical)ships of the 1920-30 era?
If that is so then I have an design study for you involving the "refit" of some WW1 ships that you may find interesting.
If so please put a comment on my blog by return and I will tell you more.
I should tell you that I have no knowledge of naval matters just an armchair interest, but I was reading a book of ship designs and just thought "what if...?"

Regards, James in England

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