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Friday, November 24, 2006

My It/DD/1934 design: 36 knots for a price

I was able to achieve 36 knots with the It/DD/1934 design by having a deep draft, high freeboard and a considerable displacement. The ship has 4-4.7in QF guns in twin mounts and has 6-21in TT. The dimensions are 350ft x 34ft, so the size is greater than the preceding classes. This is the Springsharp report:
It/DD/1934, Italy Destroyer laid down 1934 (Engine 1950)

Displacement:
 1,904 t light; 1,965 t standard; 2,150 t normal; 2,298 t full load

Dimensions: Length overall / water x beam x draught
 352.19 ft / 350.00 ft x 34.00 ft x 13.00 ft (normal load)
 107.35 m / 106.68 m x 10.36 m  x 3.96 m

Armament:
      4 - 4.70" / 119 mm guns (2 mounts), 51.91lbs / 23.55kg shells, 1934 Model
   Quick firing guns in deck mounts with hoists
   on centreline ends, evenly spread, 1 raised gun
      4 - 1.46" / 37.0 mm guns (2x2 guns), 1.55lbs / 0.70kg shells, 1934 Model
   Anti-aircraft guns in deck mounts with hoists
   on side, all amidships, all raised mounts - superfiring
 Weight of broadside 214 lbs / 97 kg
 Shells per gun, main battery: 150
 6 - 21.0" / 533.4 mm above water torpedoes

Machinery:
 Oil fired boilers, steam turbines, 
 Geared drive, 2 shafts, 69,129 shp / 51,570 Kw = 36.00 kts
 Range 4,200nm at 15.00 kts
 Bunker at max displacement = 333 tons

Complement:
 157 - 205

Cost:
 £1.295 million / $5.181 million

Distribution of weights at normal displacement:
 Armament: 27 tons, 1.2 %
 Machinery: 1,248 tons, 58.1 %
 Hull, fittings & equipment: 629 tons, 29.2 %
 Fuel, ammunition & stores: 246 tons, 11.5 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   483 lbs / 219 Kg = 9.3 x 4.7 " / 119 mm shells or 0.3 torpedoes
 Stability (Unstable if below 1.00): 1.38
 Metacentric height 1.8 ft / 0.5 m
 Roll period: 10.8 seconds
 Steadiness - As gun platform (Average = 50 %): 52 %
   - Recoil effect (Restricted arc if above 1.00): 0.37
 Seaboat quality  (Average = 1.00): 1.03

Hull form characteristics:
 Hull has rise forward of midbreak
 Block coefficient: 0.486
 Length to Beam Ratio: 10.29 : 1
 'Natural speed' for length: 18.71 kts
 Power going to wave formation at top speed: 73 %
 Trim (Max stability = 0, Max steadiness = 100): 50
 Bow angle (Positive = bow angles forward): 5.00 degrees
 Stern overhang: 0.00 ft / 0.00 m
 Freeboard (% = measuring location as a percentage of overall length):
    - Stem:  25.00 ft / 7.62 m
    - Forecastle (20 %): 23.00 ft / 7.01 m
    - Mid (42 %):  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: 18.52 ft / 5.64 m

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 196.8 %
  - Above water (accommodation/working, high = better): 109.8 %
 Waterplane Area: 7,832 Square feet or 728 Square metres
 Displacement factor (Displacement / loading): 61 %
 Structure weight / hull surface area: 33 lbs/sq ft or 162 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.42
  - Longitudinal: 3.59
  - Overall: 0.52
 Hull space for machinery, storage, compartmentation is cramped
 Room for accommodation and workspaces is adequate

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