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Friday, December 23, 2005

A new design series starting with the GB/DD/1914

One of my main concerns about Springsharp is that destroyer machinery is too heavy. I believe that this will eventually be corrected, perhaps in the next version. I thought that the next design series should study British destroyers. This is my concept for a 1914 British design: the GB/DD/1914. I wanted 1,000 tons , or so, at least 34 knots, and a 3,500nm range. The armament is not particularly interesting, but reasonable at 4-4in QF, 1-6pdr AA, and 4-21in TT. One gun is superfiring. This is the Springsharp report:
GB/DD/1914, Great Britain Destroyer laid down 1914 (Engine 1918)

Displacement:
    923 t light; 959 t standard; 1,040 t normal; 1,105 t full load

Dimensions: Length overall / water x beam x draught
    280.00 ft / 280.00 ft x 29.00 ft x 12.00 ft (normal load)
    85.34 m / 85.34 m x 8.84 m  x 3.66 m

Armament:
      4 - 4.00" / 102 mm guns in single mounts, 32.00lbs / 14.51kg shells, 1914 Model
      Quick firing guns in deck mounts with hoists
      on centreline ends, evenly spread, 1 raised mount
      1 - 2.24" / 57.0 mm guns in single mounts, 5.65lbs / 2.56kg shells, 1914 Model
      Anti-aircraft gun in deck mount
      on side amidships
    Weight of broadside 134 lbs / 61 kg
    Shells per gun, main battery: 200
    4 - 21.0" / 533.4 mm above water torpedoes

Machinery:
    Oil fired boilers, steam turbines,
    Direct drive, 2 shafts, 29,517 shp / 22,020 Kw = 34.00 kts
    Range 3,500nm at 12.00 kts
    Bunker at max displacement = 146 tons

Complement:
    91 - 119

Cost:
    £0.161 million / $0.646 million

Distribution of weights at normal displacement:
    Armament: 17 tons, 1.6 %
    Machinery: 575 tons, 55.3 %
    Hull, fittings & equipment: 331 tons, 31.8 %
    Fuel, ammunition & stores: 117 tons, 11.3 %
    Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
    Survivability (Non-critical penetrating hits needed to sink ship):
      257 lbs / 117 Kg = 8.0 x 4.0 " / 102 mm shells or 0.2 torpedoes
    Stability (Unstable if below 1.00): 1.35
    Metacentric height 1.3 ft / 0.4 m
    Roll period: 10.6 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
      and transom stern
    Block coefficient: 0.374
    Length to Beam Ratio: 9.66 : 1
    'Natural speed' for length: 19.50 kts
    Power going to wave formation at top speed: 72 %
    Trim (Max stability = 0, Max steadiness = 100): 50
    Bow angle (Positive = bow angles forward): 0.00 degrees
    Stern overhang: 0.00 ft / 0.00 m
    Freeboard (% = measuring location as a percentage of overall length):
       - Stem:        22.00 ft / 6.71 m
       - Forecastle (20 %):    20.00 ft / 6.10 m
       - Mid (35 %):        20.00 ft / 6.10 m (12.00 ft / 3.66 m aft of break)
       - Quarterdeck (15 %):    12.00 ft / 3.66 m
       - Stern:        12.00 ft / 3.66 m
       - Average freeboard:    14.96 ft / 4.56 m

Ship space, strength and comments:
    Space    - Hull below water (magazines/engines, low = better): 191.1 %
        - Above water (accommodation/working, high = better): 98.1 %
    Waterplane Area: 5,125 Square feet or 476 Square metres
    Displacement factor (Displacement / loading): 46 %
    Structure weight / hull surface area: 28 lbs/sq ft or 135 Kg/sq metre
    Hull strength (Relative):
        - Cross-sectional: 0.42
        - Longitudinal: 3.99
        - Overall: 0.53
    Hull space for machinery, storage, compartmentation is cramped
    Room for accommodation and workspaces is adequate

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