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Friday, July 22, 2005

The GB/DL/1906 redesigned

My friend Cliff's design for a large destroyer or destroyer leader armed with 88mm guns and having a speed of 32 knots works quite nicely, now that I understand better how to use Springsharp. I had originally expected to have to use a much later date for the machinery, and found that wasn't necessary. The dimensions, displacement, armament, and speed are what were originally planned. This is the Springsharp report:
GB/DL/1906, Great Britain Destroyer Leader laid down 1906 (Engine 1917)

Displacement:
 1,023 t light; 1,054 t standard; 1,200 t normal; 1,317 t full load

Dimensions: Length overall / water x beam x draught
 326.77 ft / 326.00 ft x 30.00 ft x 9.00 ft (normal load)
 99.60 m / 99.36 m x 9.14 m  x 2.74 m

Armament:
      4 - 3.46" / 88.0 mm guns in single mounts, 20.00lbs / 9.07kg shells, 1906 Model
   Breech loading guns in deck mounts with hoists
   on centreline ends, evenly spread, 2 raised mounts - superfiring
 Weight of broadside 80 lbs / 36 kg
 Shells per gun, main battery: 150
 2 - 21.0" / 533.4 mm above water torpedoes

Machinery:
 Oil fired boilers, steam turbines, 
 Direct drive, 2 shafts, 29,369 shp / 21,909 Kw = 32.00 kts
 Range 3,200nm at 15.00 kts
 Bunker at max displacement = 263 tons

Complement:
 101 - 132

Cost:
 £0.138 million / $0.554 million

Distribution of weights at normal displacement:
 Armament: 10 tons, 0.9 %
 Machinery: 671 tons, 55.9 %
 Hull, fittings & equipment: 342 tons, 28.5 %
 Fuel, ammunition & stores: 177 tons, 14.7 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   330 lbs / 150 Kg = 15.9 x 3.5 " / 88 mm shells or 0.2 torpedoes
 Stability (Unstable if below 1.00): 1.51
 Metacentric height 1.7 ft / 0.5 m
 Roll period: 9.8 seconds
 Steadiness - As gun platform (Average = 50 %): 57 %
   - Recoil effect (Restricted arc if above 1.00): 0.18
 Seaboat quality  (Average = 1.00): 1.15

Hull form characteristics:
 Hull has rise forward of midbreak
 Block coefficient: 0.477
 Length to Beam Ratio: 10.87 : 1
 'Natural speed' for length: 18.06 kts
 Power going to wave formation at top speed: 68 %
 Trim (Max stability = 0, Max steadiness = 100): 50
 Bow angle (Positive = bow angles forward): 2.00 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 (28 %):  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: 14.40 ft / 4.39 m

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 187.0 %
  - Above water (accommodation/working, high = better): 134.3 %
 Waterplane Area: 6,384 Square feet or 593 Square metres
 Displacement factor (Displacement / loading): 54 %
 Structure weight / hull surface area: 26 lbs/sq ft or 127 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.45
  - Longitudinal: 1.93
  - Overall: 0.53
 Hull space for machinery, storage, compartmentation is cramped
 Room for accommodation and workspaces is excellent

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