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Thursday, September 01, 2005

A radical recasting of the Ger/DD/1905 design

Another ship that I recast in 2001 was the Ger/DD/1905 destroyer. My old drawing from 1971 looked vaguely British. The new design is distinctly German with a short forecastle with a well deck containing the forward torpedo tube. One concession to Springsharp that I had to make was to raise the freeboard. That allowed me to keep the shallow draft (9ft). The dimensions are 270ft x 28ft x 9ft, with a normal displacement of 950 tons. The original 900 tons was probably a standard displacement. This is the Springsharp report:
Ger/DD/1905, Germany Destroyer laid down 1905 (Engine 1931)

Displacement:
 817 t light; 845 t standard; 950 t normal; 1,034 t full load

Dimensions: Length overall / water x beam x draught
 270.40 ft / 270.00 ft x 28.00 ft x 9.00 ft (normal load)
 82.42 m / 82.30 m x 8.53 m  x 2.74 m

Armament:
      2 - 4.00" / 102 mm guns in single mounts, 32.00lbs / 14.51kg shells, 1905 Model
   Quick firing guns in deck mounts with hoists
   on centreline, all forward
 Weight of broadside 64 lbs / 29 kg
 Shells per gun, main battery: 250
 2 - 21.0" / 533.4 mm above water torpedoes

Machinery:
 Oil fired boilers, steam turbines, 
 Direct drive, 2 shafts, 29,312 shp / 21,867 Kw = 32.00 kts
 Range 3,200nm at 15.00 kts
 Bunker at max displacement = 189 tons

Complement:
 85 - 111

Cost:
 £0.108 million / $0.432 million

Distribution of weights at normal displacement:
 Armament: 8 tons, 0.8 %
 Machinery: 518 tons, 54.6 %
 Hull, fittings & equipment: 291 tons, 30.6 %
 Fuel, ammunition & stores: 133 tons, 14.0 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   269 lbs / 122 Kg = 8.4 x 4.0 " / 102 mm shells or 0.2 torpedoes
 Stability (Unstable if below 1.00): 1.37
 Metacentric height 1.3 ft / 0.4 m
 Roll period: 10.4 seconds
 Steadiness - As gun platform (Average = 50 %): 53 %
   - Recoil effect (Restricted arc if above 1.00): 0.20
 Seaboat quality  (Average = 1.00): 1.07

Hull form characteristics:
 Hull has rise forward of midbreak
 Block coefficient: 0.489
 Length to Beam Ratio: 9.64 : 1
 'Natural speed' for length: 16.43 kts
 Power going to wave formation at top speed: 74 %
 Trim (Max stability = 0, Max steadiness = 100): 50
 Bow angle (Positive = bow angles forward): 1.00 degrees
 Stern overhang: 0.00 ft / 0.00 m
 Freeboard (% = measuring location as a percentage of overall length):
    - Stem:  23.00 ft / 7.01 m
    - Forecastle (20 %): 21.00 ft / 6.40 m
    - Mid (30 %):  21.00 ft / 6.40 m (13.00 ft / 3.96 m aft of break)
    - Quarterdeck (15 %): 13.00 ft / 3.96 m
    - Stern:  13.00 ft / 3.96 m
    - Average freeboard: 15.56 ft / 4.74 m

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 183.0 %
  - Above water (accommodation/working, high = better): 130.0 %
 Waterplane Area: 4,986 Square feet or 463 Square metres
 Displacement factor (Displacement / loading): 52 %
 Structure weight / hull surface area: 24 lbs/sq ft or 119 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.41
  - Longitudinal: 4.25
  - Overall: 0.52
 Hull space for machinery, storage, compartmentation is cramped
 Room for accommodation and workspaces is excellent

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