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Sunday, September 09, 2007

Another attempt at the Ger/DL/1915 design

The original specification for the Ger/DL1915 design seems to be not feasible in Springsharp. Part of the problem is that the dimensions are small for the displacement. They should work, as they were inspired by the British Scott leaders, which were 1580 tons and 332.5ft x 31.75ft x 12.5ft. They were armed with 5-4.7in guns and 6-21in TT. The speed was to be 36 knots. If the Scott design would work, these should work, as well. This is my original specification:
Ger/DL/1915  332ft x 32ft x 12.7ft   5-5in guns, 4-23,6in TT
  1800 tons  Cp=0.60  Cm=0.8-  
  450 tons oil fuel  2,250 tons full load
  45,000 SHP
  900 tons of machinery   37.4 knots

In fact, only by using a large transom stern, a high freeboard, and a lower displacement and speed, all I was able to achieve was this:
Ger/DL/1915, Germany Destroyer Leader laid down 1915 (Engine 1950)

Displacement:
 1,488 t light; 1,556 t standard; 1,721 t normal; 1,853 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
 (334.82 ft / 332.00 ft) x 32.00 ft x (14.00 / 14.68 ft)
 (102.05 m / 101.19 m) x 9.75 m  x (4.27 / 4.47 m)

Armament:
      5 - 5.00" / 127 mm 45.0 cal guns - 65.00lbs / 29.48kg shells, 150 per gun
   Breech loading guns in deck and hoist mounts, 1915 Model
   4 x Single mounts on centreline ends, evenly spread
  2 raised mounts - superfiring
   1 x Single mount on centreline, forward deck aft
  1 raised mount
      Weight of broadside 325 lbs / 147 kg
      4 - 23.6" / 599 mm, 23.00 ft / 7.01 m torpedoes - 1.818 t each, 7.272 t total
 In 2 sets of deck mounted centre rotating tubes

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

Machinery:
 Oil fired boilers, steam turbines, 
 Geared drive, 2 shafts, 42,851 shp / 31,967 Kw = 35.00 kts
 Range 4,500nm at 14.00 kts
 Bunker at max displacement = 297 tons

Complement:
 133 - 173

Cost:
 £0.288 million / $1.153 million

Distribution of weights at normal displacement:
 Armament: 92 tons, 5.4 %
    - Guns: 85 tons, 4.9 %
    - Torpedoes: 7 tons, 0.4 %
 Armour: 40 tons, 2.4 %
    - Armament: 40 tons, 2.4 %
 Machinery: 830 tons, 48.2 %
 Hull, fittings & equipment: 525 tons, 30.5 %
 Fuel, ammunition & stores: 234 tons, 13.6 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   462 lbs / 210 Kg = 7.4 x 5.0 " / 127 mm shells or 0.3 torpedoes
 Stability (Unstable if below 1.00): 1.07
 Metacentric height 1.0 ft / 0.3 m
 Roll period: 13.2 seconds
 Steadiness - As gun platform (Average = 50 %): 51 %
   - Recoil effect (Restricted arc if above 1.00): 0.96
 Seaboat quality  (Average = 1.00): 1.02

Hull form characteristics:
 Hull has rise forward of midbreak,
   a normal bow and large transom stern
 Block coefficient (normal/deep): 0.405 / 0.416
 Length to Beam Ratio: 10.38 : 1
 'Natural speed' for length: 21.00 kts
 Power going to wave formation at top speed: 70 %
 Trim (Max stability = 0, Max steadiness = 100): 50
 Bow angle (Positive = bow angles forward): 7.00 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 %,  23.00 ft / 7.01 m,  22.00 ft / 6.71 m
    - Forward deck: 14.00 %,  22.00 ft / 6.71 m,  22.00 ft / 6.71 m
    - Aft deck: 51.00 %,  14.00 ft / 4.27 m,  14.00 ft / 4.27 m
    - Quarter deck: 15.00 %,  14.00 ft / 4.27 m,  14.00 ft / 4.27 m
    - Average freeboard:  16.80 ft / 5.12 m

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 171.8 %
  - Above water (accommodation/working, high = better): 119.5 %
 Waterplane Area: 6,807 Square feet or 632 Square metres
 Displacement factor (Displacement / loading): 72 %
 Structure weight / hull surface area: 35 lbs/sq ft or 172 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.45
  - Longitudinal: 3.44
  - Overall: 0.55
 Hull space for machinery, storage, compartmentation is cramped
 Room for accommodation and workspaces is adequate

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