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Sunday, July 31, 2005

My design for the Meteor (my Ger/DM/1913 specification)

I had named my design for a fast destroyer-minelayer Meteor, after the real German minelayer. I had originally called it that Ger/ML/1913, but Ger/DM/1913 seems more appropriate. My nominal displacement target was 1,600 tons, but I have a note that more realistically raised that to 1,850 tons. That allows for a stronger hull and improved seakeeping. It still relies upon the lightest weight machinery possible. The dimensions were specified as 350ft x 36ft, with no draft listed. The speed target was 35 knots, while I had hoped for more, at least a year or so later. It seems not to be reaonable, at least when using Springsharp and requiring both hull strength and adequate seakeeping ability. This is the Springsharp report:
Ger/DM/1913 (Meteor), Germany Destroyer-Minelayer laid down 1913 (Engine 1950)

Displacement:
 1,723 t light; 1,771 t standard; 1,850 t normal; 1,914 t full load

Dimensions: Length overall / water x beam x draught
 350.77 ft / 350.00 ft x 36.00 ft x 17.00 ft (normal load)
 106.91 m / 106.68 m x 10.97 m  x 5.18 m

Armament:
      2 - 6.00" / 152 mm guns in single mounts, 108.00lbs / 48.99kg shells, 1913 Model
   Quick firing guns in deck mounts with hoists
   on centreline ends, evenly spread
 Weight of broadside 216 lbs / 98 kg
 Shells per gun, main battery: 90

Machinery:
 Oil fired boilers, steam turbines, 
 Direct drive, 2 shafts, 49,596 shp / 36,998 Kw = 35.00 kts
 Range 2,100nm at 14.00 kts
 Bunker at max displacement = 143 tons

Complement:
 140 - 183

Cost:
 £0.229 million / $0.916 million

Distribution of weights at normal displacement:
 Armament: 27 tons, 1.5 %
 Machinery: 906 tons, 49.0 %
 Hull, fittings & equipment: 540 tons, 29.2 %
 Fuel, ammunition & stores: 127 tons, 6.9 %
 Miscellaneous weights: 250 tons, 13.5 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   410 lbs / 186 Kg = 3.8 x 6.0 " / 152 mm shells or 0.3 torpedoes
 Stability (Unstable if below 1.00): 1.12
 Metacentric height 1.3 ft / 0.4 m
 Roll period: 13.1 seconds
 Steadiness - As gun platform (Average = 50 %): 55 %
   - Recoil effect (Restricted arc if above 1.00): 0.30
 Seaboat quality  (Average = 1.00): 1.09

Hull form characteristics:
 Hull has rise forward of midbreak
 Block coefficient: 0.302
 Length to Beam Ratio: 9.72 : 1
 'Natural speed' for length: 18.71 kts
 Power going to wave formation at top speed: 64 %
 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 (34 %):  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: 14.88 ft / 4.54 m

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 183.3 %
  - Above water (accommodation/working, high = better): 150.3 %
 Waterplane Area: 8,048 Square feet or 748 Square metres
 Displacement factor (Displacement / loading): 65 %
 Structure weight / hull surface area: 35 lbs/sq ft or 169 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.44
  - Longitudinal: 2.42
  - Overall: 0.52
 Hull space for machinery, storage, compartmentation is cramped
 Room for accommodation and workspaces is excellent

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