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Monday, October 06, 2008

A rather unsatisfactory Viper design

I am not sure if it is possible to achieve a good result for an 1898 destroyer in Springsharp. We are going with the very low, but realistic freeboard. This is my rather lame attempt at HMS Viper, the turbine destroyer:
Viper, Great Britain Torpedo Boat Destroyer laid down 1898 (Engine 1917)

Displacement:
 284 t light; 295 t standard; 333 t normal; 365 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
 (210.00 ft / 210.00 ft) x 21.00 ft x (7.25 / 7.66 ft)
 (64.01 m / 64.01 m) x 6.40 m  x (2.21 / 2.33 m)

Armament:
      1 - 3.00" / 76.2 mm 45.0 cal gun - 13.62lbs / 6.18kg shells, 150 per gun
   Quick firing gun in deck mounts, 1898 Model
   2 x Single mounts on centreline, forward deck forward
  1 raised mount - superfiring
      5 - 2.24" / 57.0 mm 45.0 cal guns - 5.70lbs / 2.58kg shells, 150 per gun
   Quick firing guns in deck mounts, 1898 Model
   4 x Single mounts on sides, forward deck aft
   1 x Single mount on centreline, aft deck aft
      Weight of broadside 42 lbs / 19 kg
      Main Torpedoes
      2 - 17.7" / 450 mm, 20.00 ft / 6.10 m torpedoes - 0.650 t each, 1.300 t total
 In 2 sets of deck mounted centre rotating tubes

Machinery:
 Coal fired boilers, steam turbines, 
 Direct drive, 2 shafts, 11,992 shp / 8,946 Kw = 30.00 kts
 Range 2,200nm at 12.00 kts
 Bunker at max displacement = 70 tons (100% coal)
   Caution: Delicate, lightweight machinery

Complement:
 38 - 50

Cost:
 £0.038 million / $0.153 million

Distribution of weights at normal displacement:
 Armament: 11 tons, 3.3 %
    - Guns: 8 tons, 2.5 %
    - Weapons: 3 tons, 0.8 %
 Machinery: 186 tons, 55.7 %
 Hull, fittings & equipment: 87 tons, 26.2 %
 Fuel, ammunition & stores: 49 tons, 14.7 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   69 lbs / 31 Kg = 5.1 x 3.0 " / 76 mm shells or 0.3 torpedoes
 Stability (Unstable if below 1.00): 1.06
 Metacentric height 0.5 ft / 0.2 m
 Roll period: 12.0 seconds
 Steadiness - As gun platform (Average = 50 %): 51 %
   - Recoil effect (Restricted arc if above 1.00): 0.18
 Seaboat quality  (Average = 1.00): 0.51

Hull form characteristics:
 Hull has a flush deck,
   a normal bow and a round stern
 Block coefficient (normal/deep): 0.365 / 0.378
 Length to Beam Ratio: 10.00 : 1
 'Natural speed' for length: 14.49 kts
 Power going to wave formation at top speed: 71 %
 Trim (Max stability = 0, Max steadiness = 100): 100
 Bow angle (Positive = bow angles forward): 0.00 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 %,  9.00 ft / 2.74 m,  8.00 ft / 2.44 m
    - Forward deck: 30.00 %,  8.00 ft / 2.44 m,  7.00 ft / 2.13 m
    - Aft deck: 35.00 %,  7.00 ft / 2.13 m,  7.00 ft / 2.13 m
    - Quarter deck: 15.00 %,  7.00 ft / 2.13 m,  7.00 ft / 2.13 m
    - Average freeboard:  7.43 ft / 2.26 m
 Ship tends to be wet forward

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 186.5 %
  - Above water (accommodation/working, high = better): 65.7 %
 Waterplane Area: 2,654 Square feet or 247 Square metres
 Displacement factor (Displacement / loading): 34 %
 Structure weight / hull surface area: 21 lbs/sq ft or 100 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.48
  - Longitudinal: 1.19
  - Overall: 0.53
 Cramped machinery, storage, compartmentation space
 Cramped accommodation and workspace room
 Caution: Lacks seaworthiness - very limited seakeeping ability

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