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Saturday, December 09, 2006

I wondered if a smaller large destroyer would still work

I decided that I needed to see if a smaller ship could be designed that would still reach 37 knots and have a decent armament. The result is a GB/DL/1921 with a normal displacement of 2,200 tons. The armament is 6-13cm (5.1in) QF guns, 2-3in AA, and 12-2pdr AA guns, with 8-24in TT. The range is reduced to 4,100 nm at 15 knots. This is the Springsharp report:
GB/DL/1921, Great Britain Destroyer Leader laid down 1921 (Engine 1941)

Displacement:
 1,978 t light; 2,063 t standard; 2,250 t normal; 2,400 t full load

Dimensions: Length overall / water x beam x draught
 385.00 ft / 385.00 ft x 37.00 ft x 13.00 ft (normal load)
 117.35 m / 117.35 m x 11.28 m  x 3.96 m

Armament:
      6 - 5.10" / 130 mm guns (3x2 guns), 66.33lbs / 30.08kg shells, 1921 Model
   Breech loading guns in deck mounts with hoists
   on centreline ends, majority forward, 1 raised mount - superfiring
      2 - 3.00" / 76.2 mm guns in single mounts, 13.50lbs / 6.12kg shells, 1921 Model
   Anti-aircraft guns in deck mounts with hoists
   on side, all amidships, all raised mounts - superfiring
      12 - 1.57" / 40.0 mm guns (3x4 guns), 1.95lbs / 0.89kg shells, 1921 Model
   Anti-aircraft guns in deck mounts 
   on centreline, evenly spread, all raised mounts
 Weight of broadside 448 lbs / 203 kg
 Shells per gun, main battery: 150
 8 - 24.0" / 609.6 mm above water torpedoes

Machinery:
 Oil fired boilers, steam turbines, 
 Geared drive, 2 shafts, 60,010 shp / 44,768 Kw = 37.00 kts
 Range 4,100nm at 15.00 kts
 Bunker at max displacement = 337 tons

Complement:
 163 - 212

Cost:
 £0.731 million / $2.925 million

Distribution of weights at normal displacement:
 Armament: 56 tons, 2.5 %
 Machinery: 1,221 tons, 54.3 %
 Hull, fittings & equipment: 701 tons, 31.2 %
 Fuel, ammunition & stores: 272 tons, 12.1 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   521 lbs / 236 Kg = 7.9 x 5.1 " / 130 mm shells or 0.3 torpedoes
 Stability (Unstable if below 1.00): 1.36
 Metacentric height 1.9 ft / 0.6 m
 Roll period: 11.2 seconds
 Steadiness - As gun platform (Average = 50 %): 50 %
   - Recoil effect (Restricted arc if above 1.00): 0.57
 Seaboat quality  (Average = 1.00): 1.01

Hull form characteristics:
 Hull has rise forward of midbreak
   and transom stern
 Block coefficient: 0.425
 Length to Beam Ratio: 10.41 : 1
 'Natural speed' for length: 22.54 kts
 Power going to wave formation at top speed: 70 %
 Trim (Max stability = 0, Max steadiness = 100): 50
 Bow angle (Positive = bow angles forward): 0.00 degrees
 Stern overhang: 0.00 ft / 0.00 m
 Freeboard (% = measuring location as a percentage of overall length):
    - Stem:  26.00 ft / 7.92 m
    - Forecastle (20 %): 23.00 ft / 7.01 m
    - Mid (33 %):  23.00 ft / 7.01 m (15.00 ft / 4.57 m aft of break)
    - Quarterdeck (15 %): 15.00 ft / 4.57 m
    - Stern:  15.00 ft / 4.57 m
    - Average freeboard: 17.88 ft / 5.45 m

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 194.1 %
  - Above water (accommodation/working, high = better): 88.8 %
 Waterplane Area: 9,255 Square feet or 860 Square metres
 Displacement factor (Displacement / loading): 62 %
 Structure weight / hull surface area: 36 lbs/sq ft or 175 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.43
  - Longitudinal: 2.43
  - Overall: 0.51
 Hull space for machinery, storage, compartmentation is cramped
 Room for accommodation and workspaces is cramped

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