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Wednesday, July 18, 2007

Beyond reason: the GB/CB/1921 Super Fast (42 knots)

The GB/CB/1921 Super Fast is an exercise to understand the limits of what can be achieved with Springsharp 3.0b2 Beta. As usual, to achieve high speed with a large ship, more length is required. One point that interested me was that I was able to reduce the draft to 30 ft. The ship is 37,294 tons standard displacement. An unreasonable number of shafts (8) are required to deliver the thrust. I would think that this is about the fastest large ship that I have been able to achieve, so far. I would attribute that to the latest version of Springsharp. When I do a design, I experiment by adjusting parameters to get the result that I want. This is the Springsharp report:
GB/CB/1921 Super Fast design study, Great Britain Battlecruiser laid down 1921 (Engine 1945)

Displacement:
 35,976 t light; 37,294 t standard; 38,955 t normal; 40,284 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
 (955.18 ft / 942.00 ft) x 102.00 ft x (30.00 / 30.72 ft)
 (291.14 m / 287.12 m) x 31.09 m  x (9.14 / 9.36 m)

Armament:
      4 - 17.00" / 432 mm 45.0 cal guns - 2,477.44lbs / 1,123.75kg shells, 90 per gun
   Breech loading guns in turret on barbette mounts, 1921 Model
   2 x Twin mounts on centreline, forward deck forward
  1 raised mount - superfiring
      16 - 4.00" / 102 mm 45.0 cal guns - 32.27lbs / 14.64kg shells, 150 per gun
   Quick firing guns in deck and hoist mounts, 1921 Model
   8 x Twin mounts on sides, forward deck aft
  4 raised mounts - superfiring
      Weight of broadside 10,426 lbs / 4,729 kg

Armour:
   - Belts:  Width (max) Length (avg)  Height (avg)
 Main: 5.00" / 127 mm 500.00 ft / 152.40 m 12.00 ft / 3.66 m
 Ends: Unarmoured
   Main Belt covers 82 % of normal length
   Main belt does not fully cover magazines and engineering spaces

   - Torpedo Bulkhead:
  1.00" / 25 mm 500.00 ft / 152.40 m 30.00 ft / 9.14 m

   - Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
 Main: 6.00" / 152 mm 4.00" / 102 mm  6.00" / 152 mm
 2nd: 2.00" / 51 mm 1.00" / 25 mm  2.00" / 51 mm

   - Armoured deck - multiple decks: 2.00" / 51 mm For and Aft decks
 Forecastle: 2.00" / 51 mm  Quarter deck: 2.00" / 51 mm

Machinery:
 Oil fired boilers, steam turbines, 
 Geared drive, 8 shafts, 414,661 shp / 309,337 Kw = 42.00 kts
 Range 5,600nm at 15.00 kts
 Bunker at max displacement = 2,991 tons

Complement:
 1,386 - 1,802

Cost:
 £9.414 million / $37.658 million

Distribution of weights at normal displacement:
 Armament: 1,684 tons, 4.3 %
 Armour: 5,367 tons, 13.8 %
    - Belts: 1,287 tons, 3.3 %
    - Torpedo bulkhead: 555 tons, 1.4 %
    - Armament: 1,108 tons, 2.8 %
    - Armour Deck: 2,417 tons, 6.2 %
 Machinery: 10,471 tons, 26.9 %
 Hull, fittings & equipment: 18,454 tons, 47.4 %
 Fuel, ammunition & stores: 2,979 tons, 7.6 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   43,446 lbs / 19,707 Kg = 17.7 x 17.0 " / 432 mm shells or 4.4 torpedoes
 Stability (Unstable if below 1.00): 1.17
 Metacentric height 6.9 ft / 2.1 m
 Roll period: 16.3 seconds
 Steadiness - As gun platform (Average = 50 %): 52 %
   - Recoil effect (Restricted arc if above 1.00): 0.57
 Seaboat quality  (Average = 1.00): 1.03

Hull form characteristics:
 Hull has a flush deck,
   an extended bulbous bow and large transom stern
 Block coefficient (normal/deep): 0.473 / 0.478
 Length to Beam Ratio: 9.24 : 1
 'Natural speed' for length: 35.37 kts
 Power going to wave formation at top speed: 59 %
 Trim (Max stability = 0, Max steadiness = 100): 50
 Bow angle (Positive = bow angles forward): 15.00 degrees
 Stern overhang: 3.00 ft / 0.91 m
 Freeboard (% = length of deck as a percentage of waterline length):
    Fore end,  Aft end
    - Forecastle: 38.00 %,  38.00 ft / 11.58 m,  31.00 ft / 9.45 m
    - Forward deck: 30.00 %,  31.00 ft / 9.45 m,  31.00 ft / 9.45 m
    - Aft deck: 7.00 %,  31.00 ft / 9.45 m,  31.00 ft / 9.45 m
    - Quarter deck: 25.00 %,  31.00 ft / 9.45 m,  31.00 ft / 9.45 m
    - Average freeboard:  32.06 ft / 9.77 m

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 136.4 %
  - Above water (accommodation/working, high = better): 276.7 %
 Waterplane Area: 64,949 Square feet or 6,034 Square metres
 Displacement factor (Displacement / loading): 109 %
 Structure weight / hull surface area: 194 lbs/sq ft or 948 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.95
  - Longitudinal: 1.57
  - Overall: 1.00
 Hull space for machinery, storage, compartmentation is cramped
 Room for accommodation and workspaces is excellent

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