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Saturday, November 17, 2007

A more faithful version of the Ger/CB/1915 design study

I was looking at the three pages with information about the Ger/CB/1915 design study, and I thought that I needed to try a more faithful representation of the original design. This ended up as a 35 knot battlecruiser with 6-16.5in/45 and 12-6in/50 QF guns. The belt is 8in, inclined at 17 degrees, and is very short. The deck armour is 4in. The torpedo bulkhead is a thin 1.35in, although it is not explicitly listed. I decided that must be right, as there is another place where that thickness is used for splinter protection. The design obviously depends non lightweight machinery:
Ger/CB/1915 design study, Germany Battlecruiser laid down 1915 (Engine 1937)

Displacement:
 38,189 t light; 39,831 t standard; 42,429 t normal; 44,507 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
 (907.86 ft / 900.00 ft) x 100.00 ft x (30.00 / 31.16 ft)
 (276.72 m / 274.32 m) x 30.48 m  x (9.14 / 9.50 m)

Armament:
      6 - 16.50" / 419 mm 45.0 cal guns - 2,265.00lbs / 1,027.39kg shells, 90 per gun
   Breech loading guns in turret on barbette mounts, 1915 Model
   2 x Single mounts on centreline, forward deck forward
  1 raised mount - superfiring
      12 - 6.00" / 152 mm 50.0 cal guns - 114.33lbs / 51.86kg shells, 150 per gun
   Quick firing guns in turret on barbette mounts, 1915 Model
   2 x Twin mounts on sides, forward deck forward
   4 x Twin mounts on sides, aft deck forward
      Weight of broadside 14,962 lbs / 6,787 kg

Armour:
   - Belts:  Width (max) Length (avg)  Height (avg)
 Main: 8.00" / 203 mm 415.00 ft / 126.49 m 8.00 ft / 2.44 m
 Ends: Unarmoured
 Upper: 8.00" / 203 mm 295.00 ft / 89.92 m 8.00 ft / 2.44 m
   Main Belt covers 71 % of normal length
   Main belt does not fully cover magazines and engineering spaces

   - Torpedo Bulkhead:
  1.35" / 34 mm 415.00 ft / 126.49 m 30.00 ft / 9.14 m

   - Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
 Main: 8.00" / 203 mm 6.00" / 152 mm  8.00" / 203 mm
 2nd: 5.00" / 127 mm 3.00" / 76 mm  5.00" / 127 mm

   - Armoured deck - multiple decks: 4.00" / 102 mm For and Aft decks
 Forecastle: 4.00" / 102 mm  Quarter deck: 4.00" / 102 mm

   - Conning towers: Forward 8.00" / 203 mm,  Aft 0.00" / 0 mm

Machinery:
 Oil fired boilers, steam turbines, 
 Geared drive, 4 shafts, 259,880 shp / 193,871 Kw = 35.00 kts
 Range 7,500nm at 16.00 kts
 Bunker at max displacement = 4,676 tons

Complement:
 1,477 - 1,921

Cost:
 £5.463 million / $21.851 million

Distribution of weights at normal displacement:
 Armament: 3,000 tons, 7.1 %
 Armour: 10,236 tons, 24.1 %
    - Belts: 2,083 tons, 4.9 %
    - Torpedo bulkhead: 622 tons, 1.5 %
    - Armament: 2,641 tons, 6.2 %
    - Armour Deck: 4,680 tons, 11.0 %
    - Conning Tower: 210 tons, 0.5 %
 Machinery: 7,203 tons, 17.0 %
 Hull, fittings & equipment: 17,749 tons, 41.8 %
 Fuel, ammunition & stores: 4,240 tons, 10.0 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   59,966 lbs / 27,200 Kg = 26.7 x 16.5 " / 419 mm shells or 6.6 torpedoes
 Stability (Unstable if below 1.00): 1.10
 Metacentric height 6.0 ft / 1.8 m
 Roll period: 17.1 seconds
 Steadiness - As gun platform (Average = 50 %): 62 %
   - Recoil effect (Restricted arc if above 1.00): 0.85
 Seaboat quality  (Average = 1.00): 1.24

Hull form characteristics:
 Hull has low quarterdeck ,
   an extended bulbous bow and a cruiser stern
 Block coefficient (normal/deep): 0.550 / 0.555
 Length to Beam Ratio: 9.00 : 1
 'Natural speed' for length: 30.00 kts
 Power going to wave formation at top speed: 53 %
 Trim (Max stability = 0, Max steadiness = 100): 50
 Bow angle (Positive = bow angles forward): 12.00 degrees
 Stern overhang: 0.00 ft / 0.00 m
 Freeboard (% = length of deck as a percentage of waterline length):
    Fore end,  Aft end
    - Forecastle: 25.00 %,  37.00 ft / 11.28 m,  32.00 ft / 9.75 m
    - Forward deck: 30.00 %,  32.00 ft / 9.75 m,  30.00 ft / 9.14 m
    - Aft deck: 20.00 %,  30.00 ft / 9.14 m,  30.00 ft / 9.14 m
    - Quarter deck: 25.00 %,  22.00 ft / 6.71 m,  22.00 ft / 6.71 m
    - Average freeboard:  29.30 ft / 8.93 m

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 106.6 %
  - Above water (accommodation/working, high = better): 247.9 %
 Waterplane Area: 62,810 Square feet or 5,835 Square metres
 Displacement factor (Displacement / loading): 111 %
 Structure weight / hull surface area: 202 lbs/sq ft or 989 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.96
  - Longitudinal: 1.40
  - Overall: 1.00
 Hull space for machinery, storage, compartmentation is adequate
 Room for accommodation and workspaces is excellent
 Good seaboat, rides out heavy weather easily

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