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Tuesday, August 01, 2006

The Ger/CB/1905 design from the Blue Book

I am working through the original specifications for the German ships in my building program from 1971. The Ger/CB/1905 design requires moderately lightweight machinery to work. The ship was intended as a low-cost counter to my friend Cliff's more extravagant GB/CB/1905 design. The Ger/CB/1905 was 700ft x 80ft x 24.4ft, with a 19,000 ton Standard displacement and a speed of 31 knots. The armament was 4-12in/45 BLR and 12-4in QF guns. This is the Springsharp report:
Ger/CB/1905, Germany Battlecruiser laid down 1905 (Engine 1909)

Displacement:
 17,533 t light; 18,148 t standard; 20,900 t normal; 23,102 t full load

Dimensions: Length overall / water x beam x draught
 700.00 ft / 700.00 ft x 80.00 ft x 24.40 ft (normal load)
 213.36 m / 213.36 m x 24.38 m  x 7.44 m

Armament:
      4 - 12.00" / 305 mm guns (2x2 guns), 864.00lbs / 391.90kg shells, 1905 Model
   Breech loading guns in turrets (on barbettes)
   on centreline ends, evenly spread
      12 - 4.00" / 102 mm guns in single mounts, 32.00lbs / 14.51kg shells, 1905 Model
   Quick firing guns in casemate mounts 
   on side, all amidships
 Weight of broadside 3,840 lbs / 1,742 kg
 Shells per gun, main battery: 90

Armour:
   - Belts:  Width (max) Length (avg)  Height (avg)
 Main: 4.00" / 102 mm 385.00 ft / 117.35 m 10.00 ft / 3.05 m
 Ends: Unarmoured
 Upper: 3.00" / 76 mm 385.00 ft / 117.35 m 8.00 ft / 2.44 m
   Main Belt covers 85 % of normal length
   Main belt does not fully cover magazines and engineering spaces

   - Torpedo Bulkhead:
  2.00" / 51 mm 385.00 ft / 117.35 m 24.00 ft / 7.32 m

   - Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
 Main: 9.00" / 229 mm 4.00" / 102 mm  8.00" / 203 mm
 2nd: 4.00" / 102 mm 4.00" / 102 mm  4.00" / 102 mm

   - Armour deck: 2.00" / 51 mm, Conning tower: 9.00" / 229 mm

Machinery:
 Oil fired boilers, steam turbines, 
 Direct drive, 4 shafts, 113,554 shp / 84,711 Kw = 31.00 kts
 Range 7,900nm at 15.00 kts
 Bunker at max displacement = 4,954 tons

Complement:
 868 - 1,129

Cost:
 £1.739 million / $6.958 million

Distribution of weights at normal displacement:
 Armament: 480 tons, 2.3 %
 Armour: 4,091 tons, 19.6 %
    - Belts: 1,071 tons, 5.1 %
    - Torpedo bulkhead: 684 tons, 3.3 %
    - Armament: 763 tons, 3.7 %
    - Armour Deck: 1,426 tons, 6.8 %
    - Conning Tower: 147 tons, 0.7 %
 Machinery: 5,162 tons, 24.7 %
 Hull, fittings & equipment: 7,800 tons, 37.3 %
 Fuel, ammunition & stores: 3,367 tons, 16.1 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   27,833 lbs / 12,625 Kg = 32.2 x 12.0 " / 305 mm shells or 3.4 torpedoes
 Stability (Unstable if below 1.00): 1.33
 Metacentric height 5.9 ft / 1.8 m
 Roll period: 13.8 seconds
 Steadiness - As gun platform (Average = 50 %): 67 %
   - Recoil effect (Restricted arc if above 1.00): 0.32
 Seaboat quality  (Average = 1.00): 1.34

Hull form characteristics:
 Hull has rise forward of midbreak
 Block coefficient: 0.535
 Length to Beam Ratio: 8.75 : 1
 'Natural speed' for length: 26.46 kts
 Power going to wave formation at top speed: 53 %
 Trim (Max stability = 0, Max steadiness = 100): 50
 Bow angle (Positive = bow angles forward): -2.00 degrees
 Stern overhang: -2.00 ft / -0.61 m
 Freeboard (% = measuring location as a percentage of overall length):
    - Stem:  31.00 ft / 9.45 m
    - Forecastle (20 %): 26.00 ft / 7.92 m
    - Mid (67 %):  26.00 ft / 7.92 m (18.00 ft / 5.49 m aft of break)
    - Quarterdeck (15 %): 18.00 ft / 5.49 m
    - Stern:  18.00 ft / 5.49 m
    - Average freeboard: 23.76 ft / 7.24 m

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 130.1 %
  - Above water (accommodation/working, high = better): 201.2 %
 Waterplane Area: 38,550 Square feet or 3,581 Square metres
 Displacement factor (Displacement / loading): 114 %
 Structure weight / hull surface area: 134 lbs/sq ft or 652 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.97
  - Longitudinal: 1.32
  - Overall: 1.00
 Hull space for machinery, storage, compartmentation is cramped
 Room for accommodation and workspaces is excellent
 Good seaboat, rides out heavy weather easily

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