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Sunday, May 14, 2006

What I am calling the Ger/CB/1917 design

I have a bare drawing from the Red Book (one that I had skipped) without any specifications or designation, but it is obviously a battlecruiser, and from the context, I would expect that it is German. I took that as the starting point for a Springsharp design. The design is partly inspired by the Richelieu, as there are two turrets forward, although I am certain that they are triple 16.5in turrets. They could have been intended for 6-18in, but that seems excessive, given the shallow draft and rather low displacement. I have assumed that a high speed, such as 35 knots, was intended. They are rather like the US Lexingtons, except with only 6 main battery guns. This is the Springsharp report:
Ger/CB/1917, Germany Battlecruiser laid down 1917 (Engine 1927)

Displacement:
 40,735 t light; 42,383 t standard; 45,000 t normal; 47,093 t full load

Dimensions: Length overall / water x beam x draught
 876.15 ft / 875.00 ft x 105.00 ft x 28.00 ft (normal load)
 267.05 m / 266.70 m x 32.00 m  x 8.53 m

Armament:
      6 - 16.50" / 419 mm guns (2x3 guns), 2,246.06lbs / 1,018.80kg shells, 1917 Model
   Breech loading guns in turrets (on barbettes)
   on centreline, all forward, 1 raised mount - superfiring
      20 - 5.00" / 127 mm guns (10x2 guns), 62.50lbs / 28.35kg shells, 1917 Model
   Quick firing guns in turrets (on barbettes)
   on side, all amidships, 4 raised mounts - superfiring
 Weight of broadside 14,726 lbs / 6,680 kg
 Shells per gun, main battery: 90

Armour:
   - Belts:  Width (max) Length (avg)  Height (avg)
 Main: 8.00" / 203 mm 450.00 ft / 137.16 m 17.00 ft / 5.18 m
 Ends: Unarmoured
   Main Belt covers 79 % of normal length
   Main belt does not fully cover magazines and engineering spaces

   - Torpedo Bulkhead:
  2.00" / 51 mm 450.00 ft / 137.16 m 26.00 ft / 7.92 m

   - Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
 Main: 9.00" / 229 mm 6.00" / 152 mm  9.00" / 229 mm
 2nd: 3.00" / 76 mm 3.00" / 76 mm  3.00" / 76 mm

   - Armour deck: 3.00" / 76 mm, Conning tower: 10.00" / 254 mm

Machinery:
 Oil fired boilers, steam turbines, 
 Geared drive, 6 shafts, 284,942 shp / 212,567 Kw = 35.00 kts
 Range 7,500nm at 15.00 kts
 Bunker at max displacement = 4,710 tons

Complement:
 1,544 - 2,008

Cost:
 £7.693 million / $30.772 million

Distribution of weights at normal displacement:
 Armament: 1,841 tons, 4.1 %
 Armour: 10,196 tons, 22.7 %
    - Belts: 2,723 tons, 6.1 %
    - Torpedo bulkhead: 866 tons, 1.9 %
    - Armament: 2,562 tons, 5.7 %
    - Armour Deck: 3,772 tons, 8.4 %
    - Conning Tower: 273 tons, 0.6 %
 Machinery: 8,994 tons, 20.0 %
 Hull, fittings & equipment: 19,704 tons, 43.8 %
 Fuel, ammunition & stores: 4,265 tons, 9.5 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   56,995 lbs / 25,852 Kg = 25.4 x 16.5 " / 419 mm shells or 6.4 torpedoes
 Stability (Unstable if below 1.00): 1.18
 Metacentric height 7.3 ft / 2.2 m
 Roll period: 16.3 seconds
 Steadiness - As gun platform (Average = 50 %): 51 %
   - Recoil effect (Restricted arc if above 1.00): 0.62
 Seaboat quality  (Average = 1.00): 1.02

Hull form characteristics:
 Hull has rise forward of midbreak
 Block coefficient: 0.612
 Length to Beam Ratio: 8.33 : 1
 'Natural speed' for length: 29.58 kts
 Power going to wave formation at top speed: 56 %
 Trim (Max stability = 0, Max steadiness = 100): 50
 Bow angle (Positive = bow angles forward): 2.00 degrees
 Stern overhang: -1.00 ft / -0.30 m
 Freeboard (% = measuring location as a percentage of overall length):
    - Stem:  33.00 ft / 10.06 m
    - Forecastle (20 %): 31.00 ft / 9.45 m
    - Mid (64 %):  31.00 ft / 9.45 m (23.00 ft / 7.01 m aft of break)
    - Quarterdeck (15 %): 23.00 ft / 7.01 m
    - Stern:  23.00 ft / 7.01 m
    - Average freeboard: 28.28 ft / 8.62 m

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 118.0 %
  - Above water (accommodation/working, high = better): 238.3 %
 Waterplane Area: 67,968 Square feet or 6,314 Square metres
 Displacement factor (Displacement / loading): 105 %
 Structure weight / hull surface area: 205 lbs/sq ft or 1,001 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.98
  - Longitudinal: 1.27
  - Overall: 1.00
 Hull space for machinery, storage, compartmentation is cramped
 Room for accommodation and workspaces is excellent

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