Design study for the Ger/CA/1917 12in guns in the Blue Book

While the 9.4in gunned version of the Ger/CA/1917 was more of just a concept sketch and specifications, the 12in gunned version was more completely designed. The ship was nominally 20,000 tons with 6-12in guns forward and 8-6in guns in twin turrets. The belt was 6in and the deck armour was 3in. The speed was 33 knots. The hull was flush decked, unlike the 9.4in gunned ship. These were the original specifications:

Standard Displacement=20,000 tons    6in belt, 3in+2in decks amid, 1in A/T prot
6-12in/50 (66 tons)  8-6in (8 tons)   725ft x 80ft x 22.7ft Standard
Cp=0.56  Cm=0.95
6,000 tons oil     120,000 SHP = 33 knots    30 SHP/ton machinery

Weights:
Hull        9,850 tons
Mach        4,000 tons
Prot        3,488 tons
Misc        1,600 tons
Arm         1,062 tons
Oil         6,000 tons
Feed Water  1,000 tons
Full load  27,000 tons

This is the actual Springsharp report:

Ger/CA/1917 12in guns, Germany Heavy Cruiser laid down 1917 (Engine 1931)

Displacement:
 20,323 t light; 21,133 t standard; 23,300 t normal; 25,033 t full load

Dimensions: Length overall / water x beam x draught
 727.17 ft / 725.00 ft x 80.00 ft x 23.00 ft (normal load)
 221.64 m / 220.98 m x 24.38 m  x 7.01 m

Armament:
      6 - 12.00" / 305 mm guns (2x3 guns), 864.00lbs / 391.90kg shells, 1917 Model
   Breech loading guns in turrets (on barbettes)
   on centreline, all forward, 1 raised mount - superfiring
      8 - 6.00" / 152 mm guns (4x2 guns), 108.00lbs / 48.99kg shells, 1917 Model
   Breech loading guns in turrets (on barbettes)
   on side, all amidships
 Weight of broadside 6,048 lbs / 2,743 kg
 Shells per gun, main battery: 100

Armour:
   - Belts:  Width (max) Length (avg)  Height (avg)
 Main: 6.00" / 152 mm 415.00 ft / 126.49 m 10.00 ft / 3.05 m
 Ends: Unarmoured
   Main Belt covers 88 % of normal length
   Main belt does not fully cover magazines and engineering spaces

   - Torpedo Bulkhead:
  1.00" / 25 mm 415.00 ft / 126.49 m 23.00 ft / 7.01 m

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

   - Armour deck: 3.00" / 76 mm, Conning tower: 8.00" / 203 mm

Machinery:
 Oil fired boilers, steam turbines, 
 Geared drive, 4 shafts, 159,094 shp / 118,684 Kw = 33.00 kts
 Range 10,000nm at 15.00 kts
 Bunker at max displacement = 3,900 tons

Complement:
 942 - 1,225

Cost:
 £3.659 million / $14.636 million

Distribution of weights at normal displacement:
 Armament: 756 tons, 3.2 %
 Armour: 5,176 tons, 22.2 %
    - Belts: 1,074 tons, 4.6 %
    - Torpedo bulkhead: 353 tons, 1.5 %
    - Armament: 1,229 tons, 5.3 %
    - Armour Deck: 2,379 tons, 10.2 %
    - Conning Tower: 141 tons, 0.6 %
 Machinery: 4,758 tons, 20.4 %
 Hull, fittings & equipment: 9,634 tons, 41.3 %
 Fuel, ammunition & stores: 2,977 tons, 12.8 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   31,348 lbs / 14,219 Kg = 36.3 x 12.0 " / 305 mm shells or 3.7 torpedoes
 Stability (Unstable if below 1.00): 1.17
 Metacentric height 4.8 ft / 1.5 m
 Roll period: 15.3 seconds
 Steadiness - As gun platform (Average = 50 %): 52 %
   - Recoil effect (Restricted arc if above 1.00): 0.61
 Seaboat quality  (Average = 1.00): 1.05

Hull form characteristics:
 Hull has a flush deck
 Block coefficient: 0.611
 Length to Beam Ratio: 9.06 : 1
 'Natural speed' for length: 26.93 kts
 Power going to wave formation at top speed: 57 %
 Trim (Max stability = 0, Max steadiness = 100): 50
 Bow angle (Positive = bow angles forward): 4.00 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 %): 24.00 ft / 7.32 m
    - Mid (71 %):  24.00 ft / 7.32 m
    - Quarterdeck (15 %): 24.00 ft / 7.32 m
    - Stern:  24.00 ft / 7.32 m
    - Average freeboard: 24.56 ft / 7.49 m

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 121.3 %
  - Above water (accommodation/working, high = better): 208.0 %
 Waterplane Area: 42,871 Square feet or 3,983 Square metres
 Displacement factor (Displacement / loading): 112 %
 Structure weight / hull surface area: 152 lbs/sq ft or 740 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.97
  - Longitudinal: 1.28
  - Overall: 1.00
 Hull space for machinery, storage, compartmentation is cramped
 Room for accommodation and workspaces is excellent