A really extreme design: Ger/CBL/1915 Mod.A

This is a design study that I did about 1971. It was for an extremely fast light battlecruiser. I had hoped for 40 knots, but 37 knots seems about all that is feasible. I'm still amazed that it does as well as it does. This sort of ship has a pre-Dreadnought flavor to it, due to having only two large caliber guns. You would think it was an 1880's design, except for the more modern configuration. It sacrifices armour and armament to achieve an extreme speed. This is the Springsharp report:

Ger/CBL/1915 Mod.A, Germany Light Battlecruiser laid down 1915 (Engine 1941)

Displacement:
 18,430 t light; 18,974 t standard; 20,000 t normal; 20,821 t full load

Dimensions: Length overall / water x beam x draught
 803.15 ft / 800.00 ft x 80.00 ft x 22.00 ft (normal load)
 244.80 m / 243.84 m x 24.38 m  x 6.71 m

Armament:
      2 - 12.00" / 305 mm guns (1x2 guns), 864.00lbs / 391.90kg shells, 1915 Model
   Breech loading guns in a turret (on a barbette)
   on centreline forward
      12 - 6.00" / 152 mm guns in single mounts, 108.00lbs / 48.99kg shells, 1915 Model
   Quick firing guns in deck mounts with hoists
   on side, all amidships
 Weight of broadside 3,024 lbs / 1,372 kg
 Shells per gun, main battery: 80

Armour:
   - Belts:  Width (max) Length (avg)  Height (avg)
 Main: 4.00" / 102 mm 640.00 ft / 195.07 m 17.00 ft / 5.18 m
 Ends: Unarmoured
   Main Belt covers 123 % of normal length
   Main belt does not fully cover magazines and engineering spaces

   - Torpedo Bulkhead:
  1.50" / 38 mm 640.00 ft / 195.07 m 19.00 ft / 5.79 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       -         -

   - Armour deck: 1.00" / 25 mm, Conning tower: 4.00" / 102 mm

Machinery:
 Oil fired boilers, steam turbines, 
 Geared drive, 4 shafts, 206,306 shp / 153,904 Kw = 37.00 kts
 Range 5,400nm at 15.00 kts
 Bunker at max displacement = 1,846 tons

Complement:
 840 - 1,093

Cost:
 £2.510 million / $10.041 million

Distribution of weights at normal displacement:
 Armament: 378 tons, 1.9 %
 Armour: 3,678 tons, 18.4 %
    - Belts: 1,756 tons, 8.8 %
    - Torpedo bulkhead: 675 tons, 3.4 %
    - Armament: 397 tons, 2.0 %
    - Armour Deck: 787 tons, 3.9 %
    - Conning Tower: 63 tons, 0.3 %
 Machinery: 5,452 tons, 27.3 %
 Hull, fittings & equipment: 8,922 tons, 44.6 %
 Fuel, ammunition & stores: 1,570 tons, 7.8 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   28,481 lbs / 12,919 Kg = 33.0 x 12.0 " / 305 mm shells or 3.3 torpedoes
 Stability (Unstable if below 1.00): 1.26
 Metacentric height 5.5 ft / 1.7 m
 Roll period: 14.4 seconds
 Steadiness - As gun platform (Average = 50 %): 63 %
   - Recoil effect (Restricted arc if above 1.00): 0.33
 Seaboat quality  (Average = 1.00): 1.26

Hull form characteristics:
 Hull has rise forward of midbreak
 Block coefficient: 0.497
 Length to Beam Ratio: 10.00 : 1
 'Natural speed' for length: 28.28 kts
 Power going to wave formation at top speed: 55 %
 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:  33.00 ft / 10.06 m
    - Forecastle (20 %): 30.00 ft / 9.14 m
    - Mid (67 %):  30.00 ft / 9.14 m (22.00 ft / 6.71 m aft of break)
    - Quarterdeck (15 %): 22.00 ft / 6.71 m
    - Stern:  22.00 ft / 6.71 m
    - Average freeboard: 27.60 ft / 8.41 m

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 137.0 %
  - Above water (accommodation/working, high = better): 268.0 %
 Waterplane Area: 42,532 Square feet or 3,951 Square metres
 Displacement factor (Displacement / loading): 114 %
 Structure weight / hull surface area: 133 lbs/sq ft or 651 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.96
  - Longitudinal: 1.40
  - 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