A slightly faster version of the 1921 battlecruiser

I wondered what might be achievable if the GB/CB/1921 design that I had just done was given lighter armour. I decreased the belt to 8in, but all I could achieve was 37 knots. To do that required so much power that the number of propellor shafts had to be increased to six. Frank Fox had told me about the power limitation per shaft, so I have been aware of this issue for several years. Frank had said that the limitation per shaft was about 70,000 SHP, although Springsharp apparently uses a figure of 75,000 SHP per shaft. This is the new Springsharp report:

GB/CB/1921 Very Fast, Great Britain Battlecruiser laid down 1921 (Engine 1933)

Displacement:
 41,604 t light; 43,226 t standard; 45,300 t normal; 46,959 t full load

Dimensions: Length overall / water x beam x draught
 870.24 ft / 867.00 ft x 104.00 ft x 31.00 ft (normal load)
 265.25 m / 264.26 m x 31.70 m  x 9.45 m

Armament:
      6 - 16.00" / 406 mm guns (2x3 guns), 2,048.00lbs / 928.96kg shells, 1921 Model
   Breech loading guns in turrets (on barbettes)
   on centreline, all forward, 1 raised mount - superfiring
      16 - 5.50" / 140 mm guns (8x2 guns), 83.19lbs / 37.73kg shells, 1921 Model
   Quick firing guns in turrets (on barbettes)
   on side, all aft
      6 - 4.70" / 119 mm guns in single mounts, 51.91lbs / 23.55kg shells, 1921 Model
   Anti-aircraft guns in deck mounts with hoists
   on side, all amidships, all raised mounts - superfiring
      24 - 1.57" / 40.0 mm guns (6x4 guns), 2.00lbs / 0.91kg shells, 1921 Model
   Anti-aircraft guns in deck mounts 
   on side, evenly spread
 Weight of broadside 13,978 lbs / 6,341 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 8.00 ft / 2.44 m
 Ends: Unarmoured
 Upper: 6.00" / 152 mm 450.00 ft / 137.16 m 8.00 ft / 2.44 m
   Main Belt covers 80 % 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 31.00 ft / 9.45 m

   - Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
 Main: 11.0" / 279 mm 7.00" / 178 mm  11.0" / 279 mm
 2nd: 4.00" / 102 mm 4.00" / 102 mm  4.00" / 102 mm

   - Armour deck: 4.00" / 102 mm, Conning tower: 11.00" / 279 mm

Machinery:
 Oil fired boilers, steam turbines, 
 Geared drive, 6 shafts, 300,638 shp / 224,276 Kw = 37.00 kts
 Range 6,500nm at 15.00 kts
 Bunker at max displacement = 3,734 tons

Complement:
 1,552 - 2,018

Cost:
 £10.564 million / $42.256 million

Distribution of weights at normal displacement:
 Armament: 1,747 tons, 3.9 %
 Armour: 11,432 tons, 25.2 %
    - Belts: 2,235 tons, 4.9 %
    - Torpedo bulkhead: 1,032 tons, 2.3 %
    - Armament: 2,935 tons, 6.5 %
    - Armour Deck: 4,929 tons, 10.9 %
    - Conning Tower: 301 tons, 0.7 %
 Machinery: 8,760 tons, 19.3 %
 Hull, fittings & equipment: 19,665 tons, 43.4 %
 Fuel, ammunition & stores: 3,696 tons, 8.2 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   58,292 lbs / 26,441 Kg = 28.5 x 16.0 " / 406 mm shells or 6.7 torpedoes
 Stability (Unstable if below 1.00): 1.09
 Metacentric height 6.3 ft / 1.9 m
 Roll period: 17.4 seconds
 Steadiness - As gun platform (Average = 50 %): 53 %
   - Recoil effect (Restricted arc if above 1.00): 0.69
 Seaboat quality  (Average = 1.00): 1.02

Hull form characteristics:
 Hull has a flush deck
   and transom stern
 Block coefficient: 0.567
 Length to Beam Ratio: 8.34 : 1
 'Natural speed' for length: 33.83 kts
 Power going to wave formation at top speed: 59 %
 Trim (Max stability = 0, Max steadiness = 100): 52
 Bow angle (Positive = bow angles forward): 5.00 degrees
 Stern overhang: 0.00 ft / 0.00 m
 Freeboard (% = measuring location as a percentage of overall length):
    - Stem:  37.00 ft / 11.28 m
    - Forecastle (20 %): 30.00 ft / 9.14 m
    - Mid (50 %):  30.00 ft / 9.14 m
    - Quarterdeck (15 %): 30.00 ft / 9.14 m
    - Stern:  30.00 ft / 9.14 m
    - Average freeboard: 30.56 ft / 9.31 m

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 113.6 %
  - Above water (accommodation/working, high = better): 245.2 %
 Waterplane Area: 66,606 Square feet or 6,188 Square metres
 Displacement factor (Displacement / loading): 106 %
 Structure weight / hull surface area: 204 lbs/sq ft or 994 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.95
  - Longitudinal: 1.54
  - Overall: 1.00
 Hull space for machinery, storage, compartmentation is cramped
 Room for accommodation and workspaces is excellent