The GB/CB/1915

I have a specification for a British battlecruiser that I had over-optimistically hoped could reach 40 knots (on 216,000 SHP). The reality is that the ship can make 34 knots on that power. I scaled back the speed to keep the other parameters as close as possible to what I had specified in the early 1970's. These are my original specifications:

GB/CB/1915  Length=900ft  square root of the length=30  Speed = 40 knots 
Speed-length ratio=1.333

Armament: 6-16.5in BLR, 12-6in QF guns      Power: 5.4 SHP/ton

Displacement: 40,000 tons, full load   216,000 SHP  Cp=0.54  Cm=0.97
Length= 900ft  Beam=100ft  Hull depth=58ft  Draft=29.7ft deep  
Hull weight coefficient = 0.24

40,000 tons full load    2,500nm at 40 knots for 62.5 hours

Weights

3,620 tons fuel oil
  543 tons feed water   consumption=0.616 tons per SHP  57.8 tons per hour
35,837 tons standard
12,528 tons hull
 7,200 tons machinery
 2,875 tons armament
 8,975 tons protection
 2,860 tons miscellaneous
 1,400 tons auxiliary machinery

This is the Springsharp report:

GB/CB/1915, Great Britain Battlecruiser laid down 1915 (Engine 1927)

Displacement:
 34,535 t light; 36,097 t standard; 39,111 t normal; 41,523 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
 (908.08 ft / 900.00 ft) x 100.00 ft x (30.00 / 31.40 ft)
 (276.78 m / 274.32 m) x 30.48 m  x (9.14 / 9.57 m)

Armament:
      6 - 16.50" / 419 mm 45.0 cal guns - 2,265.00lbs / 1,027.39kg shells, 90 per gun
   Breech loading guns in turret on barbette mounts , 1915 Model
   2 x Triple mounts on centreline, forward deck forward
      12 - 6.00" / 152 mm 50.0 cal guns - 100.00lbs / 45.36kg shells, 150 per gun
   Quick firing guns in deck and hoist mounts , 1915 Model
   12 x Single mounts on sides, forward deck aft
  2 raised mounts - superfiring
 Weight of broadside 14,790 lbs / 14,790 kg

Armour:
   - Belts:  Width (max) Length (avg)  Height (avg)
 Main: 7.00" / 178 mm 500.00 ft / 152.40 m 16.00 ft / 4.88 m
 Ends: Unarmoured
   Main Belt covers 85 % of normal length
   Main belt does not fully cover magazines and engineering spaces

   - Torpedo Bulkhead:
  2.00" / 51 mm 500.00 ft / 152.40 m 29.50 ft / 8.99 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: 4.00" / 102 mm 2.00" / 51 mm  4.00" / 102 mm

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

Machinery:
 Oil fired boilers, steam turbines, 
 Geared drive, 4 shafts, 216,239 shp / 161,314 Kw = 34.00 kts
 Range 6,500nm at 18.00 kts
 Bunker at max displacement = 5,427 tons

Complement:
 1,389 - 1,807

Cost:
 £5.200 million / $20.800 million

Distribution of weights at normal displacement:
 Armament: 2,583 tons, 6.6 %
 Armour: 8,791 tons, 22.5 %
    - Belts: 2,419 tons, 6.2 %
    - Torpedo bulkhead: 1,092 tons, 2.8 %
    - Armament: 1,732 tons, 4.4 %
    - Armour Deck: 3,349 tons, 8.6 %
    - Conning Tower: 199 tons, 0.5 %
 Machinery: 6,826 tons, 17.5 %
 Hull, fittings & equipment: 17,239 tons, 44.1 %
 Fuel, ammunition & stores: 4,577 tons, 11.7 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   50,682 lbs / 22,989 Kg = 22.6 x 16.5 " / 419 mm shells or 6.3 torpedoes
 Stability (Unstable if below 1.00): 1.19
 Metacentric height 6.9 ft / 2.1 m
 Roll period: 16.0 seconds
 Steadiness - As gun platform (Average = 50 %): 67 %
   - Recoil effect (Restricted arc if above 1.00): 0.67
 Seaboat quality  (Average = 1.00): 1.35

Hull form characteristics:
 Hull has a flush deck,
   a straight bulbous bow and a cruiser stern
 Block coefficient (normal/deep): 0.507 / 0.514
 Length to Beam Ratio: 9.00 : 1
 'Natural speed' for length: 30.00 kts
 Power going to wave formation at top speed: 50 %
 Trim (Max stability = 0, Max steadiness = 100): 50
 Bow angle (Positive = bow angles forward): 12.00 degrees
 Stern overhang: 0.00 ft / 0.00 m
 Freeboard (% = length of deck as a percentage of waterline length):
    Fore end,  Aft end
    - Forecastle: 30.00 %,  38.00 ft / 11.58 m,  27.00 ft / 8.23 m
    - Forward deck: 30.00 %,  27.00 ft / 8.23 m,  25.00 ft / 7.62 m
    - Aft deck: 25.00 %,  25.00 ft / 7.62 m,  25.00 ft / 7.62 m
    - Quarter deck: 15.00 %,  25.00 ft / 7.62 m,  25.00 ft / 7.62 m
    - Average freeboard:  27.22 ft / 8.30 m

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 111.5 %
  - Above water (accommodation/working, high = better): 211.4 %
 Waterplane Area: 60,349 Square feet or 5,607 Square metres
 Displacement factor (Displacement / loading): 109 %
 Structure weight / hull surface area: 192 lbs/sq ft or 939 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.97
  - Longitudinal: 1.31
  - 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