Extreme speed at a cost

Perhaps no one but me was interested in knowing what would be required to drive a light battlecruiser to 45 knots. Since I have long had an interest in some these really extreme speeds, I decided to "go for it". The armament is 4-17in BLR and 12-5.5in QF guns. The armour basis is 8in. The deck is just 2in, as is the torpedo bulkhead. The ship is extremely long and has a ridiculous number of shafts (9). This is the Springsharp report:

GB/CB/1921 Super Fast-Alt 2 Version, Great Britain Battlecruiser laid down 1921 (Engine 1945)

Displacement:
 47,394 t light; 48,989 t standard; 50,769 t normal; 52,193 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
 (1,050.87 ft / 1,040.00 ft) x 108.00 ft x (35.00 / 35.67 ft)
 (320.30 m / 316.99 m) x 32.92 m  x (10.67 / 10.87 m)

Armament:
      4 - 17.00" / 432 mm 45.0 cal guns - 2,475.00lbs / 1,122.64kg shells, 90 per gun
   Breech loading guns in turret on barbette mounts , 1921 Model
   2 x Twin mounts on centreline ends, evenly spread
      12 - 5.50" / 140 mm 45.0 cal guns - 83.90lbs / 38.05kg shells, 150 per gun
   Quick firing guns in deck and hoist mount , 1921 Model
   1 x Twin mount on sides amidships
 Weight of broadside 10,907 lbs / 10,907 kg

Armour:
   - Belts:  Width (max) Length (avg)  Height (avg)
 Main: 8.00" / 203 mm 565.00 ft / 172.21 m 12.00 ft / 3.66 m
 Ends: Unarmoured
   Main Belt covers 84 % of normal length
   Main belt does not fully cover magazines and engineering spaces

   - Torpedo Bulkhead:
  2.00" / 51 mm 565.00 ft / 172.21 m 34.00 ft / 10.36 m

   - Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
 Main: 9.00" / 229 mm 5.00" / 127 mm  8.00" / 203 mm
 2nd: 4.00" / 102 mm 1.00" / 25 mm  4.00" / 102 mm

   - Armour deck: 2.00" / 51 mm, Conning tower: 8.00" / 203 mm

Machinery:
 Oil fired boilers, steam turbines, 
 Geared drive, 9 shafts, 609,116 shp / 454,400 Kw = 45.00 kts
 Range 5,400nm at 15.00 kts
 Bunker at max displacement = 3,204 tons

Complement:
 1,690 - 2,198

Cost:
 £12.297 million / $49.190 million

Distribution of weights at normal displacement:
 Armament: 1,786 tons, 3.5 %
 Armour: 8,062 tons, 15.9 %
    - Belts: 2,327 tons, 4.6 %
    - Torpedo bulkhead: 1,422 tons, 2.8 %
    - Armament: 1,318 tons, 2.6 %
    - Armour Deck: 2,758 tons, 5.4 %
    - Conning Tower: 236 tons, 0.5 %
 Machinery: 15,382 tons, 30.3 %
 Hull, fittings & equipment: 22,738 tons, 44.8 %
 Fuel, ammunition & stores: 3,374 tons, 6.6 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   49,541 lbs / 22,471 Kg = 20.2 x 17.0 " / 432 mm shells or 5.2 torpedoes
 Stability (Unstable if below 1.00): 1.23
 Metacentric height 8.1 ft / 2.5 m
 Roll period: 15.9 seconds
 Steadiness - As gun platform (Average = 50 %): 51 %
   - Recoil effect (Restricted arc if above 1.00): 0.40
 Seaboat quality  (Average = 1.00): 1.02

Hull form characteristics:
 Hull has a flush deck,
   a normal bow and small transom stern
 Block coefficient (normal/deep): 0.452 / 0.456
 Length to Beam Ratio: 9.63 : 1
 'Natural speed' for length: 37.14 kts
 Power going to wave formation at top speed: 59 %
 Trim (Max stability = 0, Max steadiness = 100): 50
 Bow angle (Positive = bow angles forward): 12.00 degrees
 Stern overhang: 3.00 ft / 0.91 m
 Freeboard (% = length of deck as a percentage of waterline length):
    Fore end,  Aft end
    - Forecastle: 20.00 %,  37.00 ft / 11.28 m,  33.00 ft / 10.06 m
    - Forward deck: 30.00 %,  33.00 ft / 10.06 m,  33.00 ft / 10.06 m
    - Aft deck: 35.00 %,  33.00 ft / 10.06 m,  33.00 ft / 10.06 m
    - Quarter deck: 15.00 %,  33.00 ft / 10.06 m,  34.00 ft / 10.36 m
    - Average freeboard:  33.40 ft / 10.18 m

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 142.7 %
  - Above water (accommodation/working, high = better): 277.3 %
 Waterplane Area: 74,548 Square feet or 6,926 Square metres
 Displacement factor (Displacement / loading): 105 %
 Structure weight / hull surface area: 198 lbs/sq ft or 969 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.96
  - Longitudinal: 1.44
  - Overall: 1.00
 Hull space for machinery, storage, compartmentation is cramped
 Room for accommodation and workspaces is excellent