A tweak raises the GB/CB/1933 speed to 42 knots

I made a few adjustments to have a 6in lower belt, 4in deck, and 42 knots of speed for the GB/CB/1933 battlecruiser. The armament is now 6-12in guns in two triple turrets forward, 20-4.5in DP and 32-2pdr AA guns. The 8 propellor shafts are a rather bizarre feature and would be hard to implement. They are necessary due to the great power and the 75,000 (in Springsharp) limitation for SHP/shaft. This is the Springsharp report:

GB/CB/1933 12in guns 42 knots, Great Britain Battlecruiser laid down 1933 (Engine 1941)

Displacement:
 42,721 t light; 43,985 t standard; 47,200 t normal; 49,772 t full load

Dimensions: Length overall / water x beam x draught
 927.32 ft / 924.00 ft x 116.00 ft x 35.00 ft (normal load)
 282.65 m / 281.64 m x 35.36 m  x 10.67 m

Armament:
      6 - 12.00" / 305 mm guns (2x3 guns), 864.00lbs / 391.90kg shells, 1933 Model
   Breech loading guns in turrets (on barbettes)
   on side, all forward, 1 raised mount - superfiring
      20 - 4.50" / 114 mm guns (10x2 guns), 45.56lbs / 20.67kg shells, 1933 Model
   Dual purpose guns in turrets (on barbettes)
   on side, all amidships
      32 - 1.57" / 40.0 mm guns (6 mounts), 1.95lbs / 0.89kg shells, 1933 Model
   Anti-aircraft guns in deck mounts with hoists
   on side, all amidships, 4 raised mounts - superfiring
 Weight of broadside 6,158 lbs / 2,793 kg
 Shells per gun, main battery: 90

Armour:
   - Belts:  Width (max) Length (avg)  Height (avg)
 Main: 6.00" / 152 mm 590.00 ft / 179.83 m 8.00 ft / 2.44 m
 Ends: Unarmoured
 Upper: 4.00" / 102 mm 590.00 ft / 179.83 m 8.00 ft / 2.44 m
   Main Belt covers 98 % of normal length
   Main belt does not fully cover magazines and engineering spaces

   - Torpedo Bulkhead:
  2.00" / 51 mm 590.00 ft / 179.83 m 35.00 ft / 10.67 m

   - Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
 Main: 7.00" / 178 mm 5.00" / 127 mm  7.00" / 178 mm
 2nd: 3.00" / 76 mm 3.00" / 76 mm  3.00" / 76 mm

   - Armour deck: 4.00" / 102 mm, Conning tower: 7.00" / 178 mm

Machinery:
 Oil fired boilers, steam turbines, 
 Geared drive, 8 shafts, 462,094 shp / 344,722 Kw = 42.00 kts
 Range 7,500nm at 18.00 kts
 Bunker at max displacement = 5,786 tons

Complement:
 1,600 - 2,081

Cost:
 £18.207 million / $72.828 million

Distribution of weights at normal displacement:
 Armament: 770 tons, 1.6 %
 Armour: 10,559 tons, 22.4 %
    - Belts: 2,003 tons, 4.2 %
    - Torpedo bulkhead: 1,528 tons, 3.2 %
    - Armament: 1,617 tons, 3.4 %
    - Armour Deck: 5,214 tons, 11.0 %
    - Conning Tower: 197 tons, 0.4 %
 Machinery: 12,212 tons, 25.9 %
 Hull, fittings & equipment: 19,181 tons, 40.6 %
 Fuel, ammunition & stores: 4,479 tons, 9.5 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   65,559 lbs / 29,737 Kg = 75.9 x 12.0 " / 305 mm shells or 7.9 torpedoes
 Stability (Unstable if below 1.00): 1.29
 Metacentric height 9.8 ft / 3.0 m
 Roll period: 15.6 seconds
 Steadiness - As gun platform (Average = 50 %): 52 %
   - Recoil effect (Restricted arc if above 1.00): 0.19
 Seaboat quality  (Average = 1.00): 1.05

Hull form characteristics:
 Hull has a flush deck
   and transom stern
 Block coefficient: 0.440
 Length to Beam Ratio: 7.97 : 1
 'Natural speed' for length: 35.64 kts
 Power going to wave formation at top speed: 61 %
 Trim (Max stability = 0, Max steadiness = 100): 50
 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:  38.00 ft / 11.58 m
    - Forecastle (20 %): 32.00 ft / 9.75 m
    - Mid (35 %):  32.00 ft / 9.75 m
    - Quarterdeck (15 %): 32.00 ft / 9.75 m
    - Stern:  32.00 ft / 9.75 m
    - Average freeboard: 32.48 ft / 9.90 m

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 116.6 %
  - Above water (accommodation/working, high = better): 268.4 %
 Waterplane Area: 70,459 Square feet or 6,546 Square metres
 Displacement factor (Displacement / loading): 115 %
 Structure weight / hull surface area: 185 lbs/sq ft or 902 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.95
  - Longitudinal: 1.67
  - Overall: 1.00
 Hull space for machinery, storage, compartmentation is cramped
 Room for accommodation and workspaces is excellent