I was able to squeeze 38 knots out of a 34,620 ton Standard displacement

I wondered if I might be able to have a fast battlecruiser make 38 knots. The answer is yes, but only at the cost of having 6 shafts, which is bad. Back in the 1970's, I had believe the stories about the nuclear-powered aircraft carrier Enterprise making 60 knots, but I know now that it was not possible. The Enterprise had a four-shaft plant, and there is always the 75,000 or so shaft loading limitation. That is the issue with this version of a GB/CB/1921 fast battlecruiser. To reach 38 knots, even on a relatively low displacement still takes a great deal of power. To use that much power requires six shafts, which are difficult to accommodate in a narrow ship. This is the Springsharp report for this design, which has only a 5in belt:

GB/CB/1921 Very Fast, Great Britain Battlecruiser laid down 1921 (Engine 1937)

Displacement:
 33,421 t light; 34,620 t standard; 36,400 t normal; 37,824 t full load

Dimensions: Length overall / water x beam x draught
 854.52 ft / 852.00 ft x 102.00 ft x 30.00 ft (normal load)
 260.46 m / 259.69 m x 31.09 m  x 9.14 m

Armament:
      6 - 14.00" / 356 mm guns (2x3 guns), 1,372.00lbs / 622.33kg shells, 1921 Model
   Breech loading guns in turrets (on barbettes)
   on centreline, all forward, 1 raised mount - superfiring
      12 - 5.50" / 140 mm guns (6x2 guns), 83.19lbs / 37.73kg shells, 1921 Model
   Quick firing guns in turrets (on barbettes)
   on side, all aft
 Weight of broadside 9,230 lbs / 4,187 kg
 Shells per gun, main battery: 90

Armour:
   - Belts:  Width (max) Length (avg)  Height (avg)
 Main: 5.00" / 127 mm 410.00 ft / 124.97 m 16.00 ft / 4.88 m
 Ends: Unarmoured
   Main Belt covers 74 % of normal length
   Main belt does not fully cover magazines and engineering spaces

   - Torpedo Bulkhead:
  2.00" / 51 mm 410.00 ft / 124.97 m 28.00 ft / 8.53 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: 4.00" / 102 mm 4.00" / 102 mm  4.00" / 102 mm

   - Armour deck: 3.00" / 76 mm, Conning tower: 6.00" / 152 mm

Machinery:
 Oil fired boilers, steam turbines, 
 Geared drive, 6 shafts, 330,537 shp / 246,581 Kw = 38.00 kts
 Range 6,400nm at 15.00 kts
 Bunker at max displacement = 3,204 tons

Complement:
 1,316 - 1,712

Cost:
 £8.709 million / $34.837 million

Distribution of weights at normal displacement:
 Armament: 1,154 tons, 3.2 %
 Armour: 7,124 tons, 19.6 %
    - Belts: 1,471 tons, 4.0 %
    - Torpedo bulkhead: 850 tons, 2.3 %
    - Armament: 1,481 tons, 4.1 %
    - Armour Deck: 3,181 tons, 8.7 %
    - Conning Tower: 142 tons, 0.4 %
 Machinery: 9,161 tons, 25.2 %
 Hull, fittings & equipment: 15,982 tons, 43.9 %
 Fuel, ammunition & stores: 2,979 tons, 8.2 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   41,544 lbs / 18,844 Kg = 30.3 x 14.0 " / 356 mm shells or 4.7 torpedoes
 Stability (Unstable if below 1.00): 1.23
 Metacentric height 7.5 ft / 2.3 m
 Roll period: 15.7 seconds
 Steadiness - As gun platform (Average = 50 %): 52 %
   - Recoil effect (Restricted arc if above 1.00): 0.44
 Seaboat quality  (Average = 1.00): 1.04

Hull form characteristics:
 Hull has rise forward of midbreak
 Block coefficient: 0.489
 Length to Beam Ratio: 8.35 : 1
 'Natural speed' for length: 29.19 kts
 Power going to wave formation at top speed: 58 %
 Trim (Max stability = 0, Max steadiness = 100): 50
 Bow angle (Positive = bow angles forward): 4.00 degrees
 Stern overhang: -2.00 ft / -0.61 m
 Freeboard (% = measuring location as a percentage of overall length):
    - Stem:  36.00 ft / 10.97 m
    - Forecastle (20 %): 30.00 ft / 9.14 m
    - Mid (76 %):  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: 28.56 ft / 8.71 m

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 131.1 %
  - Above water (accommodation/working, high = better): 239.7 %
 Waterplane Area: 57,312 Square feet or 5,324 Square metres
 Displacement factor (Displacement / loading): 105 %
 Structure weight / hull surface area: 187 lbs/sq ft or 911 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.95
  - Longitudinal: 1.51
  - Overall: 1.00
 Hull space for machinery, storage, compartmentation is cramped
 Room for accommodation and workspaces is excellent