For large, fast ships, length is critical

I often forget this lesson, but I quickly relearn it: large fast ships need adequate length for a variety of reasons (at least in Springsharp). Length decreases the power required and enhances seakeeping. That alone is sufficient reason to go long. I have this design for the GB/CB/1921 Fast, that is not as fast as I would like, but it seems sufficient for now. The GB/CB/1921 has 9-14in/55 guns, 16-5.5in QF guns, 6-4.7in AA guns, and 24-2pdr pompoms. I really don't understand why the protection is rated as well as it is by Springsharp:

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

Displacement:
 39,798 t light; 41,757 t standard; 45,708 t normal; 48,868 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
 (886.65 ft / 874.00 ft) x 104.00 ft x (32.00 / 33.70 ft)
 (270.25 m / 266.40 m) x 31.70 m  x (9.75 / 10.27 m)

Armament:
      9 - 14.00" / 356 mm 55.0 cal guns - 1,485.00lbs / 673.58kg shells, 120 per gun
   Breech loading guns in turret on barbette mounts, 1921 Model
   2 x Triple mounts on centreline, forward deck forward
  3 raised mounts
   1 x Triple mount on centreline, aft deck forward
      16 - 5.50" / 140 mm 55.0 cal guns - 90.00lbs / 40.82kg shells, 150 per gun
   Quick firing guns in turret on barbette mounts, 1921 Model
   8 x Single mounts on sides, forward deck aft
  4 raised mounts - superfiring
      6 - 4.70" / 119 mm 50.0 cal guns - 54.96lbs / 24.93kg shells, 150 per gun
   Anti-air guns in deck and hoist mounts, 1921 Model
   6 x Single mounts on sides, forward deck aft
  6 raised mounts
      24 - 1.57" / 40.0 mm 45.0 cal guns - 1.97lbs / 0.89kg shells, 250 per gun
   Anti-air guns in deck mounts, 1921 Model
   6 x 2 row quad mounts on sides, evenly spread
  6 raised mounts
      Weight of broadside 15,182 lbs / 6,886 kg

Armour:
   - Belts:  Width (max) Length (avg)  Height (avg)
 Main: 6.00" / 152 mm 560.00 ft / 170.69 m 8.00 ft / 2.44 m
 Ends: Unarmoured
 Upper: 4.00" / 102 mm 560.00 ft / 170.69 m 8.00 ft / 2.44 m
   Main Belt covers 99 % of normal length
   Main belt does not fully cover magazines and engineering spaces

   - Torpedo Bulkhead:
  2.00" / 51 mm 560.00 ft / 170.69 m 32.00 ft / 9.75 m

   - Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
 Main: 8.00" / 203 mm 5.00" / 127 mm  8.00" / 203 mm
 2nd: 4.00" / 102 mm 3.00" / 76 mm  4.00" / 102 mm

   - Armoured deck - multiple decks: 3.00" / 76 mm For and Aft decks
 Forecastle: 3.00" / 76 mm  Quarter deck: 3.00" / 76 mm

   - Conning towers: Forward 8.00" / 203 mm,  Aft 0.00" / 0 mm

Machinery:
 Oil fired boilers, steam turbines, 
 Direct drive, 4 shafts, 286,346 shp / 213,614 Kw = 36.00 kts
 Range 8,500nm at 18.00 kts
 Bunker at max displacement = 7,111 tons

Complement:
 1,562 - 2,031

Cost:
 £10.761 million / $43.045 million

Distribution of weights at normal displacement:
 Armament: 3,382 tons, 7.4 %
 Armour: 9,923 tons, 21.7 %
    - Belts: 1,888 tons, 4.1 %
    - Torpedo bulkhead: 1,326 tons, 2.9 %
    - Armament: 2,856 tons, 6.2 %
    - Armour Deck: 3,632 tons, 7.9 %
    - Conning Tower: 220 tons, 0.5 %
 Machinery: 7,936 tons, 17.4 %
 Hull, fittings & equipment: 18,556 tons, 40.6 %
 Fuel, ammunition & stores: 5,910 tons, 12.9 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   58,064 lbs / 26,337 Kg = 42.3 x 14.0 " / 356 mm shells or 7.1 torpedoes
 Stability (Unstable if below 1.00): 1.08
 Metacentric height 6.2 ft / 1.9 m
 Roll period: 17.6 seconds
 Steadiness - As gun platform (Average = 50 %): 52 %
   - Recoil effect (Restricted arc if above 1.00): 0.82
 Seaboat quality  (Average = 1.00): 1.03

Hull form characteristics:
 Hull has low quarterdeck ,
   an extended bulbous bow and small transom stern
 Block coefficient (normal/deep): 0.550 / 0.558
 Length to Beam Ratio: 8.40 : 1
 'Natural speed' for length: 31.87 kts
 Power going to wave formation at top speed: 57 %
 Trim (Max stability = 0, Max steadiness = 100): 50
 Bow angle (Positive = bow angles forward): 15.00 degrees
 Stern overhang: 3.00 ft / 0.91 m
 Freeboard (% = length of deck as a percentage of waterline length):
    Fore end,  Aft end
    - Forecastle: 25.00 %,  36.00 ft / 10.97 m,  30.00 ft / 9.14 m
    - Forward deck: 30.00 %,  30.00 ft / 9.14 m,  30.00 ft / 9.14 m
    - Aft deck: 20.00 %,  30.00 ft / 9.14 m,  30.00 ft / 9.14 m
    - Quarter deck: 25.00 %,  22.00 ft / 6.71 m,  22.00 ft / 6.71 m
    - Average freeboard:  28.60 ft / 8.72 m

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 112.1 %
  - Above water (accommodation/working, high = better): 237.8 %
 Waterplane Area: 64,999 Square feet or 6,039 Square metres
 Displacement factor (Displacement / loading): 108 %
 Structure weight / hull surface area: 210 lbs/sq ft or 1,023 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