Is there something wrong with this? It looks too good: GB/CB/1908 design study

I just ran a design study in Springsharp for a GB/CB/1908 battlecruiser. I wanted to use something like the better data that was erroneously reported in Jane's Fighting Ships, with an 8in belt. This came out better than I expected, so I wondered if I did something wrong that I am not recognizing?:

GB/CB/1908 design study, Great Britain Battlecruiser laid down 1908

Displacement:
 17,177 t light; 17,987 t standard; 20,900 t normal; 23,230 t full load

Dimensions: Length overall / water x beam x draught
 580.00 ft / 580.00 ft x 80.00 ft x 26.50 ft (normal load)
 176.78 m / 176.78 m x 24.38 m  x 8.08 m

Armament:
      4 - 12.00" / 305 mm guns (2x2 guns), 864.00lbs / 391.90kg shells, 1908 Model
   Breech loading guns in turrets (on barbettes)
   on centreline ends, evenly spread
      4 - 12.00" / 305 mm guns (2x2 guns), 864.00lbs / 391.90kg shells, 1908 Model
   Breech loading guns in turrets (on barbettes)
   on side, all amidships
      16 - 4.00" / 102 mm guns in single mounts, 32.00lbs / 14.51kg shells, 1908 Model
   Quick firing guns in casemate mounts 
   on side, evenly spread, 8 raised mounts
 Weight of broadside 7,424 lbs / 3,367 kg
 Shells per gun, main battery: 90

Armour:
   - Belts:  Width (max) Length (avg)  Height (avg)
 Main: 8.00" / 203 mm 390.00 ft / 118.87 m 8.00 ft / 2.44 m
 Ends: 4.00" / 102 mm 190.00 ft / 57.91 m 8.00 ft / 2.44 m
 Upper: 5.00" / 127 mm 390.00 ft / 118.87 m 8.00 ft / 2.44 m
   Main Belt covers 103 % of normal length
   Main belt does not fully cover magazines and engineering spaces

   - Torpedo Bulkhead:
  1.50" / 38 mm 390.00 ft / 118.87 m 26.50 ft / 8.08 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: 8.00" / 203 mm 5.00" / 127 mm  8.00" / 203 mm
 3rd: 4.00" / 102 mm 4.00" / 102 mm  4.00" / 102 mm

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

Machinery:
 Coal fired boilers, steam turbines, 
 Direct drive, 4 shafts, 58,660 shp / 43,760 Kw = 25.50 kts
 Range 5,700nm at 15.00 kts
 Bunker at max displacement = 5,243 tons (100% coal)

Complement:
 868 - 1,129

Cost:
 £1.837 million / $7.348 million

Distribution of weights at normal displacement:
 Armament: 928 tons, 4.4 %
 Armour: 5,349 tons, 25.6 %
    - Belts: 1,963 tons, 9.4 %
    - Torpedo bulkhead: 574 tons, 2.7 %
    - Armament: 1,432 tons, 6.8 %
    - Armour Deck: 1,250 tons, 6.0 %
    - Conning Tower: 131 tons, 0.6 %
 Machinery: 3,259 tons, 15.6 %
 Hull, fittings & equipment: 7,641 tons, 36.6 %
 Fuel, ammunition & stores: 3,723 tons, 17.8 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   27,005 lbs / 12,249 Kg = 31.3 x 12.0 " / 305 mm shells or 3.8 torpedoes
 Stability (Unstable if below 1.00): 1.18
 Metacentric height 4.9 ft / 1.5 m
 Roll period: 15.2 seconds
 Steadiness - As gun platform (Average = 50 %): 65 %
   - Recoil effect (Restricted arc if above 1.00): 0.66
 Seaboat quality  (Average = 1.00): 1.31

Hull form characteristics:
 Hull has rise forward of midbreak
 Block coefficient: 0.595
 Length to Beam Ratio: 7.25 : 1
 'Natural speed' for length: 24.08 kts
 Power going to wave formation at top speed: 52 %
 Trim (Max stability = 0, Max steadiness = 100): 50
 Bow angle (Positive = bow angles forward): -2.00 degrees
 Stern overhang: -2.00 ft / -0.61 m
 Freeboard (% = measuring location as a percentage of overall length):
    - Stem:  27.00 ft / 8.23 m
    - Forecastle (20 %): 24.00 ft / 7.32 m
    - Mid (67 %):  24.00 ft / 7.32 m (16.00 ft / 4.88 m aft of break)
    - Quarterdeck (15 %): 16.00 ft / 4.88 m
    - Stern:  16.00 ft / 4.88 m
    - Average freeboard: 21.60 ft / 6.58 m

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 112.2 %
  - Above water (accommodation/working, high = better): 161.5 %
 Waterplane Area: 33,775 Square feet or 3,138 Square metres
 Displacement factor (Displacement / loading): 108 %
 Structure weight / hull surface area: 152 lbs/sq ft or 742 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.94
  - Longitudinal: 1.69
  - 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