You can easily specify ships which are not a viable design

My original specification for a GB/CB/1915 battlecruiser would not work as specified. The beam was too narrow for the armament. I had wanted 10-15in/45 (I have used 15in/42 instead) and 16-5in QF guns. The dimensions were to be 800ft x 90ft x 26.5ft with 136,600 SHP at maximum overload power. The turrets and barbettes were 9in and the belt was 6in. I had hoped for some high speed beyond what is reasonable. I had to increase the beam to 104ft and lower the freeboard to have a design with acceptable recoil behavior. This is the Springsharp report:

GB/CB/1915, Great Britain Battlecruiser laid down 1915 (Engine 1937)

Displacement:
 33,086 t light; 35,551 t standard; 37,688 t normal; 39,397 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
 (807.00 ft / 800.00 ft) x 102.00 ft x (26.50 / 27.49 ft)
 (245.97 m / 243.84 m) x 31.09 m  x (8.08 / 8.38 m)

Armament:
      10 - 15.00" / 381 mm 42.0 cal guns - 1,950.00lbs / 884.51kg shells, 150 per gun
   Breech loading guns in turret on barbette mounts, 1915 Model
   4 x Twin mounts on centreline ends, evenly spread
  2 raised mounts - superfiring
   1 x Twin mount on centreline, aft deck forward
      16 - 5.00" / 127 mm 45.0 cal guns - 65.00lbs / 29.48kg shells, 150 per gun
   Quick firing guns in deck and hoist mounts, 1915 Model
   16 x Single mounts on sides, evenly spread
  4 raised mounts
      Weight of broadside 20,540 lbs / 9,317 kg

Armour:
   - Belts:  Width (max) Length (avg)  Height (avg)
 Main: 6.00" / 152 mm 520.00 ft / 158.50 m 17.00 ft / 5.18 m
 Ends: Unarmoured
   Main Belt covers 100 % of normal length

   - Torpedo Bulkhead:
  2.00" / 51 mm 520.00 ft / 158.50 m 26.50 ft / 8.08 m

   - Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
 Main: 9.00" / 229 mm 7.00" / 178 mm  9.00" / 229 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 9.00" / 229 mm,  Aft 0.00" / 0 mm

Machinery:
 Oil fired boilers, steam turbines, 
 Geared drive, 4 shafts, 134,829 shp / 100,582 Kw = 29.50 kts
 Range 6,500nm at 16.00 kts
 Bunker at max displacement = 3,845 tons

Complement:
 1,352 - 1,758

Cost:
 £4.656 million / $18.625 million

Distribution of weights at normal displacement:
 Armament: 2,807 tons, 7.4 %
 Armour: 10,160 tons, 27.0 %
    - Belts: 2,255 tons, 6.0 %
    - Torpedo bulkhead: 1,020 tons, 2.7 %
    - Armament: 3,303 tons, 8.8 %
    - Armour Deck: 3,365 tons, 8.9 %
    - Conning Tower: 218 tons, 0.6 %
 Machinery: 3,737 tons, 9.9 %
 Hull, fittings & equipment: 16,382 tons, 43.5 %
 Fuel, ammunition & stores: 4,602 tons, 12.2 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   62,036 lbs / 28,139 Kg = 36.8 x 15.0 " / 381 mm shells or 9.1 torpedoes
 Stability (Unstable if below 1.00): 1.15
 Metacentric height 6.7 ft / 2.1 m
 Roll period: 16.5 seconds
 Steadiness - As gun platform (Average = 50 %): 57 %
   - Recoil effect (Restricted arc if above 1.00): 0.97
 Seaboat quality  (Average = 1.00): 1.15

Hull form characteristics:
 Hull has low quarterdeck ,
   a ram bow and a cruiser stern
 Block coefficient (normal/deep): 0.610 / 0.615
 Length to Beam Ratio: 7.84 : 1
 'Natural speed' for length: 28.28 kts
 Power going to wave formation at top speed: 50 %
 Trim (Max stability = 0, Max steadiness = 100): 50
 Bow angle (Positive = bow angles forward): -3.00 degrees
 Stern overhang: -2.00 ft / -0.61 m
 Freeboard (% = length of deck as a percentage of waterline length):
    Fore end,  Aft end
    - Forecastle: 20.00 %,  33.00 ft / 10.06 m,  28.00 ft / 8.53 m
    - Forward deck: 30.00 %,  28.00 ft / 8.53 m,  25.00 ft / 7.62 m
    - Aft deck: 17.00 %,  25.00 ft / 7.62 m,  25.00 ft / 7.62 m
    - Quarter deck: 33.00 %,  19.00 ft / 5.79 m,  17.00 ft / 5.18 m
    - Average freeboard:  24.14 ft / 7.36 m

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 88.7 %
  - Above water (accommodation/working, high = better): 220.3 %
 Waterplane Area: 60,240 Square feet or 5,597 Square metres
 Displacement factor (Displacement / loading): 117 %
 Structure weight / hull surface area: 211 lbs/sq ft or 1,029 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.98
  - Longitudinal: 1.20
  - Overall: 1.00
 Hull space for machinery, storage, compartmentation is adequate
 Room for accommodation and workspaces is excellent