A It/CL/1939 design study

I thought that the time was right to see what might be done for a fast Italian light cruiser, along the lines of the Capitani Romani class, but not that closely aligned with that specification. My design study was for a 462.5ft long ship with 8-5.3in guns and 8-21in TT. I was able to achieve 38 knots with the design:

It/CL/1939, Italy Light Cruiser laid down 1939 (Engine 1950)

Displacement:
 3,696 t light; 3,839 t standard; 4,040 t normal; 4,201 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
 (468.45 ft / 462.50 ft) x 43.00 ft x (18.00 / 18.46 ft)
 (142.78 m / 140.97 m) x 13.11 m  x (5.49 / 5.63 m)

Armament:
      8 - 5.30" / 135 mm 45.0 cal guns - 75.07lbs / 34.05kg shells, 150 per gun
   Breech loading guns in turret on barbette mounts, 1939 Model
   4 x Single mounts on centreline ends, evenly spread
  4 raised mounts
      Weight of broadside 601 lbs / 272 kg
      8 - 21.0" / 533 mm, 22.00 ft / 6.71 m torpedoes - 1.497 t each, 11.977 t total
 In 2 sets of deck mounted side rotating tubes

Armour:
   - Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
 Main: 1.00" / 25 mm 1.00" / 25 mm  1.00" / 25 mm

Machinery:
 Oil fired boilers, steam turbines, 
 Geared drive, 4 shafts, 103,050 shp / 76,875 Kw = 38.00 kts
 Range 3,500nm at 14.00 kts
 Bunker at max displacement = 362 tons

Complement:
 253 - 329

Cost:
 £2.974 million / $11.894 million

Distribution of weights at normal displacement:
 Armament: 185 tons, 4.6 %
    - Guns: 173 tons, 4.3 %
    - Torpedoes: 12 tons, 0.3 %
 Armour: 80 tons, 2.0 %
    - Armament: 80 tons, 2.0 %
 Machinery: 2,319 tons, 57.4 %
 Hull, fittings & equipment: 1,112 tons, 27.5 %
 Fuel, ammunition & stores: 344 tons, 8.5 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   800 lbs / 363 Kg = 10.7 x 5.3 " / 135 mm shells or 0.4 torpedoes
 Stability (Unstable if below 1.00): 1.19
 Metacentric height 1.9 ft / 0.6 m
 Roll period: 13.0 seconds
 Steadiness - As gun platform (Average = 50 %): 61 %
   - Recoil effect (Restricted arc if above 1.00): 0.65
 Seaboat quality  (Average = 1.00): 1.22

Hull form characteristics:
 Hull has a flush deck,
   an extended bulbous bow and a cruiser stern
 Block coefficient (normal/deep): 0.395 / 0.400
 Length to Beam Ratio: 10.76 : 1
 'Natural speed' for length: 21.51 kts
 Power going to wave formation at top speed: 66 %
 Trim (Max stability = 0, Max steadiness = 100): 50
 Bow angle (Positive = bow angles forward): 12.00 degrees
 Stern overhang: 0.00 ft / 0.00 m
 Freeboard (% = length of deck as a percentage of waterline length):
    Fore end,  Aft end
    - Forecastle: 20.00 %,  28.00 ft / 8.53 m,  24.00 ft / 7.32 m
    - Forward deck: 30.00 %,  24.00 ft / 7.32 m,  20.00 ft / 6.10 m
    - Aft deck: 35.00 %,  20.00 ft / 6.10 m,  17.00 ft / 5.18 m
    - Quarter deck: 15.00 %,  17.00 ft / 5.18 m,  17.00 ft / 5.18 m
    - Average freeboard:  20.75 ft / 6.32 m

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 198.1 %
  - Above water (accommodation/working, high = better): 176.7 %
 Waterplane Area: 12,201 Square feet or 1,133 Square metres
 Displacement factor (Displacement / loading): 73 %
 Structure weight / hull surface area: 44 lbs/sq ft or 215 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.44
  - Longitudinal: 2.30
  - Overall: 0.52
 Caution: Hull subject to strain in open-sea
 Hull space for machinery, storage, compartmentation is cramped
 Room for accommodation and workspaces is excellent
 Good seaboat, rides out heavy weather easily