An attempt at a faster Italian light cruiser: It/CL/1939 Fast

We will have trouble doing too much better than this with the current version of Springsharp 3.0b2 Beta. There may actually be two issues at work, not just the machinery weight. The other is the formula used to calculate power for a hull model to make a given speed. I have suspected that for smaller ships, what Springsharp is currently using requires too much power for a given speed. I base that on comparisons with real ships. We know, for example, that the Italian Capitani Romani class ships could make 41 knots on trials. I had to warp the design to get 35 knots:

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

Displacement:
 4,381 t light; 4,542 t standard; 4,917 t normal; 5,217 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
 (470.62 ft / 462.50 ft) x 47.25 ft x (17.50 / 18.25 ft)
 (143.44 m / 140.97 m) x 14.40 m  x (5.33 / 5.56 m)

Armament:
      8 - 5.30" / 135 mm 45.0 cal guns - 75.07lbs / 34.05kg shells, 150 per gun
   Dual purpose guns in turret on barbette mounts, 1939 Model
   4 x Single mounts on centreline ends, evenly spread
      8 - 1.46" / 37.0 mm 55.0 cal guns - 1.67lbs / 0.76kg shells, 150 per gun
   Breech loading guns in deck mounts, 1939 Model
   8 x Single mounts on sides, evenly spread
  8 raised mounts
      Weight of broadside 614 lbs / 278 kg
      8 - 21.0" / 533 mm, 21.00 ft / 6.40 m torpedoes - 1.438 t each, 11.504 t total
 In 2 sets of deck mounted carriage/fixed tubes

Armour:
   - Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
 Main: 0.70" / 18 mm 0.70" / 18 mm  0.70" / 18 mm

   - Conning towers: Forward 0.70" / 18 mm,  Aft 0.00" / 0 mm

Machinery:
 Oil fired boilers, steam turbines, 
 Geared drive, 2 shafts, 86,370 shp / 64,432 Kw = 35.00 kts
 Range 4,500nm at 16.00 kts
 Bunker at max displacement = 676 tons

Complement:
 293 - 381

Cost:
 £2.913 million / $11.653 million

Distribution of weights at normal displacement:
 Armament: 200 tons, 4.1 %
    - Guns: 189 tons, 3.8 %
    - Torpedoes: 12 tons, 0.2 %
 Armour: 53 tons, 1.1 %
    - Armament: 49 tons, 1.0 %
    - Conning Tower: 4 tons, 0.1 %
 Machinery: 2,066 tons, 42.0 %
 Hull, fittings & equipment: 2,061 tons, 41.9 %
 Fuel, ammunition & stores: 536 tons, 10.9 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   3,131 lbs / 1,420 Kg = 42.1 x 5.3 " / 135 mm shells or 0.7 torpedoes
 Stability (Unstable if below 1.00): 1.19
 Metacentric height 2.3 ft / 0.7 m
 Roll period: 13.2 seconds
 Steadiness - As gun platform (Average = 50 %): 53 %
   - Recoil effect (Restricted arc if above 1.00): 0.34
 Seaboat quality  (Average = 1.00): 1.03

Hull form characteristics:
 Hull has a flush deck,
   a normal bow and a round stern
 Block coefficient (normal/deep): 0.450 / 0.458
 Length to Beam Ratio: 9.79 : 1
 'Natural speed' for length: 21.51 kts
 Power going to wave formation at top speed: 65 %
 Trim (Max stability = 0, Max steadiness = 100): 51
 Bow angle (Positive = bow angles forward): 9.00 degrees
 Stern overhang: 4.00 ft / 1.22 m
 Freeboard (% = length of deck as a percentage of waterline length):
    Fore end,  Aft end
    - Forecastle: 22.00 %,  26.00 ft / 7.92 m,  21.00 ft / 6.40 m
    - Forward deck: 30.00 %,  21.00 ft / 6.40 m,  18.00 ft / 5.49 m
    - Aft deck: 33.00 %,  18.00 ft / 5.49 m,  18.00 ft / 5.49 m
    - Quarter deck: 15.00 %,  18.00 ft / 5.49 m,  18.00 ft / 5.49 m
    - Average freeboard:  19.55 ft / 5.96 m

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 146.9 %
  - Above water (accommodation/working, high = better): 166.0 %
 Waterplane Area: 13,939 Square feet or 1,295 Square metres
 Displacement factor (Displacement / loading): 104 %
 Structure weight / hull surface area: 81 lbs/sq ft or 398 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.89
  - Longitudinal: 2.87
  - Overall: 1.00
 Hull space for machinery, storage, compartmentation is cramped
 Room for accommodation and workspaces is excellent