My 1921-style light cruiser with lightweight machinery

Blogger has been down for a number of hours, so I have tried to post about my 1921 British light cruiser design that is attempting to be a 35-knot ship with 6in guns. The E-class ships were a move in this direction. They had moderately light weight machinery, but had a lesser speed goal. I wanted a design with more of an edge, as there were the Japanese light cruisers and the US Omaha class in competition. I really wanted a 36-knot ship, but Springsharp would not accommodate light enough machinery. This is the Springsharp report:

GB/CL/1921, Great Britain Light Cruiser laid down 1921 (Engine 1950)

Displacement:
 6,398 t light; 6,620 t standard; 7,050 t normal; 7,394 t full load

Dimensions: Length overall / water x beam x draught
 558.75 ft / 555.00 ft x 55.00 ft x 18.00 ft (normal load)
 170.31 m / 169.16 m x 16.76 m  x 5.49 m

Armament:
      7 - 6.00" / 152 mm guns in single mounts, 108.00lbs / 48.99kg shells, 1921 Model
   Breech loading guns in deck mounts with hoists
   on centreline ends, majority forward
      4 - 4.00" / 102 mm guns in single mounts, 32.00lbs / 14.51kg shells, 1921 Model
   Anti-aircraft guns in deck mounts with hoists
   on side, all amidships
      16 - 1.57" / 40.0 mm guns (4x4 guns), 1.95lbs / 0.89kg shells, 1921 Model
   Anti-aircraft guns in deck mounts 
   on side, evenly spread
 Weight of broadside 915 lbs / 415 kg
 Shells per gun, main battery: 150
 4 - 21.0" / 533.4 mm above water torpedoes

Armour:
   - Belts:  Width (max) Length (avg)  Height (avg)
 Main: 2.00" / 51 mm 450.00 ft / 137.16 m 12.00 ft / 3.66 m
 Ends: Unarmoured
   Main Belt covers 125 % of normal length

   - Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
 Main: 4.00" / 102 mm       -   2.00" / 51 mm

   - Armour deck: 1.00" / 25 mm, Conning tower: 4.00" / 102 mm

Machinery:
 Oil fired boilers, steam turbines, 
 Geared drive, 4 shafts, 98,096 shp / 73,180 Kw = 35.00 kts
 Range 4,750nm at 15.00 kts
 Bunker at max displacement = 775 tons

Complement:
 384 - 500

Cost:
 £1.651 million / $6.604 million

Distribution of weights at normal displacement:
 Armament: 114 tons, 1.6 %
 Armour: 926 tons, 13.1 %
    - Belts: 433 tons, 6.1 %
    - Torpedo bulkhead: 0 tons, 0.0 %
    - Armament: 101 tons, 1.4 %
    - Armour Deck: 360 tons, 5.1 %
    - Conning Tower: 32 tons, 0.4 %
 Machinery: 2,347 tons, 33.3 %
 Hull, fittings & equipment: 3,010 tons, 42.7 %
 Fuel, ammunition & stores: 652 tons, 9.2 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   6,955 lbs / 3,155 Kg = 64.4 x 6.0 " / 152 mm shells or 1.1 torpedoes
 Stability (Unstable if below 1.00): 1.27
 Metacentric height 3.1 ft / 1.0 m
 Roll period: 13.1 seconds
 Steadiness - As gun platform (Average = 50 %): 52 %
   - Recoil effect (Restricted arc if above 1.00): 0.28
 Seaboat quality  (Average = 1.00): 1.04

Hull form characteristics:
 Hull has rise forward of midbreak
 Block coefficient: 0.449
 Length to Beam Ratio: 10.09 : 1
 'Natural speed' for length: 23.56 kts
 Power going to wave formation at top speed: 60 %
 Trim (Max stability = 0, Max steadiness = 100): 50
 Bow angle (Positive = bow angles forward): 4.00 degrees
 Stern overhang: 2.00 ft / 0.61 m
 Freeboard (% = measuring location as a percentage of overall length):
    - Stem:  25.00 ft / 7.62 m
    - Forecastle (20 %): 22.00 ft / 6.71 m
    - Mid (67 %):  22.00 ft / 6.71 m (14.00 ft / 4.27 m aft of break)
    - Quarterdeck (15 %): 14.00 ft / 4.27 m
    - Stern:  14.00 ft / 4.27 m
    - Average freeboard: 19.60 ft / 5.97 m
 Ship tends to be wet forward

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 120.6 %
  - Above water (accommodation/working, high = better): 173.7 %
 Waterplane Area: 19,456 Square feet or 1,808 Square metres
 Displacement factor (Displacement / loading): 108 %
 Structure weight / hull surface area: 92 lbs/sq ft or 448 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.94
  - Longitudinal: 1.67
  - Overall: 1.00
 Hull space for machinery, storage, compartmentation is cramped
 Room for accommodation and workspaces is excellent