My anachronistic Mercury cruiser

I have planned to try some of the early British cruisers as anachronistic Springsharp designs. Tonight, I tried a Mercury design. This is an unarmoured 2nd Class Cruiser. My ship has 12-5in QF guns and 4-47mm (3pdr) QF guns. The speed is a pretty fast 24 knots. My ship would have twin funnels and a rather high flush deck. I had to raise the freeboard to help increase the roll period to over 13 seconds. This is the Springsharp report:

Mercury, anachronistic version, Great Britain 2nd Class Cruiser laid down 1906 (Engine 1908)

Displacement:
 3,473 t light; 3,640 t standard; 4,250 t normal; 4,738 t full load

Dimensions: Length overall / water x beam x draught
 318.21 ft / 315.00 ft x 46.00 ft x 21.00 ft (normal load)
 96.99 m / 96.01 m x 14.02 m  x 6.40 m

Armament:
      8 - 5.00" / 127 mm guns (4x2 guns), 62.50lbs / 28.35kg shells, 1906 Model
   Quick firing guns in deck mounts with hoists
   on centreline ends, evenly spread, 2 raised mounts - superfiring
      4 - 5.00" / 127 mm guns (2x2 guns), 62.50lbs / 28.35kg shells, 1906 Model
   Quick firing guns in deck mounts with hoists
   on side, all amidships
      4 - 1.85" / 47.0 mm guns in single mounts, 3.17lbs / 1.44kg shells, 1906 Model
   Quick firing guns in deck mounts with hoists
   on side, all amidships, all raised mounts - superfiring
 Weight of broadside 763 lbs / 346 kg
 Shells per gun, main battery: 180
 4 - 18.0" / 457.2 mm above water torpedoes

Machinery:
 Coal fired boilers, complex reciprocating steam engines, 
 Direct drive, 2 shafts, 21,380 ihp / 15,950 Kw = 24.00 kts
 Range 5,600nm at 12.00 kts
 Bunker at max displacement = 1,098 tons (100% coal)

Complement:
 263 - 342

Cost:
 £0.470 million / $1.880 million

Distribution of weights at normal displacement:
 Armament: 95 tons, 2.2 %
 Machinery: 1,918 tons, 45.1 %
 Hull, fittings & equipment: 1,460 tons, 34.3 %
 Fuel, ammunition & stores: 777 tons, 18.3 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   1,895 lbs / 859 Kg = 30.3 x 5.0 " / 127 mm shells or 0.5 torpedoes
 Stability (Unstable if below 1.00): 1.16
 Metacentric height 2.1 ft / 0.6 m
 Roll period: 13.5 seconds
 Steadiness - As gun platform (Average = 50 %): 100 %
   - Recoil effect (Restricted arc if above 1.00): 0.83
 Seaboat quality  (Average = 1.00): 1.67

Hull form characteristics:
 Hull has a flush deck
 Block coefficient: 0.489
 Length to Beam Ratio: 6.85 : 1
 'Natural speed' for length: 17.75 kts
 Power going to wave formation at top speed: 63 %
 Trim (Max stability = 0, Max steadiness = 100): 73
 Bow angle (Positive = bow angles forward): 3.00 degrees
 Stern overhang: 2.00 ft / 0.61 m
 Freeboard (% = measuring location as a percentage of overall length):
    - Stem:  23.00 ft / 7.01 m
    - Forecastle (20 %): 19.00 ft / 5.79 m
    - Mid (50 %):  19.00 ft / 5.79 m
    - Quarterdeck (15 %): 19.00 ft / 5.79 m
    - Stern:  19.00 ft / 5.79 m
    - Average freeboard: 19.32 ft / 5.89 m

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 163.5 %
  - Above water (accommodation/working, high = better): 113.1 %
 Waterplane Area: 9,557 Square feet or 888 Square metres
 Displacement factor (Displacement / loading): 91 %
 Structure weight / hull surface area: 76 lbs/sq ft or 369 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.82
  - Longitudinal: 5.56
  - Overall: 1.00
 Hull space for machinery, storage, compartmentation is cramped
 Room for accommodation and workspaces is adequate
 Ship has slow, easy roll, a good, steady gun platform
 Excellent seaboat, comfortable, can fire her guns in the heaviest weather