An anachronistic cruiser Inconstant

I wanted to design an anachronistic cruiser from the 1860's or 1870's. I chose the Inconstant, which was pretty amazing ship that was only broken up in 1956, after long service as a hulk. The Inconstant was originally an iron frigate, built to counter the American Wampanoag class ships. The Inconstant was designed by Sir Edward Reed and was completed in 1869. The original Inconstant was pretty fast, with a speed of 16.2 knots. My anachronistic Inconstant has a flush deck, four turrets, two with triple 7.6in guns and two with twin 7.6in guns, all distributed on the centerline at the same level. There are also 6-5.5in guns in casemates. My design has additional protection, as I gave it a 1in deck and torpedo bulkheads. The turrets and barbettes are 3in. This is the Springsharp report:

Inconstant, anachronistic version, Great Britain Cruiser laid down 1907

Displacement:
 4,928 t light; 5,198 t standard; 5,780 t normal; 6,245 t full load

Dimensions: Length overall / water x beam x draught
 348.05 ft / 345.00 ft x 50.00 ft x 25.50 ft (normal load)
 106.09 m / 105.16 m x 15.24 m  x 7.77 m

Armament:
      10 - 7.60" / 193 mm guns (4 mounts), 219.49lbs / 99.56kg shells, 1907 Model
   Breech loading guns in turrets (on barbettes)
   on centreline, evenly spread
   Aft Main mounts separated by engine room
      6 - 5.50" / 140 mm guns in single mounts, 83.19lbs / 37.73kg shells, 1907 Model
   Breech loading guns in casemate mounts 
   on side, all amidships
   6 guns in hull casemates - Limited use in heavy seas
 Weight of broadside 2,694 lbs / 1,222 kg
 Shells per gun, main battery: 100

Armour:
   - Belts:  Width (max) Length (avg)  Height (avg)
 Ends: Unarmoured

   - Torpedo Bulkhead:
  1.00" / 25 mm 170.00 ft / 51.82 m 25.50 ft / 7.77 m

   - Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
 Main: 3.00" / 76 mm 2.00" / 51 mm  3.00" / 76 mm
 2nd: 3.00" / 76 mm 3.00" / 76 mm  3.00" / 76 mm

   - Armour deck: 1.00" / 25 mm, Conning tower: 3.00" / 76 mm

Machinery:
 Coal fired boilers, complex reciprocating steam engines, 
 Direct drive, 2 shafts, 15,693 ihp / 11,707 Kw = 21.50 kts
 Range 4,300nm at 12.00 kts
 Bunker at max displacement = 1,047 tons (100% coal)

Complement:
 330 - 430

Cost:
 £0.699 million / $2.798 million

Distribution of weights at normal displacement:
 Armament: 337 tons, 5.8 %
 Armour: 748 tons, 12.9 %
    - Belts: 0 tons, 0.0 %
    - Torpedo bulkhead: 160 tons, 2.8 %
    - Armament: 361 tons, 6.3 %
    - Armour Deck: 205 tons, 3.6 %
    - Conning Tower: 21 tons, 0.4 %
 Machinery: 1,744 tons, 30.2 %
 Hull, fittings & equipment: 2,100 tons, 36.3 %
 Fuel, ammunition & stores: 852 tons, 14.7 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   2,992 lbs / 1,357 Kg = 13.6 x 7.6 " / 193 mm shells or 0.7 torpedoes
 Stability (Unstable if below 1.00): 1.20
 Metacentric height 2.5 ft / 0.8 m
 Roll period: 13.4 seconds
 Steadiness - As gun platform (Average = 50 %): 52 %
   - Recoil effect (Restricted arc if above 1.00): 0.91
 Seaboat quality  (Average = 1.00): 1.30

Hull form characteristics:
 Hull has a flush deck
 Block coefficient: 0.460
 Length to Beam Ratio: 6.90 : 1
 'Natural speed' for length: 18.57 kts
 Power going to wave formation at top speed: 53 %
 Trim (Max stability = 0, Max steadiness = 100): 40
 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:  20.00 ft / 6.10 m
    - Forecastle (20 %): 16.00 ft / 4.88 m
    - Mid (50 %):  16.00 ft / 4.88 m
    - Quarterdeck (15 %): 16.00 ft / 4.88 m
    - Stern:  16.00 ft / 4.88 m
    - Average freeboard: 16.32 ft / 4.97 m
 Ship tends to be wet forward

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 234.9 %
  - Above water (accommodation/working, high = better): 102.5 %
 Waterplane Area: 11,094 Square feet or 1,031 Square metres
 Displacement factor (Displacement / loading): 83 %
 Structure weight / hull surface area: 104 lbs/sq ft or 508 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.89
  - Longitudinal: 3.02
  - Overall: 1.00
 Hull space for machinery, storage, compartmentation is extremely poor
 Room for accommodation and workspaces is adequate
 Good seaboat, rides out heavy weather easily