My anachornistic Mersey screw frigate design

I have this pencil drawing from the 1980's of an anachronistic Mersey screw frigate design:

Amazingly enough, this design works well in Springsharp. The armament is 7-7in/45 BLR and 6-5.5in/45 BLR guns. The protection is mainly a 2in deck, with the guns protected, as well as there being a 1in torpedo bulkhead. The speed is decent, at 21 knots. The cruising speed is high, at 15 knots, as that helps the recoil issue, as well as stability. This is the Springsharp 3.0b1 Beta report:

Mersey, anachronistic, Great Britain Cruiser (screw frigate) laid down 1907 (Engine 1909)

Displacement:
 4,353 t light; 4,608 t standard; 5,640 t normal; 6,467 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
 (345.00 ft / 345.00 ft) x 52.00 ft x (21.00 / 23.45 ft)
 (105.16 m / 105.16 m) x 15.85 m  x (6.40 / 7.15 m)

Armament:
      7 - 7.00" / 178 mm 45.0 cal guns - 170.00lbs / 77.11kg shells, 150 per gun
   Breech loading guns in turret on barbette mounts , 1907 Model
   2 x Twin mounts on centreline, forward deck forward
  1 raised mount - superfiring
   1 x Triple mount on centreline, aft deck aft
      6 - 5.50" / 140 mm 45.0 cal guns - 85.00lbs / 38.56kg shells, 150 per gun
   Breech loading guns in turret on barbette mounts , 1907 Model
   2 x Twin mounts on sides, forward deck aft
   1 x Twin mount on centreline, aft deck forward
  1 raised mount
 Weight of broadside 1,700 lbs / 1,700 kg

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

   - Torpedo Bulkhead:
  1.00" / 25 mm 225.00 ft / 68.58 m 21.00 ft / 6.40 m

   - Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
 Main: 4.00" / 102 mm 3.00" / 76 mm  4.00" / 102 mm
 2nd: 4.00" / 102 mm 3.00" / 76 mm  4.00" / 102 mm

   - Armour deck: 2.00" / 51 mm, Conning tower: 4.00" / 102 mm

Machinery:
 Coal fired boilers, complex reciprocating steam engines, 
 Direct drive, 1 shaft, 14,417 ihp / 10,755 Kw = 21.00 kts
 Range 4,700nm at 15.00 kts
 Bunker at max displacement = 1,859 tons (100% coal)

Complement:
 325 - 423

Cost:
 £0.469 million / $1.877 million

Distribution of weights at normal displacement:
 Armament: 389 tons, 6.9 %
 Armour: 1,073 tons, 19.0 %
    - Belts: 0 tons, 0.0 %
    - Torpedo bulkhead: 175 tons, 3.1 %
    - Armament: 435 tons, 7.7 %
    - Armour Deck: 436 tons, 7.7 %
    - Conning Tower: 27 tons, 0.5 %
 Machinery: 1,109 tons, 19.7 %
 Hull, fittings & equipment: 1,978 tons, 35.1 %
 Fuel, ammunition & stores: 1,287 tons, 22.8 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   6,315 lbs / 2,864 Kg = 36.8 x 7.0 " / 178 mm shells or 1.4 torpedoes
 Stability (Unstable if below 1.00): 1.13
 Metacentric height 2.4 ft / 0.7 m
 Roll period: 14.2 seconds
 Steadiness - As gun platform (Average = 50 %): 63 %
   - Recoil effect (Restricted arc if above 1.00): 0.72
 Seaboat quality  (Average = 1.00): 1.27

Hull form characteristics:
 Hull has a flush deck,
   a normal bow and a round stern
 Block coefficient (normal/deep): 0.524 / 0.538
 Length to Beam Ratio: 6.63 : 1
 'Natural speed' for length: 18.57 kts
 Power going to wave formation at top speed: 55 %
 Trim (Max stability = 0, Max steadiness = 100): 50
 Bow angle (Positive = bow angles forward): 0.00 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 %,  18.00 ft / 5.49 m,  16.00 ft / 4.88 m
    - Forward deck: 30.00 %,  16.00 ft / 4.88 m,  15.00 ft / 4.57 m
    - Aft deck: 35.00 %,  15.00 ft / 4.57 m,  15.00 ft / 4.57 m
    - Quarter deck: 15.00 %,  15.00 ft / 4.57 m,  15.00 ft / 4.57 m
    - Average freeboard:  15.51 ft / 4.73 m
 Ship tends to be wet forward

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 147.5 %
  - Above water (accommodation/working, high = better): 105.3 %
 Waterplane Area: 11,797 Square feet or 1,096 Square metres
 Displacement factor (Displacement / loading): 117 %
 Structure weight / hull surface area: 100 lbs/sq ft or 489 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.90
  - Longitudinal: 2.57
  - Overall: 1.00
 Hull space for machinery, storage, compartmentation is cramped
 Room for accommodation and workspaces is adequate
 Good seaboat, rides out heavy weather easily