One of Walker's big frigates as an anachronistic cruiser

This is my anachronistic design for the Diadem, using the dimensions of one of Walker's big frigates laid down in 1855. Admittedly, it is a strange concept. I was surprised, again, how much good could be done within the scope of Springsharp. I was able to make a 20 knot convoy cruiser with a 3in protective deck. The cruising speed is a substantial 15 knots with a cruising range of 5,250 nm. The armament is 4-7.5in BLR, 12-4.7in QF, and 8-6pdr QF guns. There is a 1in anti-torpedo bulkhead. The ship would seem to be an adequate convoy surface escort. We might like a higher top end speed, but otherwise, it is acceptable. Others may not have a taste for such a thing, and I can understand that. This is the Springsharp report:

HMS Diadem, Great Britain Cruiser laid down 1910

Displacement:
 2,998 t light; 3,168 t standard; 3,880 t normal; 4,450 t full load

Dimensions: Length overall / water x beam x draught
 258.47 ft / 255.00 ft x 48.00 ft x 20.50 ft (normal load)
 78.78 m / 77.72 m x 14.63 m  x 6.25 m

Armament:
      4 - 7.50" / 191 mm guns (2x2 guns), 210.94lbs / 95.68kg shells, 1910 Model
   Breech loading guns in turrets (on barbettes)
   on centreline ends, evenly spread
      12 - 4.70" / 119 mm guns (6x2 guns), 51.91lbs / 23.55kg shells, 1910 Model
   Quick firing guns in turrets (on barbettes)
   on side ends, evenly spread, 2 raised mounts - superfiring
      8 - 2.24" / 57.0 mm guns in single mounts, 5.65lbs / 2.56kg shells, 1910 Model
   Quick firing guns in deck mounts 
   on side, evenly spread, all raised mounts
 Weight of broadside 1,512 lbs / 686 kg
 Shells per gun, main battery: 100

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

   - Torpedo Bulkhead:
  1.00" / 25 mm 200.00 ft / 60.96 m 19.00 ft / 5.79 m

   - Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
 Main: 3.00" / 76 mm 3.00" / 76 mm  4.00" / 102 mm
 2nd: 2.00" / 51 mm 2.00" / 51 mm  2.00" / 51 mm
 3rd: 1.00" / 25 mm       -         -

   - Armour deck: 3.00" / 76 mm, Conning tower: 5.00" / 127 mm

Machinery:
 Oil fired boilers, steam turbines, 
 Direct drive, 2 shafts, 11,199 shp / 8,355 Kw = 20.00 kts
 Range 5,250nm at 15.00 kts
 Bunker at max displacement = 1,282 tons

Complement:
 245 - 319

Cost:
 £0.328 million / $1.314 million

Distribution of weights at normal displacement:
 Armament: 189 tons, 4.9 %
 Armour: 965 tons, 24.9 %
    - Belts: 0 tons, 0.0 %
    - Torpedo bulkhead: 141 tons, 3.6 %
    - Armament: 327 tons, 8.4 %
    - Armour Deck: 470 tons, 12.1 %
    - Conning Tower: 27 tons, 0.7 %
 Machinery: 463 tons, 11.9 %
 Hull, fittings & equipment: 1,382 tons, 35.6 %
 Fuel, ammunition & stores: 882 tons, 22.7 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   5,126 lbs / 2,325 Kg = 24.3 x 7.5 " / 191 mm shells or 1.5 torpedoes
 Stability (Unstable if below 1.00): 1.01
 Metacentric height 1.7 ft / 0.5 m
 Roll period: 15.5 seconds
 Steadiness - As gun platform (Average = 50 %): 53 %
   - Recoil effect (Restricted arc if above 1.00): 0.92
 Seaboat quality  (Average = 1.00): 1.05

Hull form characteristics:
 Hull has a flush deck
 Block coefficient: 0.541
 Length to Beam Ratio: 5.31 : 1
 'Natural speed' for length: 15.97 kts
 Power going to wave formation at top speed: 64 %
 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:  21.00 ft / 6.40 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: 16.40 ft / 5.00 m

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 130.1 %
  - Above water (accommodation/working, high = better): 105.4 %
 Waterplane Area: 8,472 Square feet or 787 Square metres
 Displacement factor (Displacement / loading): 114 %
 Structure weight / hull surface area: 95 lbs/sq ft or 464 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.85
  - Longitudinal: 4.72
  - Overall: 1.00
 Hull space for machinery, storage, compartmentation is cramped
 Room for accommodation and workspaces is adequate