My anachronistic HMS Southampton

I have this drawing that calls itself the HMS Southampton. It has a flush deck and twin funnels with a block superstructure. There are 3-triple turrets with 6in guns. It has torpedo tubes on the deck and a light AA armament. It actually works quite well. I actually can't understand why! I suppose it is the modest speed:

HMS Southampton, Great Britain Light Cruiser laid down 1911

Displacement:
 4,699 t light; 4,867 t standard; 5,441 t normal; 5,900 t full load

Dimensions: Length overall / water x beam x draught
 455.70 ft / 454.00 ft x 50.00 ft x 16.00 ft (normal load)
 138.90 m / 138.38 m x 15.24 m  x 4.88 m

Armament:
      9 - 6.00" / 152 mm guns (3x3 guns), 108.00lbs / 48.99kg shells, 1911 Model
   Breech loading guns in turrets (on barbettes)
   on centreline ends, majority forward, 1 raised mount - superfiring
      4 - 4.00" / 102 mm guns (2x2 guns), 32.00lbs / 14.51kg shells, 1911 Model
   Anti-aircraft guns in turrets (on barbettes)
   on side, all amidships, all raised mounts - superfiring
      20 - 1.57" / 40.0 mm guns (5x4 guns), 1.95lbs / 0.89kg shells, 1911 Model
   Anti-aircraft guns in deck mounts 
   on side, evenly spread, 4 raised mounts
 Weight of broadside 1,139 lbs / 517 kg
 Shells per gun, main battery: 90
 4 - 21.0" / 533.4 mm above water torpedoes

Armour:
   - Belts:  Width (max) Length (avg)  Height (avg)
 Main: 4.00" / 102 mm 310.00 ft / 94.49 m 16.00 ft / 4.88 m
 Ends: Unarmoured
   Main Belt covers 105 % of normal length

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

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

Machinery:
 Oil fired boilers, steam turbines, 
 Direct drive, 2 shafts, 24,544 shp / 18,310 Kw = 25.00 kts
 Range 6,700nm at 12.00 kts
 Bunker at max displacement = 1,033 tons

Complement:
 316 - 411

Cost:
 £0.424 million / $1.694 million

Distribution of weights at normal displacement:
 Armament: 142 tons, 2.6 %
 Armour: 1,583 tons, 29.1 %
    - Belts: 827 tons, 15.2 %
    - Torpedo bulkhead: 0 tons, 0.0 %
    - Armament: 157 tons, 2.9 %
    - Armour Deck: 572 tons, 10.5 %
    - Conning Tower: 27 tons, 0.5 %
 Machinery: 996 tons, 18.3 %
 Hull, fittings & equipment: 1,977 tons, 36.3 %
 Fuel, ammunition & stores: 742 tons, 13.6 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   7,825 lbs / 3,549 Kg = 72.4 x 6.0 " / 152 mm shells or 1.5 torpedoes
 Stability (Unstable if below 1.00): 1.24
 Metacentric height 2.6 ft / 0.8 m
 Roll period: 13.0 seconds
 Steadiness - As gun platform (Average = 50 %): 58 %
   - Recoil effect (Restricted arc if above 1.00): 0.40
 Seaboat quality  (Average = 1.00): 1.15

Hull form characteristics:
 Hull has a flush deck
 Block coefficient: 0.524
 Length to Beam Ratio: 9.08 : 1
 'Natural speed' for length: 21.31 kts
 Power going to wave formation at top speed: 52 %
 Trim (Max stability = 0, Max steadiness = 100): 50
 Bow angle (Positive = bow angles forward): 2.00 degrees
 Stern overhang: 1.00 ft / 0.30 m
 Freeboard (% = measuring location as a percentage of overall length):
    - Stem:  20.00 ft / 6.10 m
    - Forecastle (20 %): 13.00 ft / 3.96 m
    - Mid (50 %):  13.00 ft / 3.96 m
    - Quarterdeck (15 %): 13.00 ft / 3.96 m
    - Stern:  13.00 ft / 3.96 m
    - Average freeboard: 13.56 ft / 4.13 m
 Ship tends to be wet forward

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 79.5 %
  - Above water (accommodation/working, high = better): 106.5 %
 Waterplane Area: 15,467 Square feet or 1,437 Square metres
 Displacement factor (Displacement / loading): 115 %
 Structure weight / hull surface area: 85 lbs/sq ft or 416 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.98
  - Longitudinal: 1.18
  - Overall: 1.00
 Hull space for machinery, storage, compartmentation is excellent
 Room for accommodation and workspaces is adequate