A 1910 fast British armoured cruiser

This morning I wondered what a 1910 fast British armoured cruiser would be like. I ran a Springsharp design that increased the armour and speed, but not the armament. At almost 20,000 tons, a ship with 8-9.2in and 16-4in guns seems underarmed. The speed is nice, at 29 knots. The range is 5,400 nm, which should be adequate. This is the Springsharp report:

GB/CA/1910, Great Britain Armoured Cruiser laid down 1910

Displacement:
 17,401 t light; 18,048 t standard; 19,800 t normal; 21,202 t full load

Dimensions: Length overall / water x beam x draught
 605.00 ft / 605.00 ft x 84.00 ft x 25.00 ft (normal load)
 184.40 m / 184.40 m x 25.60 m  x 7.62 m

Armament:
      8 - 9.20" / 234 mm guns (4x2 guns), 389.34lbs / 176.60kg shells, 1910 Model
   Breech loading guns in turrets (on barbettes)
   on centreline ends, evenly spread, 2 raised mounts - superfiring
      16 - 4.00" / 102 mm guns in single mounts, 32.00lbs / 14.51kg shells, 1910 Model
   Quick firing guns in casemate mounts 
   on side, evenly spread, 4 raised mounts
 Weight of broadside 3,627 lbs / 1,645 kg
 Shells per gun, main battery: 120

Armour:
   - Belts:  Width (max) Length (avg)  Height (avg)
 Main: 8.00" / 203 mm 420.00 ft / 128.02 m 17.00 ft / 5.18 m
 Ends: Unarmoured
   Main Belt covers 107 % of normal length

   - Torpedo Bulkhead:
  1.50" / 38 mm 420.00 ft / 128.02 m 23.00 ft / 7.01 m

   - Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
 Main: 8.00" / 203 mm 5.00" / 127 mm  8.00" / 203 mm
 2nd: 4.00" / 102 mm 4.00" / 102 mm  4.00" / 102 mm

   - Armour deck: 3.00" / 76 mm, Conning tower: 8.00" / 203 mm

Machinery:
 Oil fired boilers, steam turbines, 
 Direct drive, 4 shafts, 91,854 shp / 68,523 Kw = 29.00 kts
 Range 5,400nm at 15.00 kts
 Bunker at max displacement = 3,154 tons

Complement:
 833 - 1,084

Cost:
 £1.521 million / $6.085 million

Distribution of weights at normal displacement:
 Armament: 453 tons, 2.3 %
 Armour: 6,229 tons, 31.5 %
    - Belts: 2,426 tons, 12.3 %
    - Torpedo bulkhead: 536 tons, 2.7 %
    - Armament: 1,181 tons, 6.0 %
    - Armour Deck: 1,960 tons, 9.9 %
    - Conning Tower: 126 tons, 0.6 %
 Machinery: 3,796 tons, 19.2 %
 Hull, fittings & equipment: 6,923 tons, 35.0 %
 Fuel, ammunition & stores: 2,399 tons, 12.1 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   29,460 lbs / 13,363 Kg = 75.7 x 9.2 " / 234 mm shells or 4.3 torpedoes
 Stability (Unstable if below 1.00): 1.23
 Metacentric height 5.6 ft / 1.7 m
 Roll period: 14.9 seconds
 Steadiness - As gun platform (Average = 50 %): 59 %
   - Recoil effect (Restricted arc if above 1.00): 0.30
 Seaboat quality  (Average = 1.00): 1.19

Hull form characteristics:
 Hull has rise forward of midbreak
 Block coefficient: 0.545
 Length to Beam Ratio: 7.20 : 1
 'Natural speed' for length: 24.60 kts
 Power going to wave formation at top speed: 57 %
 Trim (Max stability = 0, Max steadiness = 100): 50
 Bow angle (Positive = bow angles forward): -2.00 degrees
 Stern overhang: -2.00 ft / -0.61 m
 Freeboard (% = measuring location as a percentage of overall length):
    - Stem:  29.00 ft / 8.84 m
    - Forecastle (20 %): 25.00 ft / 7.62 m
    - Mid (67 %):  25.00 ft / 7.62 m (17.00 ft / 5.18 m aft of break)
    - Quarterdeck (15 %): 17.00 ft / 5.18 m
    - Stern:  17.00 ft / 5.18 m
    - Average freeboard: 22.68 ft / 6.91 m

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 105.3 %
  - Above water (accommodation/working, high = better): 184.0 %
 Waterplane Area: 35,316 Square feet or 3,281 Square metres
 Displacement factor (Displacement / loading): 113 %
 Structure weight / hull surface area: 133 lbs/sq ft or 652 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.95
  - Longitudinal: 1.54
  - Overall: 1.00
 Hull space for machinery, storage, compartmentation is adequate
 Room for accommodation and workspaces is excellent