My friend Cliff's GB/FG/1913 design

My friend Cliff had this concept for a fast gunboat to be laid down in 1913. He was casting around for a name and decided to call it a "Frigate-Gunboat". This is a ship that would have 5-4in QF guns and 2-21in TT. The speed was 32 knots, but he wanted a 20 knot cruising speed with 300 tons of oil fuel. This is the complete specification:

FG  1200 tons standard  32 knots   GB/FG/1913

300 tons oil fuel max.  5-4in QF guns and 2-21in TT
Dimensions: 315ft x 30ft x 10ft  25,000 SHP

V/sqrt(L) = 1.795  13ehp/ton  15,688 ehp = 32 knots
                              26,000 SHP = 32 knots
V/sqrt(L) = 1.12f   4 ehp/ton  4,800 ehp = 20 knots
                               8,000 SHP = 20 knots

This is the Springsharp report:

GB/FG/1913, Great Britain Frigate-Gunboat laid down 1913 (Engine 1950)

Displacement:
 1,124 t light; 1,167 t standard; 1,337 t normal; 1,472 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
 (317.82 ft / 315.00 ft) x 30.00 ft x (10.00 / 10.76 ft)
 (96.87 m / 96.01 m) x 9.14 m  x (3.05 / 3.28 m)

Armament:
      5 - 4.00" / 102 mm 45.0 cal guns - 32.00lbs / 14.51kg shells, 150 per gun
   Quick firing guns in deck and hoist mounts, 1913 Model
   4 x Single mounts on centreline ends, evenly spread
  2 raised mounts - superfiring
   1 x Single mount on centreline, forward deck aft
      Weight of broadside 160 lbs / 73 kg
      2 - 21.0" / 533 mm, 21.00 ft / 6.40 m torpedoes - 1.334 t each, 2.668 t total
 In 1 sets of deck mounted carriage/fixed tubes

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

Machinery:
 Oil fired boilers, steam turbines, 
 Direct drive, 2 shafts, 32,631 shp / 24,343 Kw = 32.00 kts
 Range 2,400nm at 20.00 kts
 Bunker at max displacement = 305 tons

Complement:
 109 - 143

Cost:
 £0.157 million / $0.627 million

Distribution of weights at normal displacement:
 Armament: 47 tons, 3.5 %
    - Guns: 45 tons, 3.3 %
    - Torpedoes: 3 tons, 0.2 %
 Armour: 67 tons, 5.0 %
    - Armament: 67 tons, 5.0 %
 Machinery: 634 tons, 47.4 %
 Hull, fittings & equipment: 377 tons, 28.2 %
 Fuel, ammunition & stores: 212 tons, 15.9 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   397 lbs / 180 Kg = 12.4 x 4.0 " / 102 mm shells or 0.3 torpedoes
 Stability (Unstable if below 1.00): 1.11
 Metacentric height 1.0 ft / 0.3 m
 Roll period: 12.6 seconds
 Steadiness - As gun platform (Average = 50 %): 53 %
   - Recoil effect (Restricted arc if above 1.00): 0.54
 Seaboat quality  (Average = 1.00): 1.06

Hull form characteristics:
 Hull has rise forward of midbreak,
   a normal bow and a round stern
 Block coefficient (normal/deep): 0.495 / 0.507
 Length to Beam Ratio: 10.50 : 1
 'Natural speed' for length: 17.75 kts
 Power going to wave formation at top speed: 70 %
 Trim (Max stability = 0, Max steadiness = 100): 50
 Bow angle (Positive = bow angles forward): 7.00 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 %,  23.00 ft / 7.01 m,  21.00 ft / 6.40 m
    - Forward deck: 15.00 %,  21.00 ft / 6.40 m,  21.00 ft / 6.40 m
    - Aft deck: 50.00 %,  13.00 ft / 3.96 m,  13.00 ft / 3.96 m
    - Quarter deck: 15.00 %,  13.00 ft / 3.96 m,  13.00 ft / 3.96 m
    - Average freeboard:  15.96 ft / 4.86 m

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 164.0 %
  - Above water (accommodation/working, high = better): 160.7 %
 Waterplane Area: 6,268 Square feet or 582 Square metres
 Displacement factor (Displacement / loading): 75 %
 Structure weight / hull surface area: 28 lbs/sq ft or 136 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.42
  - Longitudinal: 2.54
  - Overall: 0.51
 Hull space for machinery, storage, compartmentation is cramped
 Room for accommodation and workspaces is excellent