The GB/PGL/1906 from 2001

In August 2001, I recast my friend Cliff's design for the GB/PGL/1906 to be more in line with practice circa 1906. It still has 3-5in QF guns, but none are superfiring. Instead there is one mount forward and two aft, all on the centerline. Given the vagaries of Springsharp, the design is only viable due to the lightest weight machinery. The dimensions are 340ft x 35ft x 12ft, as I increased the draft to improve the composite strength and seakeeping. This is the Springsharp report:

GB/PGL/1906, Great Britain Large Fast Gunboat laid down 1906 (Engine 1950)

Displacement:
 1,327 t light; 1,373 t standard; 1,500 t normal; 1,602 t full load

Dimensions: Length overall / water x beam x draught
 341.08 ft / 340.00 ft x 35.00 ft x 12.00 ft (normal load)
 103.96 m / 103.63 m x 10.67 m  x 3.66 m

Armament:
      3 - 5.00" / 127 mm guns in single mounts, 62.50lbs / 28.35kg shells, 1906 Model
   Quick firing guns in deck mounts with hoists
   on centreline, evenly spread
   Aft Main mounts separated by engine room
 Weight of broadside 188 lbs / 85 kg
 Shells per gun, main battery: 150

Machinery:
 Oil fired boilers, steam turbines, 
 Direct drive, 2 shafts, 45,870 shp / 34,219 Kw = 35.00 kts
 Range 3,600nm at 15.00 kts
 Bunker at max displacement = 229 tons

Complement:
 119 - 156

Cost:
 £0.177 million / $0.709 million

Distribution of weights at normal displacement:
 Armament: 23 tons, 1.6 %
 Machinery: 794 tons, 52.9 %
 Hull, fittings & equipment: 510 tons, 34.0 %
 Fuel, ammunition & stores: 173 tons, 11.5 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   416 lbs / 189 Kg = 6.7 x 5.0 " / 127 mm shells or 0.3 torpedoes
 Stability (Unstable if below 1.00): 1.34
 Metacentric height 1.7 ft / 0.5 m
 Roll period: 11.1 seconds
 Steadiness - As gun platform (Average = 50 %): 63 %
   - Recoil effect (Restricted arc if above 1.00): 0.30
 Seaboat quality  (Average = 1.00): 1.27

Hull form characteristics:
 Hull has rise forward of midbreak
 Block coefficient: 0.368
 Length to Beam Ratio: 9.71 : 1
 'Natural speed' for length: 18.44 kts
 Power going to wave formation at top speed: 69 %
 Trim (Max stability = 0, Max steadiness = 100): 50
 Bow angle (Positive = bow angles forward): 2.00 degrees
 Stern overhang: 0.00 ft / 0.00 m
 Freeboard (% = measuring location as a percentage of overall length):
    - Stem:  31.00 ft / 9.45 m
    - Forecastle (20 %): 28.00 ft / 8.53 m
    - Mid (33 %):  28.00 ft / 8.53 m (12.00 ft / 3.66 m aft of break)
    - Quarterdeck (15 %): 12.00 ft / 3.66 m
    - Stern:  12.00 ft / 3.66 m
    - Average freeboard: 17.52 ft / 5.34 m

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 182.8 %
  - Above water (accommodation/working, high = better): 175.9 %
 Waterplane Area: 7,230 Square feet or 672 Square metres
 Displacement factor (Displacement / loading): 63 %
 Structure weight / hull surface area: 31 lbs/sq ft or 153 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.42
  - Longitudinal: 3.47
  - Overall: 0.52
 Hull space for machinery, storage, compartmentation is cramped
 Room for accommodation and workspaces is excellent
 Good seaboat, rides out heavy weather easily