My friend Cliff's fast gunboat design: GB/PG/1915

My friend Cliff designed two ships with the same philosophy: flush-decked with superfiring guns. One was a scout cruiser and the other was a fast gunboat (no torpedo tubes). I struggled with Springsharp to ge adequate seakeeping ability, and untimately succeeded. The dimensions are those that Cliff originally planned:

GB/PG/1915, Great Britain Fast Gunboat laid down 1905 (Engine 1933)

Displacement:
	691 t light; 725 t standard; 785 t normal; 833 t full load

Dimensions: Length overall / water x beam x draught
	263.00 ft / 260.00 ft x 27.00 ft x 9.50 ft (normal load)
	80.16 m / 79.25 m x 8.23 m  x 2.90 m

Armament:
      4 - 4.00" / 102 mm guns in single mounts, 32.00lbs / 14.51kg shells, 1905 Model
	  Quick firing guns in deck mounts with hoists
	  on centreline ends, evenly spread, all raised mounts - superfiring
	Weight of broadside 128 lbs / 58 kg
	Shells per gun, main battery: 250

Machinery:
	Oil fired boilers, steam turbines, 
	Geared drive, 2 shafts, 25,135 shp / 18,750 Kw = 32.00 kts
	Range 3,600nm at 12.00 kts
	Bunker at max displacement = 109 tons

Complement:
	73 - 96

Cost:
	£0.094 million / $0.376 million

Distribution of weights at normal displacement:
	Armament: 16 tons, 2.0 %
	Machinery: 403 tons, 51.4 %
	Hull, fittings & equipment: 272 tons, 34.6 %
	Fuel, ammunition & stores: 94 tons, 12.0 %
	Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
	Survivability (Non-critical penetrating hits needed to sink ship):
	  210 lbs / 95 Kg = 6.6 x 4.0 " / 102 mm shells or 0.2 torpedoes
	Stability (Unstable if below 1.00): 1.22
	Metacentric height 1.0 ft / 0.3 m
	Roll period: 11.3 seconds
	Steadiness	- As gun platform (Average = 50 %): 54 %
			- Recoil effect (Restricted arc if above 1.00): 0.68
	Seaboat quality  (Average = 1.00): 1.02

Hull form characteristics:
	Hull has a flush deck
	Block coefficient: 0.412
	Length to Beam Ratio: 9.63 : 1
	'Natural speed' for length: 16.12 kts
	Power going to wave formation at top speed: 72 %
	Trim (Max stability = 0, Max steadiness = 100): 53
	Bow angle (Positive = bow angles forward): 3.00 degrees
	Stern overhang: 2.00 ft / 0.61 m
	Freeboard (% = measuring location as a percentage of overall length):
	   - Stem:		19.00 ft / 5.79 m
	   - Forecastle (20 %):	14.00 ft / 4.27 m
	   - Mid (50 %):		14.00 ft / 4.27 m
	   - Quarterdeck (15 %):	14.00 ft / 4.27 m
	   - Stern:		14.00 ft / 4.27 m
	   - Average freeboard:	14.40 ft / 4.39 m

Ship space, strength and comments:
	Space	- Hull below water (magazines/engines, low = better): 182.4 %
		- Above water (accommodation/working, high = better): 159.0 %
	Waterplane Area: 4,353 Square feet or 404 Square metres
	Displacement factor (Displacement / loading): 49 %
	Structure weight / hull surface area: 26 lbs/sq ft or 127 Kg/sq metre
	Hull strength (Relative):
		- Cross-sectional: 0.40
		- Longitudinal: 4.12
		- Overall: 0.50
	Hull space for machinery, storage, compartmentation is cramped
	Room for accommodation and workspaces is excellent