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Tuesday, February 01, 2005

Cliff's GB/CS/1915 ended up having to be very light

I tried to keep the dimensions and armament as my friend Cliff had specified in 1971, but the displacement had to drop dramatically, to achieve acceptable seakeeping ability. I don't see any indication that he wanted armor, which is a good thing, as there doesn't seem to be room for it. Cliff had wanted the design to have 800 tons of oil fuel, but the best I could do was to have 409 tons, still good for 7,500nm at 15 knots. That is pretty good for such a small ship. The armament is 4-6in QF and 4-21in TT. The speed of 32 knots was easy. Cliff had specifed 40,000 SHP and the Springsharp number of 40,848 SHP seems quite close to that figure. The machinery is about 36 SHP/ton, which is not unreasonable, as the British thought that they could do better than that for small, fast ships in 1905.
GB/CS/1915, Great Britain Scout Cruiser laid down 1915 (Engine 1933)

Displacement:
	2,038 t light; 2,132 t standard; 2,541 t normal; 2,868 t full load

Dimensions: Length overall / water x beam x draught
	408.31 ft / 405.00 ft x 41.00 ft x 13.00 ft (normal load)
	124.45 m / 123.44 m x 12.50 m  x 3.96 m

Armament:
      4 - 6.00" / 152 mm guns in single mounts, 108.00lbs / 48.99kg shells, 1915 Model
	  Quick firing guns in deck mounts with hoists
	  on centreline ends, evenly spread
	Weight of broadside 432 lbs / 196 kg
	Shells per gun, main battery: 180
	4 - 21.0" / 533.4 mm above water torpedoes

Machinery:
	Oil fired boilers, steam turbines, 
	Geared drive, 4 shafts, 40,848 shp / 30,472 Kw = 32.00 kts
	Range 7,500nm at 15.00 kts
	Bunker at max displacement = 736 tons

Complement:
	178 - 232

Cost:
	£0.400 million / $1.601 million

Distribution of weights at normal displacement:
	Armament: 54 tons, 2.1 %
	Machinery: 1,132 tons, 44.6 %
	Hull, fittings & equipment: 852 tons, 33.5 %
	Fuel, ammunition & stores: 503 tons, 19.8 %
	Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
	Survivability (Non-critical penetrating hits needed to sink ship):
	  1,141 lbs / 518 Kg = 10.6 x 6.0 " / 152 mm shells or 0.4 torpedoes
	Stability (Unstable if below 1.00): 1.52
	Metacentric height 2.7 ft / 0.8 m
	Roll period: 10.5 seconds
	Steadiness	- As gun platform (Average = 50 %): 54 %
			- Recoil effect (Restricted arc if above 1.00): 0.29
	Seaboat quality  (Average = 1.00): 1.04

Hull form characteristics:
	Hull has raised forecastle, rise forward of midbreak
	Block coefficient: 0.412
	Length to Beam Ratio: 9.88 : 1
	'Natural speed' for length: 20.12 kts
	Power going to wave formation at top speed: 62 %
	Trim (Max stability = 0, Max steadiness = 100): 52
	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:		25.00 ft / 7.62 m
	   - Forecastle (0 %):	17.00 ft / 5.18 m (16.00 ft / 4.88 m aft of break)
	   - Mid (0 %):		16.00 ft / 4.88 m (15.00 ft / 4.57 m aft of break)
	   - Quarterdeck (15 %):	15.00 ft / 4.57 m
	   - Stern:		15.00 ft / 4.57 m
	   - Average freeboard:	15.00 ft / 4.57 m

Ship space, strength and comments:
	Space	- Hull below water (magazines/engines, low = better): 160.6 %
		- Above water (accommodation/working, high = better): 137.8 %
	Waterplane Area: 10,297 Square feet or 957 Square metres
	Displacement factor (Displacement / loading): 90 %
	Structure weight / hull surface area: 48 lbs/sq ft or 236 Kg/sq metre
	Hull strength (Relative):
		- Cross-sectional: 0.63
		- Longitudinal: 1.41
		- Overall: 0.69
	Hull space for machinery, storage, compartmentation is cramped
	Room for accommodation and workspaces is excellent

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