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Wednesday, January 05, 2005

To get the GB/CB/1905 up to the originally intended speed, the design had to be greatly inflated

I decided to see what it would take to get the GB/CB/1905 battlecruiser design up to at least 31 knots. The goal was to get the coveted "Design well balanced for a battleship or cruiser" rating. To do that, I had to inflate the displacement to 30,290 tons normal displacement. The standard displacement doesn't look so bad: 27,124 tons. This is the report, which has all the relevant details:
GB/CB/1905a2, Great Britain Battlecruiser laid down 1905 (Engine 1906)

Displacement:
	26,518 t light; 27,124 t standard; 30,290 t normal; 32,823 t full load

Dimensions: Length overall / water x beam x draught
	770.00 ft / 770.00 ft x 85.00 ft x 26.00 ft (normal load)
	234.70 m / 234.70 m x 25.91 m  x 7.92 m

Armament:
      4 - 12.00" / 305 mm guns (2x2 guns), 864.00lbs / 391.90kg shells, 1905 Model
	  Breech loading guns in turrets (on barbettes)
	  on centreline ends, evenly spread, all raised mounts
      9 - 6.00" / 152 mm guns in single mounts, 108.00lbs / 48.99kg shells, 1905 Model
	  Quick firing guns in deck mounts 
	  on side, evenly spread, all raised mounts
	Weight of broadside 4,428 lbs / 2,009 kg
	Shells per gun, main battery: 0

Armour:
   - Belts:		Width (max)	Length (avg)		Height (avg)
	Main:	4.00" / 102 mm	460.00 ft / 140.21 m	20.00 ft / 6.10 m
	Ends:	Unarmoured
	  Main Belt covers 92 % of normal length
	  Main belt does not fully cover magazines and engineering spaces

   - Torpedo Bulkhead:
		1.50" / 38 mm	460.00 ft / 140.21 m	25.00 ft / 7.62 m

   - Gun armour:	Face (max)	Other gunhouse (avg)	Barbette/hoist (max)
	Main:	10.0" / 254 mm	6.00" / 152 mm		8.00" / 203 mm
	2nd:	2.00" / 51 mm	      -			      -

   - Armour deck: 2.00" / 51 mm, Conning tower: 10.00" / 254 mm

Machinery:
	Oil fired boilers, steam turbines, 
	Direct drive, 4 shafts, 142,369 shp / 106,207 Kw = 31.00 kts
	Range 6,000nm at 15.00 kts
	Bunker at max displacement = 5,700 tons

Complement:
	1,147 - 1,492

Cost:
	£2.687 million / $10.749 million

Distribution of weights at normal displacement:
	Armament: 554 tons, 1.8 %
	Armour: 5,256 tons, 17.4 %
	   - Belts: 1,576 tons, 5.2 %
	   - Torpedo bulkhead: 638 tons, 2.1 %
	   - Armament: 1,023 tons, 3.4 %
	   - Armour Deck: 1,809 tons, 6.0 %
	   - Conning Tower: 209 tons, 0.7 %
	Machinery: 9,245 tons, 30.5 %
	Hull, fittings & equipment: 11,463 tons, 37.8 %
	Fuel, ammunition & stores: 3,772 tons, 12.5 %
	Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
	Survivability (Non-critical penetrating hits needed to sink ship):
	  32,682 lbs / 14,824 Kg = 37.8 x 12.0 " / 305 mm shells or 3.3 torpedoes
	Stability (Unstable if below 1.00): 1.21
	Metacentric height 5.6 ft / 1.7 m
	Roll period: 15.1 seconds
	Steadiness	- As gun platform (Average = 50 %): 81 %
			- Recoil effect (Restricted arc if above 1.00): 0.59
	Seaboat quality  (Average = 1.00): 1.62

Hull form characteristics:
	Hull has rise forward of midbreak
	Block coefficient: 0.623
	Length to Beam Ratio: 9.06 : 1
	'Natural speed' for length: 27.75 kts
	Power going to wave formation at top speed: 53 %
	Trim (Max stability = 0, Max steadiness = 100): 50
	Bow angle (Positive = bow angles forward): -1.00 degrees
	Stern overhang: -2.00 ft / -0.61 m
	Freeboard (% = measuring location as a percentage of overall length):
	   - Stem:		35.00 ft / 10.67 m
	   - Forecastle (20 %):	33.00 ft / 10.06 m
	   - Mid (81 %):		32.00 ft / 9.75 m (20.00 ft / 6.10 m aft of break)
	   - Quarterdeck (15 %):	20.00 ft / 6.10 m
	   - Stern:		20.00 ft / 6.10 m
	   - Average freeboard:	30.39 ft / 9.26 m

Ship space, strength and comments:
	Space	- Hull below water (magazines/engines, low = better): 146.4 %
		- Above water (accommodation/working, high = better): 257.7 %
	Waterplane Area: 48,905 Square feet or 4,543 Square metres
	Displacement factor (Displacement / loading): 108 %
	Structure weight / hull surface area: 148 lbs/sq ft or 721 Kg/sq metre
	Hull strength (Relative):
		- Cross-sectional: 0.95
		- Longitudinal: 1.53
		- Overall: 1.00
	Hull space for machinery, storage, compartmentation is cramped
	Room for accommodation and workspaces is excellent
	Ship has slow, easy roll, a good, steady gun platform
	Excellent seaboat, comfortable, can fire her guns in the heaviest weather

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