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Thursday, January 06, 2005

My design study for a British "1921" battlecruiser

I guess I should be happy that my British 1921 battlecruiser design study turned out as well as it did. The idea was to have a 48,000 ton ships with a speed of 30 knots, with 9-16in guns, a 14in belt and turrets, and strong deck armor. I was able to go to a 5in deck, so that was good. I had to grow the ship to do everything I wanted, but it wasn't excessive, unlike some times. Springsharp complains that the ship is not good enough for its size.
GB/CB/1921a1, Great Britain Battlecruiser laid down 1921

Displacement:
	46,469 t light; 48,612 t standard; 51,761 t normal; 54,281 t full load

Dimensions: Length overall / water x beam x draught
	856.12 ft / 855.00 ft x 105.00 ft x 33.30 ft (normal load)
	260.94 m / 260.60 m x 32.00 m  x 10.15 m

Armament:
     9 - 16.00" / 406 mm guns (3x3 guns), 2,048.00lbs / 928.96kg shells, 1921 Model
	  Breech loading guns in turrets (on barbettes)
	  on centreline ends, majority forward, all raised mounts - superfiring
	  Main guns limited to end-on fire
     20 - 5.00" / 127 mm guns (10x2 guns), 62.50lbs / 28.35kg shells, 1921 Model
	  Quick firing guns in turrets (on barbettes)
	  on side, evenly spread, all raised mounts
	Weight of broadside 19,682 lbs / 8,928 kg
	Shells per gun, main battery: 100

Armour:
  - Belts:		Width (max)	Length (avg)		Height (avg)
	Main:	14.0" / 356 mm	440.00 ft / 134.11 m	16.00 ft / 4.88 m
	Ends:	Unarmoured
	  Main Belt covers 79 % of normal length

  - Gun armour:	Face (max)	Other gunhouse (avg)	Barbette/hoist (max)
	Main:	14.0" / 356 mm	9.00" / 229 mm		14.0" / 356 mm
	2nd:	3.00" / 76 mm	2.00" / 51 mm		2.00" / 51 mm

  - Armour deck: 5.00" / 127 mm

Machinery:
	Oil fired boilers, steam turbines,
	Geared drive, 4 shafts, 168,135 shp / 125,429 Kw = 30.00 kts
	Range 8,000nm at 15.00 kts
	Bunker at max displacement = 5,669 tons

Complement:
	1,715 - 2,230

Cost:
	£11.464 million / $45.855 million

Distribution of weights at normal displacement:
	Armament: 2,460 tons, 4.8 %
	Armour: 15,663 tons, 30.3 %
	   - Belts: 4,398 tons, 8.5 %
	   - Torpedo bulkhead: 0 tons, 0.0 %
	   - Armament: 5,157 tons, 10.0 %
	   - Armour Deck: 6,108 tons, 11.8 %
	   - Conning Tower: 0 tons, 0.0 %
	Machinery: 5,790 tons, 11.2 %
	Hull, fittings & equipment: 22,556 tons, 43.6 %
	Fuel, ammunition & stores: 5,292 tons, 10.2 %
	Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
	Survivability (Non-critical penetrating hits needed to sink ship):
	  64,960 lbs / 29,465 Kg = 31.7 x 16.0 " / 406 mm shells or 4.1 torpedoes
	Stability (Unstable if below 1.00): 0.97
	Metacentric height 5.0 ft / 1.5 m
	Roll period: 19.7 seconds
	Steadiness	- As gun platform (Average = 50 %): 67 %
			- Recoil effect (Restricted arc if above 1.00): 1.31
	Seaboat quality  (Average = 1.00): 1.39

Hull form characteristics:
	Hull has a flush deck
	Block coefficient: 0.606
	Length to Beam Ratio: 8.14 : 1
	'Natural speed' for length: 29.24 kts
	Power going to wave formation at top speed: 50 %
	Trim (Max stability = 0, Max steadiness = 100): 48
	Bow angle (Positive = bow angles forward): 2.00 degrees
	Stern overhang: -1.00 ft / -0.30 m
	Freeboard (% = measuring location as a percentage of overall length):
	   - Stem:		32.00 ft / 9.75 m
	   - Forecastle (20 %):	30.00 ft / 9.14 m
	   - Mid (0 %):		30.00 ft / 9.14 m
	   - Quarterdeck (15 %):	30.00 ft / 9.14 m
	   - Stern:		30.00 ft / 9.14 m
	   - Average freeboard:	30.16 ft / 9.19 m
	Ship tends to be wet forward

Ship space, strength and comments:
	Space	- Hull below water (magazines/engines, low = better): 72.5 %
		- Above water (accommodation/working, high = better): 220.0 %
	Waterplane Area: 66,029 Square feet or 6,134 Square metres
	Displacement factor (Displacement / loading): 110 %
	Structure weight / hull surface area: 229 lbs/sq ft or 1,119 Kg/sq metre
	Hull strength (Relative):
		- Cross-sectional: 0.96
		- Longitudinal: 1.52
		- Overall: 1.01
	Caution: Poor stability - excessive risk of capsizing
	Hull space for machinery, storage, compartmentation is excellent
	Room for accommodation and workspaces is excellent
	Good seaboat, rides out heavy weather easily

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