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Friday, January 28, 2005

Another run at a Japanese Heavy Cruiser: Jap/CA/1921b1

I have another, rather unsatisfactory, Japanese heavy cruiser design: Jap/CA/1927b1. I like the 9.4in gun and wanted at least a 35 knot speed. What I got was another ship that was too large (I'm working in an environment where I have blown off the Washington Naval Treat limitations):
Jap/CA/9127b1, Japan Heavy Cruiser laid down 1927

Displacement:
	17,158 t light; 17,937 t standard; 19,511 t normal; 20,770 t full load

Dimensions: Length overall / water x beam x draught
	724.08 ft / 721.00 ft x 71.00 ft x 29.00 ft (normal load)
	220.70 m / 219.76 m x 21.64 m  x 8.84 m

Armament:
      9 - 9.40" / 239 mm guns (3 mounts), 415.29lbs / 188.37kg shells, 1927 Model
	  Breech loading guns in turrets (on barbettes)
	  on centreline ends, majority forward, 8 raised guns - superfiring
      12 - 5.00" / 127 mm guns (6x2 guns), 62.50lbs / 28.35kg shells, 1927 Model
	  Dual purpose guns in deck mounts with hoists
	  on side, all amidships, all raised mounts - superfiring
      33 - 0.98" / 25.0 mm guns (11x3 guns), 0.48lbs / 0.22kg shells, 1927 Model
	  Anti-aircraft guns in deck mounts 
	  on side ends, majority forward, all raised mounts - superfiring
	Weight of broadside 4,503 lbs / 2,043 kg
	Shells per gun, main battery: 150
	12 - 24.0" / 609.6 mm above water torpedoes

Armour:
   - Belts:		Width (max)	Length (avg)		Height (avg)
	Main:	3.00" / 76 mm	520.00 ft / 158.50 m	12.00 ft / 3.66 m
	Ends:	Unarmoured
	  Main Belt covers 111 % of normal length
	  Main belt does not fully cover magazines and engineering spaces

   - Torpedo Bulkhead:
		1.00" / 25 mm	520.00 ft / 158.50 m	24.00 ft / 7.32 m

   - Gun armour:	Face (max)	Other gunhouse (avg)	Barbette/hoist (max)
	Main:	5.00" / 127 mm	3.00" / 76 mm		3.00" / 76 mm
	2nd:	1.00" / 25 mm	      -			      -

   - Armour deck: 3.00" / 76 mm, Conning tower: 4.00" / 102 mm

Machinery:
	Oil fired boilers, steam turbines, 
	Geared drive, 4 shafts, 165,668 shp / 123,588 Kw = 35.00 kts
	Range 9,000nm at 14.00 kts
	Bunker at max displacement = 2,833 tons

Complement:
	825 - 1,073

Cost:
	£6.565 million / $26.262 million

Distribution of weights at normal displacement:
	Armament: 563 tons, 2.9 %
	Armour: 3,619 tons, 18.5 %
	   - Belts: 765 tons, 3.9 %
	   - Torpedo bulkhead: 462 tons, 2.4 %
	   - Armament: 503 tons, 2.6 %
	   - Armour Deck: 1,827 tons, 9.4 %
	   - Conning Tower: 62 tons, 0.3 %
	Machinery: 5,229 tons, 26.8 %
	Hull, fittings & equipment: 7,747 tons, 39.7 %
	Fuel, ammunition & stores: 2,353 tons, 12.1 %
	Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
	Survivability (Non-critical penetrating hits needed to sink ship):
	  17,302 lbs / 7,848 Kg = 41.7 x 9.4 " / 239 mm shells or 2.2 torpedoes
	Stability (Unstable if below 1.00): 1.12
	Metacentric height 3.7 ft / 1.1 m
	Roll period: 15.5 seconds
	Steadiness	- As gun platform (Average = 50 %): 54 %
			- Recoil effect (Restricted arc if above 1.00): 0.72
	Seaboat quality  (Average = 1.00): 1.02

Hull form characteristics:
	Hull has a flush deck
	Block coefficient: 0.460
	Length to Beam Ratio: 10.15 : 1
	'Natural speed' for length: 26.85 kts
	Power going to wave formation at top speed: 55 %
	Trim (Max stability = 0, Max steadiness = 100): 53
	Bow angle (Positive = bow angles forward): 2.00 degrees
	Stern overhang: 2.00 ft / 0.61 m
	Freeboard (% = measuring location as a percentage of overall length):
	   - Stem:		31.00 ft / 9.45 m
	   - Forecastle (20 %):	21.00 ft / 6.40 m
	   - Mid (50 %):		21.00 ft / 6.40 m
	   - Quarterdeck (15 %):	21.00 ft / 6.40 m
	   - Stern:		21.00 ft / 6.40 m
	   - Average freeboard:	21.80 ft / 6.64 m

Ship space, strength and comments:
	Space	- Hull below water (magazines/engines, low = better): 152.3 %
		- Above water (accommodation/working, high = better): 126.0 %
	Waterplane Area: 32,926 Square feet or 3,059 Square metres
	Displacement factor (Displacement / loading): 105 %
	Structure weight / hull surface area: 141 lbs/sq ft or 686 Kg/sq metre
	Hull strength (Relative):
		- Cross-sectional: 0.96
		- Longitudinal: 1.33
		- Overall: 1.00
	Hull space for machinery, storage, compartmentation is cramped
	Room for accommodation and workspaces is excellent

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