HIJMS Izumo (Yamato Prototype 1924)

HIJMS Izumo, Japanese Izumo-class battleship laid down 1924 (Engine 1926)

Displacement:
	39,703 t light; 41,773 t standard; 44,120 t normal; 45,998 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
	(742.12 ft / 721.78 ft) x 108.27 ft x (31.17 / 32.28 ft)
	(226.20 m / 220.00 m) x 33.00 m  x (9.50 / 9.84 m)

Armament:
      9 - 16.14" / 410 mm 45.0 cal guns - 2,120.84lbs / 962.00kg shells, 90 per gun
	  Breech loading guns in turret on barbette mounts, 1924 Model
	  2 x 3-gun mounts on centreline, forward deck forward
		1 raised mount - superfiring
	  1 x 3-gun mount on centreline, aft deck aft
      12 - 6.00" / 152 mm 50.0 cal guns - 114.11lbs / 51.76kg shells, 165 per gun
	  Breech loading guns in casemate mounts, 1924 Model
	  12 x Single mounts on sides, evenly spread
      8 - 5.00" / 127 mm 40.0 cal guns - 59.90lbs / 27.17kg shells, 300 per gun
	  Dual purpose guns in deck and hoist mounts, 1924 Model
	  4 x Twin mounts on sides, evenly spread
      12 - 1.57" / 40.0 mm 62.0 cal guns - 2.15lbs / 0.98kg shells, 1,800 per gun
	  Anti-air guns in deck mounts, 1924 Model
	  6 x Twin mounts on sides, evenly spread
      24 - 0.50" / 12.7 mm 62.0 cal guns - 0.07lbs / 0.03kg shells, 2,500 per gun
	  Anti-air guns in deck mounts, 1924 Model
	  4 x 2 row quad mounts on sides, evenly spread
	  2 x 2 row quad mounts on centreline, evenly spread
      Weight of broadside 20,963 lbs / 9,509 kg

Armour:
   - Belts:		Width (max)	Length (avg)		Height (avg)
	Main:	11.8" / 300 mm	375.33 ft / 114.40 m	12.50 ft / 3.81 m
	Ends:	3.15" / 80 mm	346.42 ft / 105.59 m	12.50 ft / 3.81 m
	Upper:	7.87" / 200 mm	375.33 ft / 114.40 m	8.01 ft / 2.44 m
	  Main Belt covers 80 % of normal length

   - Torpedo Bulkhead - Additional damage containing bulkheads:
		5.51" / 140 mm	375.33 ft / 114.40 m	29.79 ft / 9.08 m
	Beam between torpedo bulkheads 101.71 ft / 31.00 m

   - Gun armour:	Face (max)	Other gunhouse (avg)	Barbette/hoist (max)
	Main:	15.7" / 400 mm	7.87" / 200 mm		15.7" / 400 mm
	2nd:	7.87" / 200 mm	5.91" / 150 mm		4.72" / 120 mm
	3rd:	5.51" / 140 mm	3.15" / 80 mm		5.51" / 140 mm

   - Armoured deck - multiple decks:
	For and Aft decks: 3.94" / 100 mm
	Forecastle: 0.98" / 25 mm  Quarter deck: 0.98" / 25 mm

   - Conning towers: Forward 9.06" / 230 mm, Aft 6.30" / 160 mm

Machinery:
	Oil fired boilers, steam turbines,
	Geared drive, 4 shafts, 150,020 shp / 111,915 Kw = 29.11 kts
	Range 7,998nm at 14.00 kts
	Bunker at max displacement = 4,225 tons

Complement:
	1,521 - 1,978

Cost:
	£12.228 million / $48.913 million

Distribution of weights at normal displacement:
	Armament: 4,094 tons, 9.3 %
	   - Guns: 4,094 tons, 9.3 %
	Armour: 14,678 tons, 33.3 %
	   - Belts: 4,133 tons, 9.4 %
	   - Torpedo bulkhead: 2,280 tons, 5.2 %
	   - Armament: 4,474 tons, 10.1 %
	   - Armour Deck: 3,378 tons, 7.7 %
	   - Conning Towers: 413 tons, 0.9 %
	Machinery: 4,802 tons, 10.9 %
	Hull, fittings & equipment: 16,129 tons, 36.6 %
	Fuel, ammunition & stores: 4,417 tons, 10.0 %
	Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
	Survivability (Non-critical penetrating hits needed to sink ship):
	  61,039 lbs / 27,687 Kg = 29.0 x 16.1 " / 410 mm shells or 10.2 torpedoes
	Stability (Unstable if below 1.00): 1.06
	Metacentric height 6.3 ft / 1.9 m
	Roll period: 18.1 seconds
	Steadiness	- As gun platform (Average = 50 %): 70 %
			- Recoil effect (Restricted arc if above 1.00): 0.90
	Seaboat quality  (Average = 1.00): 1.14

Hull form characteristics:
	Hull has a flush deck,
	  a straight bulbous bow and a cruiser stern
	Block coefficient (normal/deep): 0.634 / 0.638
	Length to Beam Ratio: 6.67 : 1
	'Natural speed' for length: 26.87 kts
	Power going to wave formation at top speed: 56 %
	Trim (Max stability = 0, Max steadiness = 100): 61
	Bow angle (Positive = bow angles forward): 25.00 degrees
	Stern overhang: 6.56 ft / 2.00 m
	Freeboard (% = length of deck as a percentage of waterline length):
				Fore end,	 Aft end
	   - Forecastle:	24.00 %,  29.53 ft / 9.00 m,  26.25 ft / 8.00 m
	   - Forward deck:	26.00 %,  26.25 ft / 8.00 m,  26.25 ft / 8.00 m
	   - Aft deck:	26.00 %,  26.25 ft / 8.00 m,  26.25 ft / 8.00 m
	   - Quarter deck:	24.00 %,  26.25 ft / 8.00 m,  26.25 ft / 8.00 m
	   - Average freeboard:		26.56 ft / 8.10 m
	Ship tends to be wet forward

Ship space, strength and comments:
	Space	- Hull below water (magazines/engines, low = better): 79.3 %
		- Above water (accommodation/working, high = better): 193.9 %
	Waterplane Area: 58,989 Square feet or 5,480 Square metres
	Displacement factor (Displacement / loading): 104 %
	Structure weight / hull surface area: 217 lbs/sq ft or 1,061 Kg/sq metre
	Hull strength (Relative):
		- Cross-sectional: 0.94
		- Longitudinal: 1.78
		- Overall: 1.00
	Excellent machinery, storage, compartmentation space
	Excellent accommodation and workspace room
	Ship has slow, easy roll, a good, steady gun platform

Lead ship of the Izumo-class battleships. Converted in 1938 to a fleet carrier. Machinery and turrets served as prototypes for the Yamato-class battleships. Alternative to the Number 13-class battleships, to better comply with Washington Naval Treaty restrictions.