Shipbucket

As I said to BB1987, a cruiser was in the works! And now, here she is!

The IJN's designers were quite pleased with their Myoko- and Takao-class CAs; the ships, with their ten 8-inch guns, were the most heavily-armed heavy cruisers in the world. But for some, it wasn't enough. Some officers wanted a ship that no cruiser could contest. Not a battleship, but not a battlecruiser either. As such, the 'Large Cruiser' concept was introduced. As the Myokos were nearing completion at the end of the 1920s, the Ordnance branch designed and successfully tested a 10-inch gun, which was immediately approved for the new ships. Turrets were designed through the early 1930s, and both a twin and triple-mount design were approved, both of which were used in the initial large cruiser class, with twin mounts superfiring over triples, giving ten 10-inch guns in total. The hull design proved so successful, it was used for not only three classes of large cruisers, but also three classes of battlecruiser.

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MS State Guard - 08 March 2014 - 28 January 2023

The Official IJN Ships & Planes List

#FJB

Seems like a truly immense hull for that armament. And you've got some mismatches in shades of red below the waterline amidships, on the rudder, and near the shafts. Certainly attractive, though.

Fixed the underwater hull shading.

-Matt

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MS State Guard - 08 March 2014 - 28 January 2023

The Official IJN Ships & Planes List

#FJB

I'd like to see a Springsharp of that baby!

if Emperor does not mind i'll provide it.

Iwate, Japan Large Cruiser laid down 1931

Displacement:
26.436 t light; 27.608 t standard; 32.227 t normal; 35.923 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
(808,08 ft / 787,40 ft) x 89,24 ft x (28,87 / 31,49 ft)
(246,30 m / 240,00 m) x 27,20 m x (8,80 / 9,60 m)

Armament:
10 - 10,00" / 254 mm 45,0 cal guns - 504,26lbs / 228,73kg shells, 150 per gun
Breech loading guns in turret on barbette mounts, 1931 Model
2 x Triple mounts on centreline ends, evenly spread
2 x Twin mounts on centreline ends, evenly spread
2 raised mounts
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, 1932 Model
4 x Twin mounts on sides, evenly spread
4 raised mounts
10 - 0,98" / 25,0 mm 70,0 cal guns - 0,53lbs / 0,24kg shells, 9.000 per gun
Machine guns in deck mounts, 1935 Model
6 x Single mounts on sides, evenly spread
2 x Twin mounts on sides, forward deck aft
2 double raised mounts
4 - 0,51" / 13,0 mm 45,0 cal guns - 0,07lbs / 0,03kg shells, 9.000 per gun
Machine guns in deck mounts, 1933 Model
2 x Twin mounts on sides, forward deck centre
2 double raised mounts
Weight of broadside 5.527 lbs / 2.507 kg
Main Torpedoes
8 - 24,9" / 633 mm, 32,81 ft / 10,00 m torpedoes - 2,897 t each, 23,174 t total
In 2 sets of deck mounted side rotating tubes

Armour:
- Belts: Width (max) Length (avg) Height (avg)
Main: 8,19" / 208 mm 456,69 ft / 139,20 m 11,35 ft / 3,46 m
Ends: Unarmoured
Upper: 4,02" / 102 mm 456,69 ft / 139,20 m 8,01 ft / 2,44 m
Main Belt covers 89% of normal length

- Torpedo Bulkhead - Additional damage containing bulkheads:
2,99" / 76 mm 456,69 ft / 139,20 m 26,61 ft / 8,11 m
Beam between torpedo bulkheads 82,68 ft / 25,20 m

- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 7,99" / 203 mm 2,99" / 76 mm 4,02" / 102 mm
2nd: 0,98" / 25 mm 0,63" / 16 mm 0,98" / 25 mm

- Armoured deck - multiple decks:
For and Aft decks: 4,92" / 125 mm
Forecastle: 0,00" / 0 mm Quarter deck: 0,98" / 25 mm

- Conning towers: Forward 10,00" / 254 mm, Aft 0,00" / 0 mm

Machinery:
Oil fired boilers, steam turbines,
Geared drive, 4 shafts, 206.479 shp / 154.033 Kw = 34,00 kts
Range 12.000nm at 18,00 kts
Bunker at max displacement = 8.314 tons

Complement:
1.202 - 1.563

Cost:
£10,048 million / $40,191 million

Distribution of weights at normal displacement:
Armament: 1.266 tons, 3,9%
- Guns: 1.219 tons, 3,8%
- Weapons: 46 tons, 0,1%
Armour: 8.233 tons, 25,5%
- Belts: 2.433 tons, 7,5%
- Torpedo bulkhead: 1.345 tons, 4,2%
- Armament: 691 tons, 2,1%
- Armour Deck: 3.546 tons, 11,0%
- Conning Tower: 218 tons, 0,7%
Machinery: 6.175 tons, 19,2%
Hull, fittings & equipment: 9.762 tons, 30,3%
Fuel, ammunition & stores: 5.792 tons, 18,0%
Miscellaneous weights: 1.000 tons, 3,1%
- On freeboard deck: 500 tons
- Above deck: 500 tons

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
44.137 lbs / 20.020 Kg = 88,3 x 10,0 " / 254 mm shells or 2,9 torpedoes
Stability (Unstable if below 1.00): 1,27
Metacentric height 6,5 ft / 2,0 m
Roll period: 14,7 seconds
Steadiness - As gun platform (Average = 50 %): 50 %
- Recoil effect (Restricted arc if above 1.00): 0,29
Seaboat quality (Average = 1.00): 0,97

Hull form characteristics:
Hull has a flush deck,
an extended bulbous bow and a cruiser stern
Block coefficient (normal/deep): 0,556 / 0,568
Length to Beam Ratio: 8,82 : 1
'Natural speed' for length: 28,06 kts
Power going to wave formation at top speed: 56 %
Trim (Max stability = 0, Max steadiness = 100): 52
Bow angle (Positive = bow angles forward): 35,00 degrees
Stern overhang: 0,00 ft / 0,00 m
Freeboard (% = length of deck as a percentage of waterline length):
Fore end, Aft end
- Forecastle: 20,90%, 29,53 ft / 9,00 m, 20,67 ft / 6,30 m
- Forward deck: 30,00%, 20,67 ft / 6,30 m, 20,67 ft / 6,30 m
- Aft deck: 28,00%, 20,67 ft / 6,30 m, 20,67 ft / 6,30 m
- Quarter deck: 21,10%, 20,67 ft / 6,30 m, 16,73 ft / 5,10 m
- Average freeboard: 20,99 ft / 6,40 m
Ship tends to be wet forward

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 84,1%
- Above water (accommodation/working, high = better): 158,0%
Waterplane Area: 49.315 Square feet or 4.582 Square metres
Displacement factor (Displacement / loading): 122%
Structure weight / hull surface area: 145 lbs/sq ft or 708 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0,99
- Longitudinal: 1,01
- Overall: 1,00
Adequate machinery, storage, compartmentation space
Excellent accommodation and workspace room
Poor seaboat, wet and uncomfortable, reduced performance in heavy weather


Based everything as a mix between the B65 and the Myokos, the result was an extremely undergunned ship, so i increased the armour and gave her an impressive range of 12.000 miles at 18 knots; still, not a great seaboat at top speed.

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My Worklist
Sources and documentations are the most welcome.

-Koko Kyouwakoku (Republic of Koko)
-Koko's carrier-based aircrafts of WWII
-Koko Kaiun Yuso Kaisha - KoKaYu Line (Koko AU spinoff)
-Koko - Civil Aviation

Envious of my Thevai-class, Matt? I still think my 'boats' can take yours one. with the exception of the oddly shaped stem, it does look cool. I'd rather have preferred the classic, emblematic, prow design of the 'A'-class cruisers.

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My Avatar:Петр Алексеевич Безобразов (Petr Alekseevich Bezobrazov), Вице-адмирал , царская ВМФ России(1845-1906) - I sign my drawings as Ari Saarinen

Thanks, BB! And no, Bezo, not envious...I'm just an IJN nut who loves designing interesting ships. And I'm not too concerned about the loss of speed in heavy weather; these were not designed to run with the carrier forces, but instead serve as smaller consorts to the battlecruisers on the surface units...truly night fighters from hell.

Edited the original drawing to show it's an 'as completed' version. In the meantime, here's the 1944 version:

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MS State Guard - 08 March 2014 - 28 January 2023

The Official IJN Ships & Planes List

#FJB

I would probably prefer the Thevai, even though I like this as well. A cruiser killer should never be that much bigger than the cruiser it's intended to sink. It's not very economic. Then again, the "1946"-threads aren't made with a very economic set of mind.

Beautiful ship Matt, but on the 1944 version the Type 13 air search radar is placed badly, it is too low on the fore mast and has a very large blind spot forward. IMHO it would be better off on the aft mast higher up.

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Thank you Kim for the crest

"Never fear to try on something new. Remember that the Titanic was built by professionals, and the Ark by an amateur"

Fixed the Type 13.

-Matt

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MS State Guard - 08 March 2014 - 28 January 2023

The Official IJN Ships & Planes List

#FJB