Shipbucket

Heuksu-Class Main Force Cruiser


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Displacement: 24,980 tons standard / 30,670 tons full load
Length: 240.8 m
Beam: 28.0 m
Draught: 8.00 m
Propulsion: 110,000 shp on four shafts
Speed: 31.5 kt
Range: 7,500 nmi at 14 knots
Complement: 1,350
Armament:
- 3 x 25 cm/50 naval guns (3x3)
- 12 x 12.5 cm/45 dual purpose guns (6x2)
- 16 × 4 cm/70 AA guns (4x4)
Armor:
- Belt: 330 mm
- Barbettes: 350 mm
- Turret: 325 mm
- Deck: 160 mm
- Conning Tower: 250 mm
Aircraft carried: 2


During the early 1930s, Britain set about pushing for a limit of 25,000 tons and 12" main armament for capital ships. While Korea thought this absurd in the face of a belligerent China, it did humor its close ally by supporting the notion and designing its own 25,000 capital ship. The result was the Heuksu.

Named for the longest river of the Empire (internationally known as Amur), Heuksu attempted to push the possibilities of 25,00 tons displacement to the limit. The goal was immunity from 14" shells between 19,000 and 30,000 yards while also achieving a maximum speed of over 30 knots. If this meant that the main armament needed to be made smaller, that was a sacrifice Korea was willing to make. It did have a large stockpile of tungsten from its mines, so if there need be it would be manufacturing heavy AP rounds to boost the smaller caliber. Ultimately the result barely made it.

The Chinese denunciation of naval treaties in 1934 after demanding naval parity virtually destroyed Britain's ambitions. With the second most powerful industrial power unchained, reducing tonnage limits was not going to be accepted by either Korea or Japan. Along with the 25,000 ton plan, Heuksu was almost thrown away as it was considered just an exercise in designing. It seemed that Heuksu would be a still born.

However, the eruption of the Sino-Korean War in 1936 revived the design. With the Chinese armada blockading all of Northeast Asia, a fast sturdy vessel was needed to crack through the Bamboo Curtain. Heuksu and her sisters were ordered immediately, and when they entered action in 1938, they managed to punch through parts of the blockage force. The birth of the "Main Force Cruiser" started a revolution, as the death of naval restrictions led to escalating growth of cruisers into the realm of capital ships.


Commentary: This world's "large cruiser" are named "main force cruiser", and you can see the semi-consolidated superstructure design here would lead to the formation of the heavily armored Korean "Panok" design, as shown with the battleship Gwangmu.

Reran SpringSharp for Gwangmu:

Gwangmu, KJH Battleship laid down 1938

Displacement:
43,576 t light; 45,720 t standard; 48,383 t normal; 50,513 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
(793.22 ft / 772.64 ft) x 118.11 ft x (33.14 / 34.30 ft)
(241.77 m / 235.50 m) x 36.00 m x (10.10 / 10.45 m)

Armament:
8 - 15.75" / 400 mm 45.0 cal guns - 1,969.41lbs / 893.31kg shells, 100 per gun
Breech loading guns in turret on barbette mounts, 1938 Model
4 x 2-gun mounts on centreline ends, evenly spread
2 raised mounts - superfiring
20 - 4.92" / 125 mm 45.0 cal guns - 60.10lbs / 27.26kg shells, 450 per gun
Dual purpose guns in turret on barbette mounts, 1938 Model
6 x Twin mounts on side ends, majority forward
4 x Twin mounts on sides aft
4 raised mounts
Weight of broadside 16,957 lbs / 7,692 kg

Armour:
- Belts: Width (max) Length (avg) Height (avg)
Main: 14.8" / 375 mm 426.51 ft / 130.00 m 13.48 ft / 4.11 m
Ends: 5.91" / 150 mm 262.47 ft / 80.00 m 6.99 ft / 2.13 m
83.66 ft / 25.50 m Unarmoured ends
Main Belt covers 85 % of normal length

- Torpedo Bulkhead:
7.09" / 180 mm 426.51 ft / 130.00 m 30.61 ft / 9.33 m

- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 20.1" / 510 mm 9.84" / 250 mm 20.9" / 530 mm
2nd: 0.75" / 19 mm 0.75" / 19 mm 1.77" / 45 mm

- Armoured deck - multiple decks: 5.12" / 130 mm For and Aft decks

- Conning towers: Forward 20.87" / 530 mm, Aft 0.00" / 0 mm

Machinery:
Oil fired boilers, steam turbines,
Geared drive, 4 shafts, 125,216 shp / 93,411 Kw = 27.80 kts
Range 7,200nm at 16.00 kts
Bunker at max displacement = 4,793 tons

Complement:
1,630 - 2,120

Cost:
£20.225 million / $80.900 million

Distribution of weights at normal displacement:
Armament: 3,431 tons, 7.1 %
Armour: 18,030 tons, 37.3 %
- Belts: 4,218 tons, 8.7 %
- Torpedo bulkhead: 3,423 tons, 7.1 %
- Armament: 5,313 tons, 11.0 %
- Armour Deck: 4,479 tons, 9.3 %
- Conning Tower: 597 tons, 1.2 %
Machinery: 3,429 tons, 7.1 %
Hull, fittings & equipment: 18,587 tons, 38.4 %
Fuel, ammunition & stores: 4,806 tons, 9.9 %
Miscellaneous weights: 100 tons, 0.2 %
- On freeboard deck: 100 tons

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
88,538 lbs / 40,160 Kg = 45.3 x 15.7 " / 400 mm shells or 20.9 torpedoes
Stability (Unstable if below 1.00): 1.14
Metacentric height 8.2 ft / 2.5 m
Roll period: 17.3 seconds
Steadiness - As gun platform (Average = 50 %): 62 %
- Recoil effect (Restricted arc if above 1.00): 0.46
Seaboat quality (Average = 1.00): 1.22

Hull form characteristics:
Hull has a flush deck,
a normal bow and a round stern
Block coefficient (normal/deep): 0.560 / 0.565
Length to Beam Ratio: 6.54 : 1
'Natural speed' for length: 27.80 kts
Power going to wave formation at top speed: 50 %
Trim (Max stability = 0, Max steadiness = 100): 51
Bow angle (Positive = bow angles forward): 30.00 degrees
Stern overhang: 1.64 ft / 0.50 m
Freeboard (% = length of deck as a percentage of waterline length):
Fore end, Aft end
- Forecastle: 23.00 %, 32.81 ft / 10.00 m, 22.31 ft / 6.80 m
- Forward deck: 30.00 %, 22.31 ft / 6.80 m, 22.31 ft / 6.80 m
- Aft deck: 25.00 %, 22.31 ft / 6.80 m, 22.31 ft / 6.80 m
- Quarter deck: 22.00 %, 22.31 ft / 6.80 m, 26.25 ft / 8.00 m
- Average freeboard: 23.71 ft / 7.23 m

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 64.8 %
- Above water (accommodation/working, high = better): 167.6 %
Waterplane Area: 64,287 Square feet or 5,972 Square metres
Displacement factor (Displacement / loading): 121 %
Structure weight / hull surface area: 231 lbs/sq ft or 1,126 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 1.05
- Longitudinal: 1.48
- Overall: 1.08
Hull space for machinery, storage, compartmentation is excellent
Room for accommodation and workspaces is excellent
Good seaboat, rides out heavy weather easily

Had to install only 8 guns for this draft since SpringSharp was overestimating armament weight by about 1,000 tons when I put 10 guns.

Anything you notice that might need to be changed?

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Finally got down to taking out the 40 mm Mark VI and electronics. Does anyone have any suggestions on 1942~1943 radar and electronics I might use?

why is the superstructure so big.

It's actually pretty small:



Iowa, Gwangmu, Massachusetts

It doesn't have the fire control tower, and the general bridge is shorter than even Massachusetts. Everything is packed tightly together, although the longer bow means more potential living space for the crew.

vessel has no anti aircraft guns or radar

Why did I write the following:
Anyway, almost finalizing the radar. Let's see how I can go about this.....

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AA directors and aerial radars remain to be installed. Not sure what to do with the rear mast, likely to take it out and replace it with something similar to the attached mast of South Dakota.

Battleship Gwangmu, as finished in 1940


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Displacement: 45,720 tons standard / 56,820 tons full load
Length: 243.1 m
Beam: 36.0 m
Draught: 10.1 m
Propulsion: 130,000 shp on four shafts
Speed: 27.8 kt
Range: 7,200 nmi at 16 knots
Complement: 2,120
Armament:
- 10 x 40 cm/45 naval guns (2x3, 2x2)
- 20 x 12.5 cm/45 dual purpose guns (10x2)
- 64 × 4 cm/56 AA guns (14x4)
Armor:
- Belt: 400 mm
- Barbettes: 530 mm
- Turret: 510 mm
- Deck: 150 mm
- Conning Tower: 530 mm
Aircraft carried: 2

Battleship designed after the start of the Sino-Korean War in 1936. It was the first battleship to be finished under the escalator clause allowing displacement of 45,000 tons. Armored heavily to protect against possible 18" rounds, it went in the opposite direction of the American design philosophy of speed over armor, since its mission was to ensure naval superiority in the surrounding waters of the Greater Korean Empire.


I believe I'm finished with this one. If you notice anything strange, please tell me.

Personally (but it will spoil you nice drawing) I would go with 3x3 main guns,

- Will make you only need to design and build 1 type of turret. (one of the main delays with making BBs and you are going for an early date)
- Will free up length and weight to add to the belt If you want to fight 18' ships. (You 400mm belt only works v IJN 18' beyond 29k yards IMO with an IZ 29-31 ish using RN quality steel)
- I still think its more a 1940 design rather than 1936 and commissioned 1940 (Size,AA guns,radars) but its your AU so handwave that away.

My only other question is if China is sorted sufficiently to build 18' monsters then I think you will be losing the land war badly and this ship will not matter much ?

JSB