Plan C-2, planned replacement for the Songrimsŏng-class battleships
Under the terms of the Selkiö Naval Treaty, Menghe was allowed to lay down three battleships in 1935, 1936, and 1937 as replacements for the three Songrimsŏng-class battleships. These battleships would be limited to an individual displacement of 35,000 tonnes, and furthermore would be limited to a main gun caliber of 14", like their predecessors.
Menghean engineers considered a variety of proposals, including a 32kt fast commerce raider, before settling on the final design, which was designated
Byŏng-i (
Byŏng as the third ordinal stem and
i meaning two), often rendered C-2 in Western sources. C-2 was a relatively conservative design, reflecting the conservatism of the Imperial Menghean Navy: with a design speed of 28 knots and a range of 4,000 nautical miles at 14 knots, it was designed to sortie from port and engage in a decisive line battle along Menghe's other battleships. Further reflecting this role, it had a 350mm main armor belt and a 125mm armor deck with a 25mm de-capping plate above, making it one of the more heavily-armored treaty battleship designs. The main armament of twelve 356mm guns was also selected to preserve the Songrimsŏngs' 12-gun broadside, albeit in a 3x4 arrangement rather than their precursors' 4x3. The four-gun turrets would have been built with anti-flash protection walls between the port and starboard gun wells to limit damage from penetrating hits and accidents.
Compromises showed up not just in range and speed, but in the arrangement of the secondary battery, which consisted of eight 130mm L/55 Type 32 high-velocity guns in two four-gun (two-pair) dual-purpose turrets. The superfiring positioning of these turrets allowed reasonable weight savings, as all eight guns could be fired in broadside, and four could cover targets directly forward or astern. The firing arcs of these turrets, however, were mediocre, with each one able to cover a 240-degree arc. Concentration of the secondary guns also meant that if either turret became disabled due to mechanical faults or enemy fire, the ship would lose half her secondary armament and gain a 120-degree secondary blind spot. The Imperial Menghean Navy considered these drawbacks acceptable, especially as it was working under the impression that an enemy fleet would be limited in the number of light surface combatants it could bring along.
The compromises in anti-air protection would have been less acceptable. The quad 130mm dual-purpose turret's slow traverse speed gave it a hard time tracking fast-moving aircraft, especially as the 30s gave way to the 40s, and the Type 32 gun's unitary, brass-case 130mm ammunition was heavy and unwieldy, meaning that crews quickly grew exhausted during sustained engagements. Neither of these flaws was apparent to designers in 1935, when the IMN still anticipated that aircraft would conduct brief engagements in small groups, making a long-ranged, highly accurate flak gun like the Type 32 ideal for countering them. The initial blueprint also called for twelve 37.5mm anti-air guns in six mounts, firing contact-fused, manually-loaded ammunition; if Plan C-2 had been laid down in 1935 as initially planned, these would have almost certainly been replaced by Type 38 37.5mm anti-aircraft autocannons during fitting-out.
Menghe made preparations to lay down the first C-2 battleship in 1935, but on 7 May of that year Menghe declared war on Sylva, beginning the collapse of the Selkiö treaty system. None of the C-2 battleships were ever built, though their design laid the groundwork for Menghe's wartime Chanam-class battleships, which far surpassed the 35,000-ton limit and boasted superior speed and range. Because they were never laid down, they never received names, so this image is simply captioned "Plan C-2 battleship" and does not show a name on the hull side.
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BB Plan C-2, Imperial Menghe Treaty battleship laid down 1935
Displacement:
32,466 t light; 34,989 t standard; 36,131 t normal; 37,045 t full load
Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
(710.58 ft / 693.57 ft) x 108.60 ft x (30.81 / 31.39 ft)
(216.58 m / 211.40 m) x 33.10 m x (9.39 / 9.57 m)
Armament:
12 - 14.02" / 356 mm 50.0 cal guns - 1,457.37lbs / 661.05kg shells, 170 per gun
Breech loading guns in turret on barbette mounts, 1935 Model
3 x 4-gun mounts on centreline ends, majority forward
1 raised mount - superfiring
8 - 5.12" / 130 mm 55.0 cal guns - 72.36lbs / 32.82kg shells, 400 per gun
Dual purpose guns in turret on barbette mounts, 1932 Model
2 x Quad mounts on centreline ends, evenly spread
2 double raised mounts
12 - 1.48" / 37.5 mm 50.0 cal guns - 1.70lbs / 0.77kg shells, 1,500 per gun
Anti-air guns in deck mounts, 1930 Model
5 x Single mounts on sides, evenly spread
4 raised mounts
1 x Single mount on sides, forward deck aft
1 double raised mount
8 - 0.49" / 12.5 mm 60.0 cal guns - 0.07lbs / 0.03kg shells, 10,000 per gun
Machine guns in deck mounts, 1931 Model
6 x Single mounts on sides, evenly spread
2 raised mounts
2 x Single mounts layout not set
2 double raised mounts
Weight of broadside 18,088 lbs / 8,205 kg
Armour:
- Belts: Width (max) Length (avg) Height (avg)
Main: 13.8" / 350 mm 456.04 ft / 139.00 m 12.50 ft / 3.81 m
Ends: Unarmoured
Main Belt covers 101 % of normal length
Main belt does not fully cover magazines and engineering spaces
- Torpedo Bulkhead - Strengthened structural bulkheads:
2.95" / 75 mm 456.04 ft / 139.00 m 28.18 ft / 8.59 m
Beam between torpedo bulkheads 78.74 ft / 24.00 m
- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 15.7" / 400 mm 7.87" / 200 mm 13.8" / 350 mm
2nd: 3.94" / 100 mm 2.95" / 75 mm 1.97" / 50 mm
- Armoured deck - single deck:
For and Aft decks: 5.91" / 150 mm
Forecastle: 0.00" / 0 mm Quarter deck: 2.95" / 75 mm
- Conning towers: Forward 13.78" / 350 mm, Aft 0.00" / 0 mm
Machinery:
Oil fired boilers, steam turbines,
Geared drive, 4 shafts, 94,817 shp / 70,733 Kw = 28.00 kts
Range 4,000nm at 14.00 kts
Bunker at max displacement = 2,056 tons
Complement:
1,309 - 1,703
Cost:
£17.281 million / $69.125 million
Distribution of weights at normal displacement:
Armament: 4,219 tons, 11.7 %
- Guns: 4,219 tons, 11.7 %
Armour: 13,376 tons, 37.0 %
- Belts: 3,421 tons, 9.5 %
- Torpedo bulkhead: 1,404 tons, 3.9 %
- Armament: 3,000 tons, 8.3 %
- Armour Deck: 5,227 tons, 14.5 %
- Conning Tower: 324 tons, 0.9 %
Machinery: 2,694 tons, 7.5 %
Hull, fittings & equipment: 12,177 tons, 33.7 %
Fuel, ammunition & stores: 3,665 tons, 10.1 %
Miscellaneous weights: 0 tons, 0.0 %
Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
48,717 lbs / 22,098 Kg = 35.4 x 14.0 " / 356 mm shells or 8.4 torpedoes
Stability (Unstable if below 1.00): 1.17
Metacentric height 7.5 ft / 2.3 m
Roll period: 16.6 seconds
Steadiness - As gun platform (Average = 50 %): 51 %
- Recoil effect (Restricted arc if above 1.00): 0.53
Seaboat quality (Average = 1.00): 1.00
Hull form characteristics:
Hull has a flush deck,
an extended bulbous bow and large transom stern
Block coefficient (normal/deep): 0.545 / 0.548
Length to Beam Ratio: 6.39 : 1
'Natural speed' for length: 31.05 kts
Power going to wave formation at top speed: 53 %
Trim (Max stability = 0, Max steadiness = 100): 51
Bow angle (Positive = bow angles forward): 25.00 degrees
Stern overhang: 2.62 ft / 0.80 m
Freeboard (% = length of deck as a percentage of waterline length):
Fore end, Aft end
- Forecastle: 17.70 %, 30.84 ft / 9.40 m, 21.65 ft / 6.60 m
- Forward deck: 30.00 %, 21.65 ft / 6.60 m, 18.86 ft / 5.75 m
- Aft deck: 35.90 %, 18.86 ft / 5.75 m, 18.86 ft / 5.75 m
- Quarter deck: 16.40 %, 18.86 ft / 5.75 m, 18.86 ft / 5.75 m
- Average freeboard: 20.43 ft / 6.23 m
Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 101.3 %
- Above water (accommodation/working, high = better): 154.5 %
Waterplane Area: 54,462 Square feet or 5,060 Square metres
Displacement factor (Displacement / loading): 99 %
Structure weight / hull surface area: 218 lbs/sq ft or 1,063 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.96
- Longitudinal: 1.44
- Overall: 1.00
Adequate machinery, storage, compartmentation space
Excellent accommodation and workspace room
