The Socialist Republic of Sieran

With a 76' beam you shouldn't need bulges. I've got 4' torpedo bulkheads built into the Rio Grande Class, which has a TE drive. I you provided an armored bulkhead with your TDS, you should be fine.

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Redhorse

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I think there already is an armored torpedo bulkhead. However after removing the bulge and setting the torpedo bulkhead to 100mm and even 120mm, there was no change in survivability against torpedoes. Even reducing the beam between bulkheads did not change anything.

EDIT: Realised I forgot to set a torpedo bulkhead height. Setting it to 4m and a thickness of 50mm increases torpedo survivability to 3.2 x 20" torpedoes, up from 2.4. Doubling the bulkhead gains only .2 and isn't worth the increased weight. Had to thin the conning tower armour and reduce the range to 6000nm to compensate however to get composite strength back up to 1. Not too happy with the reduction of range but survivability improved a bit and I suppose as Sieran primarily operates just in the Bering Sea/Aleutian Islands area, the range isn't a huge issue.

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C3, Socialist Republic of Sieran Cruiser Killer laid down 1935

Displacement:
	15,939 t light; 16,780 t standard; 17,854 t normal; 18,714 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
	(660.39 ft / 649.61 ft) x 76.77 ft x (28.87 / 29.83 ft)
	(201.29 m / 198.00 m) x 23.40 m  x (8.80 / 9.09 m)

Armament:
      9 - 9.45" / 240 mm 50.0 cal guns - 446.52lbs / 202.54kg shells, 100 per gun
	  Breech loading guns in turret on barbette mounts, 1935 Model
	  3 x Single mounts on centreline ends, majority forward
		1 raised mount - superfiring
      16 - 4.72" / 120 mm 45.0 cal guns - 53.18lbs / 24.12kg shells, 320 per gun
	  Dual purpose guns in deck and hoist mounts, 1935 Model
	  8 x Twin mounts on sides, evenly spread
		4 raised mounts
      16 - 1.57" / 40.0 mm 39.0 cal guns - 1.85lbs / 0.84kg shells, 2,500 per gun
	  Anti-air guns in deck mounts, 1935 Model
	  8 x Twin mounts on sides, evenly spread
		4 raised mounts
      24 - 0.98" / 25.0 mm 50.0 cal guns - 0.51lbs / 0.23kg shells, 10,000 per gun
	  Anti-air guns in deck mounts, 1935 Model
	  12 x Twin mounts on sides, evenly spread
		8 raised mounts
      Weight of broadside 4,911 lbs / 2,228 kg

Armour:
   - Belts:		Width (max)	Length (avg)		Height (avg)
	Main:	6.69" / 170 mm	495.41 ft / 151.00 m	9.84 ft / 3.00 m
	Ends:	Unarmoured
	  Main Belt covers 117 % of normal length

   - Torpedo Bulkhead - Additional damage containing bulkheads:
		1.97" / 50 mm	413.39 ft / 126.00 m	13.12 ft / 4.00 m
	Beam between torpedo bulkheads 70.54 ft / 21.50 m

   - Hull void:
		0.00" / 0 mm	  0.00 ft / 0.00 m	0.00 ft / 0.00 m

   - Gun armour:	Face (max)	Other gunhouse (avg)	Barbette/hoist (max)
	Main:	9.06" / 230 mm	5.91" / 150 mm		7.68" / 195 mm
	2nd:	0.79" / 20 mm	      -			      -

   - Armoured deck - multiple decks:
	For and Aft decks: 4.33" / 110 mm

   - Conning towers: Forward 3.94" / 100 mm, Aft 0.00" / 0 mm

Machinery:
	Oil fired boilers, steam turbines, 
	Electric motors, 2 shafts, 115,271 shp / 85,992 Kw = 32.00 kts
	Range 6,000nm at 15.00 kts
	Bunker at max displacement = 1,934 tons

Complement:
	771 - 1,003

Cost:
	£7.729 million / $30.918 million

Distribution of weights at normal displacement:
	Armament: 1,447 tons, 8.1 %
	   - Guns: 1,447 tons, 8.1 %
	Armour: 4,750 tons, 26.6 %
	   - Belts: 1,313 tons, 7.4 %
	   - Torpedo bulkhead: 395 tons, 2.2 %
	   - Armament: 1,041 tons, 5.8 %
	   - Armour Deck: 1,943 tons, 10.9 %
	   - Conning Tower: 58 tons, 0.3 %
	Machinery: 3,275 tons, 18.3 %
	Hull, fittings & equipment: 6,258 tons, 35.0 %
	Fuel, ammunition & stores: 1,915 tons, 10.7 %
	Miscellaneous weights: 210 tons, 1.2 %
	   - Hull void weights: 150 tons
	   - On freeboard deck: 20 tons
	   - Above deck: 40 tons

Overall survivability and seakeeping ability:
	Survivability (Non-critical penetrating hits needed to sink ship):
	  22,322 lbs / 10,125 Kg = 52.9 x 9.4 " / 240 mm shells or 3.2 torpedoes
	Stability (Unstable if below 1.00): 1.11
	Metacentric height 4.1 ft / 1.3 m
	Roll period: 15.9 seconds
	Steadiness	- As gun platform (Average = 50 %): 55 %
			- Recoil effect (Restricted arc if above 1.00): 0.54
	Seaboat quality  (Average = 1.00): 1.10

Hull form characteristics:
	Hull has rise forward of midbreak,
	  a normal bow and a cruiser stern
	Block coefficient (normal/deep): 0.434 / 0.440
	Length to Beam Ratio: 8.46 : 1
	'Natural speed' for length: 25.49 kts
	Power going to wave formation at top speed: 54 %
	Trim (Max stability = 0, Max steadiness = 100): 50
	Bow angle (Positive = bow angles forward): 12.00 degrees
	Stern overhang: 4.92 ft / 1.50 m
	Freeboard (% = length of deck as a percentage of waterline length):
				Fore end,	 Aft end
	   - Forecastle:	20.00 %,  27.56 ft / 8.40 m,  24.61 ft / 7.50 m
	   - Forward deck:	45.00 %,  24.61 ft / 7.50 m,  21.65 ft / 6.60 m
	   - Aft deck:	15.00 %,  14.44 ft / 4.40 m,  14.44 ft / 4.40 m
	   - Quarter deck:	20.00 %,  14.44 ft / 4.40 m,  14.44 ft / 4.40 m
	   - Average freeboard:		20.62 ft / 6.28 m
	Ship tends to be wet forward

Ship space, strength and comments:
	Space	- Hull below water (magazines/engines, low = better): 94.0 %
		- Above water (accommodation/working, high = better): 162.6 %
	Waterplane Area: 31,411 Square feet or 2,918 Square metres
	Displacement factor (Displacement / loading): 110 %
	Structure weight / hull surface area: 142 lbs/sq ft or 696 Kg/sq metre
	Hull strength (Relative):
		- Cross-sectional: 0.94
		- Longitudinal: 1.65
		- Overall: 1.00
	Adequate machinery, storage, compartmentation space
	Excellent accommodation and workspace room

Anybody got any other ideas how I could reasonably improve surviability against torpedoes without changing the ships dimensions and displacement and preferably without reducing her performance and combat abilities further? I've always found ships of this type are far more challenging than a battleship to get right. She has to be able to engage the 8in Myokos and Takaos (and future Mogamis) with good chances of defeating them without sustaining damage that would cripple her.

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"The first rule is not to lose; The second rule is not to forget the first rule"

A TDS is the best way to do that, beyond that I don't think there's much you can do short of increasing armor - which isn't practical for this design. Battleships are quite survivable, anything smaller has to be considered expendable unless you make protection a priority in which case you sacrifice speed, firepower or both...

Well I've experimented some more but I haven't found any other means to give greater survival against torpedoes beyond the existing arrangement without unbalancing the design. As it stands the vessel has much greater protection than her Japanese rivals and has a somewhat heavier shell from her nine guns to counter the greater number of 8in shells from the IJN cruisers.

Her speed as it is can't really be altered as otherwise she wouldn't have the speed to carry out her role. 32 knots is about the same average speed recorded by the Japanese vessels in operational conditions and the North Pacific is notorious for low visibility and bad weather.

Also unlike the Japanese vessels, I opted not to include torpedo armament on this design as the space available is limited and torpedoes represent a weak point in a ships defenses if hit. Besides, considering these vessels are intended to operate in conjunction with an escort of destroyers, its more effective to leave the torpedoes to them as they are a harder target to hit than a cruiser and carry a heavier torpedo armament.

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"The first rule is not to lose; The second rule is not to forget the first rule"

Well, it's still quite impressive. And I think they will make a definite impression on any foes!

Thanks. They may not be capital ships through technical means (guns over 10in) but they would be the most potent Sieranian vessels in service at the time and serve as flagships. They're as balanced as I think I can get them, certainly more so than the treaty cruisers that would be their opponents.

Whilst her torpedo defenses aren't perfect, her armour seems quite effective. From the navweaps page on the Japanese 20cm/50 gun that armed most of their heavy cruisers. The standard AP shell of theirs would be unable to penetrate the main belt unless at ranges below 10,000m. Deck penetration information isn't available so I can't assess that but it seems as long as the Japanese cruisers can be kept at a distance, she should be fine. Not sure how she'd fare against a Kongo but I have no information on those guns. I can guess it wouldn't be pretty however.

Just need to finalise the main armaments positioning as either majority forward or majority aft. I'm thinking majority forward would work best.

_________________
"The first rule is not to lose; The second rule is not to forget the first rule"

I'm really exited to see how these cruisers will look! Will the two units be identical at commissioning or will they appear different?

The two ships (still deciding upon their names) would be built to a common design however they would likely be different in some ways due to being built at slightly different times (about 6 months apart between keel laying). The most likely differences would be in sensor equipment fits (early surface detection radar vs air detection) and minor things dictated by economics during construction.

The intended aim for them would be that one would be available at all times for sea.

I've got an idea of how they will look however I'm first trying to finish my top view of the SRN Lazarev and the large destroyers designed to escort the C3s.

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"The first rule is not to lose; The second rule is not to forget the first rule"

Ooh! Large destroyers! Another thing to look forward too!

They're about the same size as the Zerstörer 1936A destroyers of Germany only more seaworthy for operations in the Bering Sea. They need to be large to have the endurance and seakeeping whilst retaining the high speed of a destroyer. Debating triple or quadruple tube deck mounts on pivots for their torpedo armament.

_________________
"The first rule is not to lose; The second rule is not to forget the first rule"

Shipbucket

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