Battleships

[Delta Force]

Can you purchase turrets and guns from a foreign power for installation on a warship? I am thinking of purchasing 16.5 inch guns and turrets direct from Skoda in order to expedite the entry into service of the treaty battleships, especially since the majority of ships will be limited by tonnage limits to 15 inch guns.

[Sachmle]

Yes.

[Delta Force]

So, I'm redesigning the armor configuration on my future fast battleships. If you have actual torpedo bulges (I have 2 meters on each side), isn't 2 inches of armor actually detrimental? Someone told me Yamato had around that much and the bulges ended up being too resistant to deforming, so instead they just failed and became more shrapnel after a torpedo hit.

[Logi]

From my thread:

Well, I meant in reference to battle damage. The ship does seem to be vulnerable to capsizing after suffering underwater damage.

That's in your imagination. That's the level of comparing a standard to the Richelieu and saying the Richelieu has a less robust underwater defense so it must capsize after an underwater hit. Yes, my design is less sturdy than your (larger) more armored ship, but it is not "terribly prone to capsizing".

But that may only be in reference to my design style with two meter thick torpedo blisters on each side. I have noticed that I am the only one using torpedo blisters on my designs, but my bulkhead strength itself does seem to be a tad lighter than those others use (2 inches, while I seen them up to 2.5 or 3.5 inches).

Very thick bulkheads are counter-productive. They cause more damage to the ship than it absorbs. That is why I try to use only 1.5" thick TDS. Other than actual things that happen when bulkheads are too thick, you can see yourself there is a huge diminishing return once you past 1" thick TDS in SS.

Also, I forgot why, but we hate Torpedo blisters here.

1. Actually I use torpedo blisters as well, as that fits the development level of my naval designers.  Blisters do have negatives IRL* and P3D has observed SS2 doesn't do them right- I think his point is that adding blisters doesn't effect the ship's structural allocation properly.  

2. As for thickness- most people here sim the holding bulkhead alone.  The bulkheads separating internal compartments are not generally included. Perhaps they should, but they are not.   Interior bulkheads are not built from the same type of armor steel as the main belt, they are meant to deform greatly and then tear- not shatter.  As a result, thick single bulkheads are indeed undesirable as they are too thick to stretch instead of rupture. Plus historically the stiffer bulkheads in SoDak and Yamato had joint problems trying to balance the stretch/break issue.    To thin and you risk perforation by ejected parts of the hull and structure on the surface of the blast.



*Negatives include : gas bubble doesn't vent up as much, if void space then prone to off-center flooding, the wider they are, the further away from the belt a "short" round can enter the hull and dive inside the hull, and of course they slow down the vessel by increasing surface area.

[Valles]

So, I'm redesigning the armor configuration on my future fast battleships. If you have actual torpedo bulges (I have 2 meters on each side), isn't 2 inches of armor actually detrimental? Someone told me Yamato had around that much and the bulges ended up being too resistant to deforming, so instead they just failed and became more shrapnel after a torpedo hit.

Given the limitations of Springsharp, it would count two one-inch bulkheads as being two inches of bulkhead armor; specifying further details to that degree would be included in the 'designer's notes'. For example, Cross Mirage carries a total of 75mm of high-tensile steel... in three bulkheads, each separated first from the outer hull, then from the previous bulkhead, by both void and liquid-filled separation spaces. I'm not sure exactly how that'd stack up to historical systems - no one seems to've used that exact approach - but I expect it to do fairly well.

[Delta Force]

I reduced the underwater protection (2 inches seemed a tad thick for a ship with 2 meter wide torpedo bulges on each side), added more oil, increased speed by a quarter knot, and took away the internal ends armor in favor of external armor all around (to protect the whole ship against 6 inch shells and splinters). I figured that there wasn't much point in having 4 inches of internal armor on the ends since at that point it is damage control as opposed to systems protection, and also because 4 inches and 2.5 inches protect against the same types of shells.

15 Inch Battleshipv5, CSA Battleship laid down 1920

Displacement:
   35,000 t light; 36,937 t standard; 40,208 t normal; 42,824 t full load

Dimensions: Length overall / water x beam x draught
   721.78 ft / 721.78 ft x 104.99 ft (Bulges 118.11 ft) x 28.87 ft (normal load)
   220.00 m / 220.00 m x 32.00 m (Bulges 36.00 m)  x 8.80 m

Armament:
      8 - 15.00" / 381 mm guns (4x2 guns), 2,000.00lbs / 907.18kg shells, 1920 Model
     Breech loading guns in turrets (on barbettes)
     on centreline ends, evenly spread, 2 raised mounts - superfiring
      16 - 4.75" / 121 mm guns (8x2 guns), 50.00lbs / 22.68kg shells, 1920 Model
     Quick firing guns in deck mounts with hoists
     on side, all amidships, 4 raised mounts - superfiring
      4 - 1.58" / 40.0 mm guns in single mounts, 2.00lbs / 0.91kg shells, 1920 Model
     Breech loading guns in deck mounts
     on centreline ends, evenly spread, all raised mounts - superfiring
   Weight of broadside 16,808 lbs / 7,624 kg
   Shells per gun, main battery: 120

Armour:
   - Belts:      Width (max)   Length (avg)      Height (avg)
   Main:   13.5" / 343 mm   470.00 ft / 143.26 m   17.56 ft / 5.35 m
   Ends:   Unarmoured
   Upper:   2.50" / 64 mm   721.78 ft / 220.00 m   16.50 ft / 5.03 m
     Main Belt covers 100 % of normal length

   - Torpedo Bulkhead and Bulges:
      1.00" / 25 mm   470.00 ft / 143.26 m   32.15 ft / 9.80 m

   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   16.0" / 406 mm   7.00" / 178 mm      13.5" / 343 mm
   2nd:   1.50" / 38 mm   1.00" / 25 mm      3.00" / 76 mm

   - Armour deck: 3.00" / 76 mm, Conning tower: 16.00" / 406 mm

Machinery:
   Oil fired boilers, steam turbines,
   Electric motors, 4 shafts, 116,000 shp / 86,536 Kw = 27.75 kts
   Range 16,000nm at 12.00 kts
   Bunker at max displacement = 5,888 tons

Complement:
   1,419 - 1,845

Cost:
   £7.803 million / $31.211 million

Distribution of weights at normal displacement:
   Armament: 1,796 tons, 4.5 %
   Armour: 13,099 tons, 32.6 %
      - Belts: 5,936 tons, 14.8 %
      - Torpedo bulkhead: 559 tons, 1.4 %
      - Armament: 3,203 tons, 8.0 %
      - Armour Deck: 2,996 tons, 7.5 %
      - Conning Tower: 405 tons, 1.0 %
   Machinery: 4,056 tons, 10.1 %
   Hull, fittings & equipment: 15,648 tons, 38.9 %
   Fuel, ammunition & stores: 5,207 tons, 13.0 %
   Miscellaneous weights: 402 tons, 1.0 %

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     55,039 lbs / 24,965 Kg = 32.6 x 15.0 " / 381 mm shells or 9.1 torpedoes
   Stability (Unstable if below 1.00): 1.08
   Metacentric height 6.3 ft / 1.9 m
   Roll period: 19.8 seconds
   Steadiness   - As gun platform (Average = 50 %): 70 %
         - Recoil effect (Restricted arc if above 1.00): 0.49
   Seaboat quality  (Average = 1.00): 1.09

Hull form characteristics:
   Hull has raised forecastle
   Block coefficient: 0.572
   Length to Beam Ratio: 6.11 : 1
   'Natural speed' for length: 26.87 kts
   Power going to wave formation at top speed: 52 %
   Trim (Max stability = 0, Max steadiness = 100): 64
   Bow angle (Positive = bow angles forward): 0.00 degrees
   Stern overhang: 0.00 ft / 0.00 m
   Freeboard (% = measuring location as a percentage of overall length):
      - Stem:      31.17 ft / 9.50 m
      - Forecastle (20 %):   24.61 ft / 7.50 m (21.33 ft / 6.50 m aft of break)
      - Mid (50 %):      21.33 ft / 6.50 m
      - Quarterdeck (15 %):   21.33 ft / 6.50 m
      - Stern:      21.33 ft / 6.50 m
      - Average freeboard:   22.51 ft / 6.86 m

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 85.0 %
      - Above water (accommodation/working, high = better): 154.5 %
   Waterplane Area: 53,976 Square feet or 5,014 Square metres
   Displacement factor (Displacement / loading): 112 %
   Structure weight / hull surface area: 205 lbs/sq ft or 1,003 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.96
      - Longitudinal: 1.31
      - Overall: 1.00
   Hull space for machinery, storage, compartmentation is adequate
   Room for accommodation and workspaces is excellent
   Ship has slow, easy roll, a good, steady gun platform

Main belt armor sloped 20 degrees, giving a vertical height of 16.5 feet. Relative thickness to a 90 degree impact is 14.37 inches.

"Upper" belt armor is external armor. It is meant to provide areas outside of the citadel protection against shell splinters and 6 inch and lighter shells.

Misc Weight (402 tons):
250 tons fire control system
25 tons radar
25 tons long range wireless
25 tons night fighting gear
25 tons crane and catapult for floatplane
10 tons 2x floatplanes
42 tons reserve

[Sachmle]

So your TDS is one single 25mm bulkhead? Wouldn't a layered system work better?

[Delta Force]

So your TDS is one single 25mm bulkhead? Wouldn't a layered system work better?

Yeah, I was hoping for input on that. It's hard to find information on underwater protection as opposed to belts and such.

[Sachmle]

From "Torpedo Defense Systems of World War II" by Joseph Czarnecki

As World War I progressed and ships began to experience underwater damage from mines and torpedoes, designers strove to create the most effective TDS possible.  Across the Atlantic, where the US was still at peace, careful, conservative designers produced one of the structurally most sound torpedo defense systems ever devised, introducing it in the 1915 design for the Tennessee Class battleships.

The five-layer system took advantage of the reduced beam requirements of the turbo-electric drive system also planned for the Tennessee Class.  This permitted the designers to give the system more all-important depth.  The outermost and innermost layers were left void, with the three middle layers liquid-loaded.  The novelty of the system lay in three thin, highly elastic armored bulkheads fitted between the four innermost layers.

Each bulkhead was carefully designed to provide maximum resistance to overpressure before tearing.  The bulkheads were spaced so that once torn, a failed bulkhead would not impinge upon the next bulkhead inboard, permitting that structure in turn to provide maximum resistance, undamaged by the preceding structure.  Similarly, the last armored bulkhead would not impinge on the holding bulkhead.  The collective resistance of the three armored bulkheads and liquid layers stopped fragments before they could reach the unarmored holding bulkhead.

[TexanCowboy]

IMHO, it's more of a physics thing than it is a "naval historical" thing. A single layer of steel will never be as effective at stopping a torpedo as several layers, each having water to absorb some of the explosion. It's not like a shell, where thick armour is more likely to help; several layers of about 20 mm each would be much more effective.

[Sachmle]

I think 20mm may even be to rigid. Perhaps 8-10mm honestly.

[TexanCowboy]

I think the standards used 20 mm, and they held up pretty well at Pearl Harbor. Anyone have the data on the thickness of the outer hull of an Akula?

[Kaiser Kirk]

Deep in the discussion of the effectiveness of Bismarck's guns vs. various ships there is a detailing of various underwater systems prepartory to addressing diving shells.

From that :
Torpedo Bulkheads :
Vittorio Veneto : 40mm holding bulkhead
Bismarck :  12.7mm-19mm compartment bulkheads, 45mm holding bulkhead.
KGV : 19-22mm (Since the system seems to have been designed badly overall, I'd say this is a good minimum)
SoDak :  3 x 0.75" compartment bulkheads, main holding bulkhead : 287mm tapered 41mm  (hybrid holding & anti-diving shell) at 2.5ft above bottom, then 0.75mm until bottom.
Yamato : 200 tapered to 76.2mm (hybrid holding & anti-diving shell)

ed: Richeliu : 38mm holding bulkhead.

[Sachmle]

So a layered system, such as SoDak (0.75"/19mm x3 + 41mm = 98mm) would have a value much higher than most of our systems, yet once someone goes over 60-70mm people start screaming "It's too thick". Weird.

[Delta Force]

Is the torpedo bulkhead too tall? It's 8.8 meters plus another meter.