Battleships

[Kaiser Kirk]

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.

Thats because people only seem to be modeling the main holding bulkhead here.

So if that's the only one we're expecting to see- and it's the one easiest to find listed in reference material-  then a SS2 "98mm" would seem to thick, after all Yamato's 76.2mm was "to thick". 

It's probably an area we should just all agree not to count the partition thicknesses, and just show the main holding bulkhead.  For one thing - there is dramatically diminishing returns in SS2 between simply having TDS and not, regardless of thickness- so it's not "seeing" the compartments, just the main holding bulkhead. 

[Sachmle]

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

Not necessarily. A few nations, Germany comes to mind, carried the TDS above the waterline. Bismarck's TDS continued above deck behind the main and upper belts as a 25-30mm internal bulkhead to catch/slow splinters from belt hits.

[Delta Force]

New and improved. It's lost about a knot and a half in speed, but now has the best torpedo protection system around.

15 Inch Battleshipv6, 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:   2.00" / 51 mm   721.78 ft / 220.00 m   16.50 ft / 5.03 m
     Main Belt covers 100 % of normal length

   - Torpedo Bulkhead and Bulges:
      3.00" / 76 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, 92,000 shp / 68,632 Kw = 26.16 kts
   Range 16,000nm at 12.00 kts
   Bunker at max displacement = 5,888 tons

Complement:
   1,419 - 1,845

Cost:
   £7.525 million / $30.101 million

Distribution of weights at normal displacement:
   Armament: 1,796 tons, 4.5 %
   Armour: 13,995 tons, 34.8 %
      - Belts: 5,714 tons, 14.2 %
      - Torpedo bulkhead: 1,677 tons, 4.2 %
      - Armament: 3,203 tons, 8.0 %
      - Armour Deck: 2,996 tons, 7.5 %
      - Conning Tower: 405 tons, 1.0 %
   Machinery: 3,217 tons, 8.0 %
   Hull, fittings & equipment: 15,565 tons, 38.7 %
   Fuel, ammunition & stores: 5,207 tons, 13.0 %
   Miscellaneous weights: 428 tons, 1.1 %

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     62,764 lbs / 28,469 Kg = 37.2 x 15.0 " / 381 mm shells or 12.9 torpedoes
   Stability (Unstable if below 1.00): 1.15
   Metacentric height 7.0 ft / 2.1 m
   Roll period: 18.7 seconds
   Steadiness   - As gun platform (Average = 50 %): 70 %
         - Recoil effect (Restricted arc if above 1.00): 0.46
   Seaboat quality  (Average = 1.00): 1.25

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: 49 %
   Trim (Max stability = 0, Max steadiness = 100): 56
   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): 76.8 %
      - Above water (accommodation/working, high = better): 154.5 %
   Waterplane Area: 53,976 Square feet or 5,014 Square metres
   Displacement factor (Displacement / loading): 114 %
   Structure weight / hull surface area: 204 lbs/sq ft or 998 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.96
      - Longitudinal: 1.34
      - Overall: 1.00
   Hull space for machinery, storage, compartmentation is excellent
   Room for accommodation and workspaces is excellent
   Ship has slow, easy roll, a good, steady gun platform
   Good seaboat, rides out heavy weather easily

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.

Torpedo defense system consists of three compartment bulkheads of 0.5 inches and a holding bulkhead of 1.5 inches.

Misc Weight (428 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
68 tons reserve

[Logi]

It's lost about a knot and a half in speed, but now has the best torpedo protection system around.

I believe the sloped armor with blisters offset the good TDS layout.

Torpedo defense system consists of three compartment bulkheads of 0.5 inches and a holding bulkhead of 1.5 inches.

SS only counts the Holding bulkhead. Your numbers in the TDS thickness are delegated to holding bulkhead thickness and aren't separated into internal compartments.

It's probably an area we should just all agree not to count the partition thicknesses, and just show the main holding bulkhead.  For one thing - there is dramatically diminishing returns in SS2 between simply having TDS and not, regardless of thickness- so it's not "seeing" the compartments, just the main holding bulkhead. 

[snip]

It's lost about a knot and a half in speed, but now has the best torpedo protection system around.

I believe the sloped armor with blisters offset the good TDS layout.

Yes, lots of nice unarmored space to introduce a nice list and tip the whole ship over. Bulges+Inclined belts=easy capsizing. In fact, bulges on new construction is never a good idea IMO, as it creates area that is completely unarmored and can be esaly flooded by almost any gun. Giving that much mass in water to one side is all but guaranteed to capsize the ship if said flooding is uncontrollable. Whatever standoff distance advantages for torpedo impacts they provide are more then offset by this.

[Delta Force]

The California, Tennessee, and West Virginia were all fitted with similar torpedo bulges during World War II. None of them were actually hit by torpedoes after Pearl Harbor though. That said, the entire torpedo bulge would have to be ruptured all along its length for this to be a problem, which would require the ship to essentially steam right into a torpedo barrage. However, they were already 35,000 tons before receiving their bulges.

Now, I realize that the weight is being added to the top and center of the ship, but this ship is so buoyant that it could hold an additional 3,500 tons and still be able to ride out a decent sized storm (obviously there would still be hull strain) with a stability of 1.09. I'm not sure how it would look with asymmetric flooding below the waterline, but since each bulge is around 2,000 tons (and bulges usually contain some water, oil, and/or other liquids in addition to air), I think that the danger of the ship capsizing from damage to its own torpedo bulges is unlikely.

[TexanCowboy]

The California, Tennessee, and West Virginia were all fitted with similar torpedo bulges during World War II. None of them were actually hit by torpedoes after Pearl Harbor though. That said, the entire torpedo bulge would have to be ruptured all along its length for this to be a problem, which would require the ship to essentially steam right into a torpedo barrage. However, they were already 35,000 tons before receiving their bulges.

As an interim measure, since it's near impossible to add a TB onto existing constructure. And, more realistically, you'll be filling the bulges with fuel oil, as extra fuel tanks...so; not so much, easy to break through.

Now, I realize that the weight is being added to the top and center of the ship, but this ship is so buoyant that it could hold an additional 3,500 tons and still be able to ride out a decent sized storm (obviously there would still be hull strain) with a stability of 1.09.

If you have 1.00 stability, a single hit on a bulkhead or anything, really, will cause capsizing. 1.09 is low, by my standards, for battleships. (I prefer 1.15).

[snip]

Also, those ships you site did not have inclined belts. That is were my issue with this design arises.

[Delta Force]

What's the problem with inclined belts? If it is a major design weakness, I can always make it a perfectly vertical armor belt or reduce the incline.

[snip]

its not a design weakness in itself, but combining it with bulges leaves huge unarmed areas that are way of to the sides of the center of gravity. You are basically inviting some ship to blast so many holes in the unarmored portion of as side so as to let in a sufficient amount of water to capsize your ship, despite its exilent stability rating.

[TexanCowboy]

And the stability isn't really even all that good...

[Delta Force]

Getting stability and seaworthiness up is somewhat problematic. The metacentric height of the ship is already pretty high.

[Kaiser Kirk]

External bulges were used prior to internal TDS bulges and were generally supplanted by them.  You seem them come back later both as a means of enhancing torpedo defense, and of enhancing floatation.  

External bulges were subdivided in their own right and often had fuel oil stored in them. However they increase the beam of the ship  and create drag etc- not friendly to water flow and overall slowing the vessel. A major reason they went internal in the first place.

Theoretically, they would give some standoff distance for external venting of the gas bubble of a torpedo explosion. From what I understand, that didn't work as hoped, but that part wasn't known in this time frame. Hence why the Bavarians are using it- they are new to large ship construction, seems like a safe bet.

In terms of internal sloped belts and bulges the problem is simple- a "short" round will dive only a limited distance before tumbling over and proceeding base first- rendering it non-menacing.  Now, if you have a 'shelf' of a bulge sticking out, a short can now land further out and penetrate the hull without tumbling. Since it will be at a downward trajectory, it can now dive further, allowing it a better chance of going under an internal belt.  

As for problems with the sloped internal belt- minor ones include the ability to turn the outer hull into swiss cheese via HE and let water pour in- part of why the USN thickened the STS hull plating which had the secondary decapping effect - and the reason I believe I once...way back in college... read for the RN to abandon the sloped belts of Nelson for the vertical of KGV - a shell already diving that enters the hull, and hits the sloped belt, can then be deflected- armed - into the bowels of the ship. Between simple diving angles and deflections there are certain limited but real paths where a shell can pass completely through the TDS portion and into the vitals, avoiding anything thicker than the holding bulkhead.   Of course at this distance in time, I could be misremembering.

[P3D]

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.

It's not the water or steel that "stops" the blast, but the alternating layers of liquid and air. The steel is only there to separate the compartments.
A TDS filled with liquid only would only reduce the blast due to distances traveled.
The holding bulkhead is there to stop splinters coming from the separating bulkheads.

[Delta Force]

I do have a 2 inch external belt that runs the length of the ship. Obviously it can't hold up against a main battery shell, but it offers good protection against 6 inch and smaller shells at distances of around 11,000 yards and further out. So I don't have to worry about the outer areas of the ship being penetrated by the small secondary battery shells. That leaves deflection trajectories as the only possible problem, and I am not sure if the risk of that happening (not sure how likely it is) is worth trading 0.87 inches of line of sight armor.