Leviathan

[mentat]

  As we approach 1920s - BBs seem to be heading closer to the 40k ton mark - so I'm interested to see what can be had for that kind of investment.

Here goes:

Firstly - heavy on Firepower and Protection - but being sensible - at only 25 knots:

  The 17.25 inch calibre gives a good advantage over 16" - but without going too far I think ...

  (why did no one ever go for 17" - puzzling)

Leviathan I, BAE  Large BB laid down 1918

Displacement:
   40,135 t light; 42,380 t standard; 44,787 t normal; 46,713 t full load

Dimensions: Length overall / water x beam x draught
   794.83 ft / 785.00 ft x 116.14 ft x 32.75 ft (normal load)
   242.26 m / 239.27 m x 35.40 m  x 9.98 m

Armament:
      8 - 17.25" / 438 mm guns (3 mounts), 2,850.00lbs / 1,292.74kg shells, 1918 Model
     Breech loading guns in turrets (on barbettes)
     on centreline ends, majority forward, 1 raised mount - superfiring
      16 - 5.20" / 132 mm guns (8x2 guns), 70.00lbs / 31.75kg shells, 1918 Model
     Quick firing guns in deck mounts with hoists
     on side, all amidships, 4 raised mounts - superfiring
      6 - 3.15" / 80.0 mm guns in single mounts, 15.00lbs / 6.80kg shells, 1918 Model
     Anti-aircraft guns in deck mounts
     on side, evenly spread, all raised mounts
      32 - 1.06" / 27.0 mm guns (8x4 guns), 0.60lbs / 0.27kg shells, 1918 Model
     Machine guns in deck mounts
     on side, evenly spread, all raised mounts
   Weight of broadside 24,029 lbs / 10,899 kg
   Shells per gun, main battery: 100

Armour:
   - Belts:      Width (max)   Length (avg)      Height (avg)
   Main:   15.0" / 381 mm   450.00 ft / 137.16 m   12.00 ft / 3.66 m
   Ends:   Unarmoured
   Upper:   3.00" / 76 mm   280.00 ft / 85.34 m   10.00 ft / 3.05 m
     Main Belt covers 88 % of normal length

   - Torpedo Bulkhead:
      1.80" / 46 mm   500.00 ft / 152.40 m   34.00 ft / 10.36 m

   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   15.0" / 381 mm   7.00" / 178 mm      14.0" / 356 mm
   2nd:   2.00" / 51 mm   1.50" / 38 mm      2.50" / 64 mm
   3rd:   1.20" / 30 mm   1.00" / 25 mm            -
   4th:   0.80" / 20 mm   0.80" / 20 mm            -

   - Armour deck: 5.50" / 140 mm, Conning tower: 15.00" / 381 mm

Machinery:
   Oil fired boilers, steam turbines,
   Geared drive, 4 shafts, 77,854 shp / 58,079 Kw = 25.00 kts
   Range 10,000nm at 12.00 kts
   Bunker at max displacement = 4,333 tons

Complement:
   1,539 - 2,001

Cost:
   £8.167 million / $32.670 million

Distribution of weights at normal displacement:
   Armament: 2,721 tons, 6.1 %
   Armour: 15,501 tons, 34.6 %
      - Belts: 4,030 tons, 9.0 %
      - Torpedo bulkhead: 1,132 tons, 2.5 %
      - Armament: 3,606 tons, 8.1 %
      - Armour Deck: 6,325 tons, 14.1 %
      - Conning Tower: 408 tons, 0.9 %
   Machinery: 2,809 tons, 6.3 %
   Hull, fittings & equipment: 18,704 tons, 41.8 %
   Fuel, ammunition & stores: 4,652 tons, 10.4 %
   Miscellaneous weights: 400 tons, 0.9 %

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     60,395 lbs / 27,395 Kg = 23.5 x 17.3 " / 438 mm shells or 10.4 torpedoes
   Stability (Unstable if below 1.00): 1.10
   Metacentric height 7.5 ft / 2.3 m
   Roll period: 17.8 seconds
   Steadiness   - As gun platform (Average = 50 %): 70 %
         - Recoil effect (Restricted arc if above 1.00): 0.57
   Seaboat quality  (Average = 1.00): 1.23

Hull form characteristics:
   Hull has rise forward of midbreak
   Block coefficient: 0.525
   Length to Beam Ratio: 6.76 : 1
   'Natural speed' for length: 28.02 kts
   Power going to wave formation at top speed: 42 %
   Trim (Max stability = 0, Max steadiness = 100): 57
   Bow angle (Positive = bow angles forward): 20.00 degrees
   Stern overhang: 0.00 ft / 0.00 m
   Freeboard (% = measuring location as a percentage of overall length):
      - Stem:      27.00 ft / 8.23 m
      - Forecastle (20 %):   23.00 ft / 7.01 m
      - Mid (50 %):      23.00 ft / 7.01 m (15.00 ft / 4.57 m aft of break)
      - Quarterdeck (15 %):   15.00 ft / 4.57 m
      - Stern:      17.00 ft / 5.18 m
      - Average freeboard:   19.47 ft / 5.93 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 81.7 %
      - Above water (accommodation/working, high = better): 143.8 %
   Waterplane Area: 62,158 Square feet or 5,775 Square metres
   Displacement factor (Displacement / loading): 103 %
   Structure weight / hull surface area: 227 lbs/sq ft or 1,110 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.98
      - Longitudinal: 1.24
      - 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


I've been think ing that a Fast BB (28+ knots) will mean restricting to 15" calibre for under 40k tons - but actually not too many sacrifices seem to be required to up the speed - thinning the strong deck and belt by an inch a piece mostly do it

Leviathan II , BAE  Large Fast BB laid down 1918

Displacement:
   40,135 t light; 42,380 t standard; 44,787 t normal; 46,713 t full load

Dimensions: Length overall / water x beam x draught
   794.83 ft / 785.00 ft x 116.14 ft x 32.75 ft (normal load)
   242.26 m / 239.27 m x 35.40 m  x 9.98 m

Armament:
      8 - 17.25" / 438 mm guns (3 mounts), 2,850.00lbs / 1,292.74kg shells, 1918 Model
     Breech loading guns in turrets (on barbettes)
     on centreline ends, majority forward, 1 raised mount - superfiring
      16 - 5.20" / 132 mm guns (8x2 guns), 70.00lbs / 31.75kg shells, 1918 Model
     Quick firing guns in deck mounts with hoists
     on side, all amidships, 4 raised mounts - superfiring
      6 - 3.15" / 80.0 mm guns in single mounts, 15.00lbs / 6.80kg shells, 1918 Model
     Anti-aircraft guns in deck mounts
     on side, evenly spread, all raised mounts
      32 - 1.06" / 27.0 mm guns (8x4 guns), 0.60lbs / 0.27kg shells, 1918 Model
     Machine guns in deck mounts
     on side, evenly spread, all raised mounts
   Weight of broadside 24,029 lbs / 10,899 kg
   Shells per gun, main battery: 100

Armour:
   - Belts:      Width (max)   Length (avg)      Height (avg)
   Main:   14.0" / 356 mm   498.00 ft / 151.79 m   12.00 ft / 3.66 m
   Ends:   Unarmoured
     Main Belt covers 98 % of normal length

   - Torpedo Bulkhead:
      1.50" / 38 mm   500.00 ft / 152.40 m   34.00 ft / 10.36 m

   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   15.0" / 381 mm   7.00" / 178 mm      14.0" / 356 mm
   2nd:   2.00" / 51 mm   1.50" / 38 mm      2.50" / 64 mm
   3rd:   1.20" / 30 mm   1.00" / 25 mm            -
   4th:   0.80" / 20 mm   0.80" / 20 mm            -

   - Armour deck: 4.25" / 108 mm, Conning tower: 15.00" / 381 mm

Machinery:
   Oil fired boilers, steam turbines,
   Geared drive, 4 shafts, 128,484 shp / 95,849 Kw = 28.50 kts
   Range 10,000nm at 12.00 kts
   Bunker at max displacement = 4,333 tons

Complement:
   1,539 - 2,001

Cost:
   £8.679 million / $34.716 million

Distribution of weights at normal displacement:
   Armament: 2,721 tons, 6.1 %
   Armour: 13,484 tons, 30.1 %
      - Belts: 3,639 tons, 8.1 %
      - Torpedo bulkhead: 944 tons, 2.1 %
      - Armament: 3,606 tons, 8.1 %
      - Armour Deck: 4,887 tons, 10.9 %
      - Conning Tower: 408 tons, 0.9 %
   Machinery: 4,635 tons, 10.3 %
   Hull, fittings & equipment: 18,895 tons, 42.2 %
   Fuel, ammunition & stores: 4,652 tons, 10.4 %
   Miscellaneous weights: 400 tons, 0.9 %

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     50,744 lbs / 23,017 Kg = 19.8 x 17.3 " / 438 mm shells or 7.8 torpedoes
   Stability (Unstable if below 1.00): 1.10
   Metacentric height 7.5 ft / 2.3 m
   Roll period: 17.8 seconds
   Steadiness   - As gun platform (Average = 50 %): 60 %
         - Recoil effect (Restricted arc if above 1.00): 0.53
   Seaboat quality  (Average = 1.00): 1.02

Hull form characteristics:
   Hull has rise forward of midbreak
   Block coefficient: 0.525
   Length to Beam Ratio: 6.76 : 1
   'Natural speed' for length: 28.02 kts
   Power going to wave formation at top speed: 49 %
   Trim (Max stability = 0, Max steadiness = 100): 59
   Bow angle (Positive = bow angles forward): 20.00 degrees
   Stern overhang: 0.00 ft / 0.00 m
   Freeboard (% = measuring location as a percentage of overall length):
      - Stem:      27.00 ft / 8.23 m
      - Forecastle (20 %):   23.00 ft / 7.01 m
      - Mid (50 %):      23.00 ft / 7.01 m (15.00 ft / 4.57 m aft of break)
      - Quarterdeck (15 %):   15.00 ft / 4.57 m
      - Stern:      17.00 ft / 5.18 m
      - Average freeboard:   19.47 ft / 5.93 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 97.5 %
      - Above water (accommodation/working, high = better): 143.8 %
   Waterplane Area: 62,158 Square feet or 5,775 Square metres
   Displacement factor (Displacement / loading): 100 %
   Structure weight / hull surface area: 230 lbs/sq ft or 1,121 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.98
      - Longitudinal: 1.21
      - Overall: 1.00
   Hull space for machinery, storage, compartmentation is adequate
   Room for accommodation and workspaces is excellent

NB - Protection - Mags: +1"  Macinery: -1"  vs Average in the Sim.


  I really like this 2nd one - a good answer to Mondedor and some others being planned. I think the extra speed will make the ship much more versatile and useful in the long run

Anyone have better ideas on how to use 40k tons ?  :D

[The Rock Doctor]

The fast unit certainly does seem capable.

As to why 17" never caught on - maybe it wasn't any more difficult to jump up to 18" (issues of blast pressure and so forth notwithstanding).

[Borys]

Ahoj!
I like the slower one .. :)
As to the lack of 17" in OTL, that's easy to explain - WWI.

After Germany moved to 42cm around 1918, I suppose that France would have looked at this calibre.

Hand't the USN adopted the 12" after the 13", then it would had been the main suspect.

Borys

[maddox]

Hmmm,  I like the slower one.

But 25kts is a tad fast, and the secundaries not French enough.

Mentat, are you willing to up the main guns to 4xT2 18", slow the ship down to 22 kts- but with a cruise speed of 16 kts over 6000nm.

and the secundaries to 140mm 42 kg mount and hoist.  (2" 1" 3" armor)
600 tons misc weight please.  The admiral needs space for his granit winecellar.

[Guinness]

The truth is no caliber bigger than 16" ever actually caught on, with the exception of two guns on Furious and the Yamatos of course.

Someone dug up a great document about how the RN arrived at the 18" gun over a 16" and a 16.5" for prospective future construction late in the Great War. I think Borys posted it here a while back as well. I suspect that 18" remained the logical next step in many navies simply because the RN was committed to build them before the Washington Treaty.

Personally, I think it's instructive that two decades later the USN was perfectly happy to stick to the 16"L50 for the Montanas, even though work had been done to develop an 18" gun, and Montana probably could have carried 8 18" instead of 12 16" guns.

[maddox]

No WT here...  and 18" is a heavy slug to hit with.

Nverse French politicians see the logic in it.

[Tanthalas]

I think Rohan will continue to develop the 16" gun as our largest.  Ending up with a 16/50 on somthing like Montana.

[Valles]

The 'ultimate' Maori heavy gun is likely to be 400mm/L60. Given a lightish shell and the kind of overdesign I'm allotting tonnage for in the barbettes of Cross Mirage and the ships to follow her, it should be doable with minimal other modification.

Muzzle velocity should end up being... impressive.

[mentat]

Thanks for replies - i still like the fast one - with another 1500 tons to get back some of the armour shedded - I can see it as an early Montana

Maddox - your 22 knot  8 x 18" version seems very doable - will have a look at it later in the week

Think now I can see why 17" did not happen;

  UK usually looked at increments of 1.5" - 12 - 13.5 - 15

Then US + Japan leapfrogged UK by going to 16" - making 16.5" of marginal attractiveness - and leaving 18" in the frame

- does that get it right?

  Borys do you have the doc on WW! UK RN policy on that - sounds very interesting ...

Intentionally - the 2850lb 17.25" is only a bit bigger than the 2700 US 16" super heavy of the 1940s

  I'm thinking this 17.25 would be a 45-48 Calibre - and average MV - quite big enough

Most attempts at High MV didn't work well - excessive barrel wear, short barrel life and reduced accuracy

Also heavy slower shell plunges better - to strike the deck - both RN and USN went down that route - most effective weapon system - not flashiest gun stats ....

[Borys]

Ahoj!
Surprisingly many navies plan to stop at 16" - suspicious :)

As to the RN - I don't think I have anything specific. I'd agee that the move to 18" was due to the other navies contemplating 16"  (the Russian 16" was designed in Britain in 1914, so this calibre jump was "in the air").

However, a gun in 16,5" calibre was considered by the RN around 1920:
http://www.navweaps.com/Weapons/WNBR_18-45_mk2.htm

Borys

[Valles]

I've specifically based the 'Maori style' of gun off of a hybrid of German and Italian ones, the latter of which in real life did indeed experience accuracy issues.

Because of quality control problems with their shell manufacturers, not with the guns. When provided with high-grade 'test' shells, the Italian guns were as accurate as any anywhere in the world. The wear issues either call for frequent relining or, more likely, research into improved metallurgy for the purpose which will naturally produce barrel liners with slightly different characteristics than were called for in earlier and 'heavy shell' weapons.

My decision to stop at 400mm is actually driven by armor plate.

The thickest belts I've ever heard of were Yamato's 410mm ones, and I'm hopeful that even 1920 technology can be pushed to 400mm if I do something like pay a surcharge for a higher ratio of belt plates discarded by the quality control process... But I doubt I'm going to do any better than that. So, by my concept of balanced design, that's as big as the guns get.

[Walter]

Thickest belt I can think of...

... ~18" on the Fuji class. Of course it is not the same quality as Yamato's armor, but the belt is thicker than Yamato's.


457mm.
http://en.wikipedia.org/wiki/Fuji_class_battleship

360-450mm.
http://homepage2.nifty.com/nishidah/e/stc0107.htm
http://www.warshipsww2.eu/lode.php?language=E&period=&idtrida=2061

I simmed it as 457mm.
http://www.navalism.org/index.php?topic=693.msg4412#msg4412

[Valles]

*nod* Well, now, that's interesting to know...

Either way, though, mods gave me the figure of fifteen inches when I was figuring out how thickly I could protect Cross Mirage.

[maddox]

Valles, when -Nverse year- did the moderators say 15" was about the maximum thickness of qualitative armorplate?

On the gun caliber.  380mm is the max for Nverse France at the moment (1917) , but won't stay there.
Unfortunatly with he other qualities wished for the French ships, 40Ktons is a limiting factor. Thats 4 years of build time- building maximal economical speed. Annoying for politicians that have their seats for 5 years.

[Valles]

About 1914, I believe, given that that's when I was laying CM down. Although, obviously, she ended up waiting four years while difficulties with those selfsame plates were worked out.