WesWorld

A proposal for a new class of US battleships. Too large for the Panama canal, but it will fit through the Mexican canal.


USS Montana, United States Battleship laid down 1937

Displacement:
54,565 t light; 58,064 t standard; 62,304 t normal; 65,696 t full load

Dimensions: Length overall / water x beam x draught
910.17 ft / 880.00 ft x 120.00 ft x 35.00 ft (normal load)
277.42 m / 268.22 m x 36.58 m x 10.67 m

Armament:
12 - 16.00" / 406 mm guns (4x3 guns), 2,700.00lbs / 1,224.70kg shells, 1937 Model
Breech loading guns in turrets (on barbettes)
on centreline ends, evenly spread, 2 raised mounts - superfiring
20 - 5.00" / 127 mm guns (10x2 guns), 55.18lbs / 25.03kg shells, 1937 Model
Dual purpose guns in deck mounts with hoists
on side, evenly spread, 4 raised mounts
56 - 1.10" / 27.9 mm guns (14x4 guns), 0.67lbs / 0.30kg shells, 1937 Model
Anti-aircraft guns in deck mounts
on side, evenly spread, 6 raised mounts
16 - 0.50" / 12.7 mm guns (8x2 guns), 0.06lbs / 0.03kg shells, 1937 Model
Machine guns in deck mounts
on side, evenly spread, all raised mounts
Weight of broadside 33,542 lbs / 15,214 kg
Shells per gun, main battery: 120

Armour:
- Belts: Width (max) Length (avg) Height (avg)
Main: 17.0" / 432 mm 554.40 ft / 168.98 m 12.70 ft / 3.87 m
Ends: Unarmoured
Upper: 3.00" / 76 mm 554.40 ft / 168.98 m 5.30 ft / 1.62 m
Main Belt covers 97 % of normal length

- Torpedo Bulkhead:
3.00" / 76 mm 554.40 ft / 168.98 m 32.93 ft / 10.04 m

- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 22.0" / 559 mm 9.00" / 229 mm 16.0" / 406 mm
2nd: 2.00" / 51 mm 1.00" / 25 mm 2.00" / 51 mm

- Armour deck: 7.00" / 178 mm, Conning tower: 18.00" / 457 mm

Machinery:
Oil fired boilers, steam turbines,
Electric motors, 4 shafts, 127,118 shp / 94,830 Kw = 28.00 kts
Range 12,000nm at 15.00 kts
Bunker at max displacement = 7,632 tons

Complement:
1,971 - 2,563

Cost:
£27.921 million / $111.682 million

Distribution of weights at normal displacement:
Armament: 3,233 tons, 5.2 %
Armour: 23,310 tons, 37.4 %
- Belts: 5,573 tons, 8.9 %
- Torpedo bulkhead: 2,026 tons, 3.3 %
- Armament: 4,777 tons, 7.7 %
- Armour Deck: 10,325 tons, 16.6 %
- Conning Tower: 609 tons, 1.0 %
Machinery: 3,523 tons, 5.7 %
Hull, fittings & equipment: 24,108 tons, 38.7 %
Fuel, ammunition & stores: 7,739 tons, 12.4 %
Miscellaneous weights: 390 tons, 0.6 %

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
89,709 lbs / 40,692 Kg = 43.8 x 16.0 " / 406 mm shells or 16.8 torpedoes
Stability (Unstable if below 1.00): 1.10
Metacentric height 7.9 ft / 2.4 m
Roll period: 18.0 seconds
Steadiness - As gun platform (Average = 50 %): 60 %
- Recoil effect (Restricted arc if above 1.00): 0.62
Seaboat quality (Average = 1.00): 1.07

Hull form characteristics:
Hull has a flush deck
and transom stern
Block coefficient: 0.590
Length to Beam Ratio: 7.33 : 1
'Natural speed' for length: 34.37 kts
Power going to wave formation at top speed: 46 %
Trim (Max stability = 0, Max steadiness = 100): 56
Bow angle (Positive = bow angles forward): 40.00 degrees
Stern overhang: 5.00 ft / 1.52 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 30.00 ft / 9.14 m
- Forecastle (22 %): 18.00 ft / 5.49 m
- Mid (50 %): 18.00 ft / 5.49 m
- Quarterdeck (15 %): 18.00 ft / 5.49 m
- Stern: 18.00 ft / 5.49 m
- Average freeboard: 19.06 ft / 5.81 m
Ship tends to be wet forward

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 72.0 %
- Above water (accommodation/working, high = better): 138.7 %
Waterplane Area: 79,729 Square feet or 7,407 Square metres
Displacement factor (Displacement / loading): 110 %
Structure weight / hull surface area: 237 lbs/sq ft or 1,157 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.99
- Longitudinal: 1.00
- Overall: 1.00
Hull space for machinery, storage, compartmentation is excellent
Room for accommodation and workspaces is excellent

100 tons for aircraft
50 tons for radar
240 tons for growth

Main belt armor is composed of a 3" decapping plate (carried to main deck height as upper belt armor), backed by a 14" main belt.

Yay! The armor on that beast is quite compelling...

I was just about to post one of my own. Much smaller, of course.

Quoted

USS Montana, United States Fast Battleship laid down 1936

Displacement:
37,998 t light; 40,564 t standard; 44,838 t normal; 48,257 t full load

Dimensions: Length overall / water x beam x draught
800.00 ft / 800.00 ft x 104.00 ft x 32.00 ft (normal load)
243.84 m / 243.84 m x 31.70 m x 9.75 m

Armament:
9 - 16.00" / 406 mm guns (3x3 guns), 2,048.00lbs / 928.96kg shells, 1936 Model
Breech loading guns in turrets (on barbettes)
on centreline ends, majority forward, 1 raised mount - superfiring
20 - 5.00" / 127 mm guns (10x2 guns), 62.50lbs / 28.35kg shells, 1936 Model
Dual purpose guns in deck mounts with hoists
on side, all amidships, 4 raised mounts - superfiring
30 - 1.57" / 40.0 mm guns (10x3 guns), 1.95lbs / 0.89kg shells, 1936 Model
Anti-aircraft guns in deck mounts with hoists
on side, evenly spread, all raised mounts
20 - 0.79" / 20.0 mm guns (10x2 guns), 0.24lbs / 0.11kg shells, 1936 Model
Anti-aircraft guns in deck mounts
on side, evenly spread
Weight of broadside 19,745 lbs / 8,956 kg
Shells per gun, main battery: 150

Armour:
- Belts: Width (max) Length (avg) Height (avg)
Main: 14.0" / 356 mm 520.00 ft / 158.50 m 12.24 ft / 3.73 m
Ends: Unarmoured
Main Belt covers 100 % of normal length

- Torpedo Bulkhead:
3.00" / 76 mm 520.00 ft / 158.50 m 29.37 ft / 8.95 m

- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 15.0" / 381 mm 11.0" / 279 mm 13.0" / 330 mm

- Armour deck: 5.00" / 127 mm, Conning tower: 15.00" / 381 mm

Machinery:
Oil fired boilers, steam turbines,
Geared drive, 4 shafts, 92,678 shp / 69,137 Kw = 27.00 kts
Range 15,000nm at 15.00 kts
Bunker at max displacement = 7,692 tons

Complement:
1,539 - 2,002

Cost:
£19.864 million / $79.455 million

Distribution of weights at normal displacement:
Armament: 2,468 tons, 5.5 %
Armour: 15,059 tons, 33.6 %
- Belts: 3,820 tons, 8.5 %
- Torpedo bulkhead: 1,695 tons, 3.8 %
- Armament: 3,329 tons, 7.4 %
- Armour Deck: 5,807 tons, 13.0 %
- Conning Tower: 408 tons, 0.9 %
Machinery: 2,600 tons, 5.8 %
Hull, fittings & equipment: 17,670 tons, 39.4 %
Fuel, ammunition & stores: 6,840 tons, 15.3 %
Miscellaneous weights: 200 tons, 0.4 %

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
71,013 lbs / 32,211 Kg = 34.7 x 16.0 " / 406 mm shells or 12.1 torpedoes
Stability (Unstable if below 1.00): 1.11
Metacentric height 6.5 ft / 2.0 m
Roll period: 17.2 seconds
Steadiness - As gun platform (Average = 50 %): 70 %
- Recoil effect (Restricted arc if above 1.00): 0.78
Seaboat quality (Average = 1.00): 1.40

Hull form characteristics:
Hull has a flush deck
and transom stern
Block coefficient: 0.589
Length to Beam Ratio: 7.69 : 1
'Natural speed' for length: 32.64 kts
Power going to wave formation at top speed: 46 %
Trim (Max stability = 0, Max steadiness = 100): 50
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: 33.00 ft / 10.06 m
- Forecastle (20 %): 22.00 ft / 6.71 m
- Mid (50 %): 22.00 ft / 6.71 m
- Quarterdeck (15 %): 22.00 ft / 6.71 m
- Stern: 22.00 ft / 6.71 m
- Average freeboard: 22.88 ft / 6.97 m

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 77.4 %
- Above water (accommodation/working, high = better): 170.9 %
Waterplane Area: 62,783 Square feet or 5,833 Square metres
Displacement factor (Displacement / loading): 112 %
Structure weight / hull surface area: 206 lbs/sq ft or 1,007 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.97
- Longitudinal: 1.27
- 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

Then there's a possible rebuild for the Lexingtons:

USS Lexington, United States Battlecruiser laid down 1919 (Engine 1936)

Displacement:
42,607 t light; 44,843 t standard; 48,061 t normal; 50,635 t full load

Dimensions: Length overall / water x beam x draught
873.11 ft / 850.00 ft x 100.00 ft (Bulges 118.00 ft) x 31.00 ft (normal load)
266.12 m / 259.08 m x 30.48 m (Bulges 35.97 m) x 9.45 m

Armament:
8 - 16.00" / 406 mm guns (4x2 guns), 2,250.00lbs / 1,020.58kg shells, 1936 Model
Breech loading guns in turrets (on barbettes)
on centreline ends, evenly spread, 2 raised mounts - superfiring
16 - 5.00" / 127 mm guns (8x2 guns), 55.18lbs / 25.03kg shells, 1938 Model
Dual purpose guns in deck mounts with hoists
on side, all amidships, 4 raised mounts - superfiring
56 - 1.10" / 27.9 mm guns (10 mounts), 0.67lbs / 0.30kg shells, 1938 Model
Anti-aircraft guns in deck mounts
on side, evenly spread, 24 raised guns
12 - 0.50" / 12.7 mm guns in single mounts, 0.06lbs / 0.03kg shells, 1919 Model
Machine guns in deck mounts
on side, evenly spread, all raised mounts
Weight of broadside 18,921 lbs / 8,582 kg
Shells per gun, main battery: 120

Armour:
- Belts: Width (max) Length (avg) Height (avg)
Main: 12.0" / 305 mm 624.00 ft / 190.20 m 12.00 ft / 3.66 m
Ends: Unarmoured
Main Belt covers 113 % of normal length

- Torpedo Bulkhead and Bulges:
3.00" / 76 mm 550.00 ft / 167.64 m 28.74 ft / 8.76 m

- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 13.0" / 330 mm 6.00" / 152 mm 12.0" / 305 mm
2nd: 2.50" / 64 mm 2.50" / 64 mm 2.50" / 64 mm
3rd: 1.00" / 25 mm - -
4th: 0.50" / 13 mm - -

- Armour deck: 4.50" / 114 mm, Conning tower: 12.00" / 305 mm

Machinery:
Oil fired boilers, steam turbines,
Electric motors, 4 shafts, 219,703 shp / 163,899 Kw = 32.50 kts
Range 10,000nm at 15.00 kts
Bunker at max displacement = 5,791 tons

Complement:
1,622 - 2,109

Cost:
£9.128 million / $36.511 million

Distribution of weights at normal displacement:
Armament: 2,178 tons, 4.5 %
Armour: 14,315 tons, 29.8 %
- Belts: 3,724 tons, 7.7 %
- Torpedo bulkhead: 1,755 tons, 3.7 %
- Armament: 3,598 tons, 7.5 %
- Armour Deck: 4,897 tons, 10.2 %
- Conning Tower: 342 tons, 0.7 %
Machinery: 6,165 tons, 12.8 %
Hull, fittings & equipment: 19,699 tons, 41.0 %
Fuel, ammunition & stores: 5,454 tons, 11.3 %
Miscellaneous weights: 250 tons, 0.5 %

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
64,450 lbs / 29,234 Kg = 31.5 x 16.0 " / 406 mm shells or 10.4 torpedoes
Stability (Unstable if below 1.00): 1.18
Metacentric height 6.8 ft / 2.1 m
Roll period: 19.0 seconds
Steadiness - As gun platform (Average = 50 %): 52 %
- Recoil effect (Restricted arc if above 1.00): 0.52
Seaboat quality (Average = 1.00): 1.04

Hull form characteristics:
Hull has low quarterdeck
Block coefficient: 0.541
Length to Beam Ratio: 7.20 : 1
'Natural speed' for length: 29.15 kts
Power going to wave formation at top speed: 53 %
Trim (Max stability = 0, Max steadiness = 100): 50
Bow angle (Positive = bow angles forward): 34.20 degrees
Stern overhang: 0.00 ft / 0.00 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 34.00 ft / 10.36 m
- Forecastle (20 %): 27.70 ft / 8.44 m
- Mid (50 %): 25.70 ft / 7.83 m
- Quarterdeck (18 %): 18.70 ft / 5.70 m (25.70 ft / 7.83 m before break)
- Stern: 18.70 ft / 5.70 m
- Average freeboard: 25.60 ft / 7.80 m

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 96.6 %
- Above water (accommodation/working, high = better): 180.9 %
Waterplane Area: 58,823 Square feet or 5,465 Square metres
Displacement factor (Displacement / loading): 108 %
Structure weight / hull surface area: 219 lbs/sq ft or 1,070 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.98
- Longitudinal: 1.19
- Overall: 1.00
Hull space for machinery, storage, compartmentation is adequate
Room for accommodation and workspaces is excellent

100 tons reserved for aircraft
50 tons reserved for radar
100 tons reserved for growth

The Lexingtons are wuv! I just adore their looks... real classy ships.

And then there's the 18" Montana:

USS Montana, United States Battleship laid down 1937

Displacement:
53,215 t light; 56,420 t standard; 61,859 t normal; 66,210 t full load

Dimensions: Length overall / water x beam x draught
908.17 ft / 880.00 ft x 105.00 ft (Bulges 120.00 ft) x 34.75 ft (normal load)
276.81 m / 268.22 m x 32.00 m (Bulges 36.58 m) x 10.59 m

Armament:
8 - 18.00" / 457 mm guns (4x2 guns), 3,850.00lbs / 1,746.33kg shells, 1937 Model
Breech loading guns in turrets (on barbettes)
on centreline ends, evenly spread, 2 raised mounts - superfiring
20 - 5.00" / 127 mm guns (10x2 guns), 55.18lbs / 25.03kg shells, 1937 Model
Dual purpose guns in deck mounts with hoists
on side, evenly spread, 4 raised mounts
56 - 1.10" / 27.9 mm guns (14x4 guns), 0.67lbs / 0.30kg shells, 1937 Model
Anti-aircraft guns in deck mounts
on side, evenly spread, 6 raised mounts
16 - 0.50" / 12.7 mm guns (8x2 guns), 0.06lbs / 0.03kg shells, 1937 Model
Machine guns in deck mounts
on side, evenly spread, all raised mounts
Weight of broadside 31,942 lbs / 14,489 kg
Shells per gun, main battery: 110

Armour:
- Belts: Width (max) Length (avg) Height (avg)
Main: 17.0" / 432 mm 572.00 ft / 174.35 m 12.30 ft / 3.75 m
Ends: Unarmoured
Upper: 3.00" / 76 mm 572.00 ft / 174.35 m 6.45 ft / 1.97 m
Main Belt covers 100 % of normal length

- Torpedo Bulkhead and Bulges:
3.00" / 76 mm 572.00 ft / 174.35 m 32.86 ft / 10.02 m

- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 24.0" / 610 mm 9.00" / 229 mm 16.0" / 406 mm
2nd: 2.00" / 51 mm 1.00" / 25 mm 2.00" / 51 mm

- Armour deck: 7.50" / 191 mm, Conning tower: 18.00" / 457 mm

Machinery:
Oil fired boilers, steam turbines,
Electric motors, 4 shafts, 143,504 shp / 107,054 Kw = 28.00 kts
Range 15,000nm at 15.00 kts
Bunker at max displacement = 9,791 tons

Complement:
1,960 - 2,549

Cost:
£27.295 million / $109.180 million

Distribution of weights at normal displacement:
Armament: 3,077 tons, 5.0 %
Armour: 22,428 tons, 36.3 %
- Belts: 5,553 tons, 9.0 %
- Torpedo bulkhead: 2,086 tons, 3.4 %
- Armament: 4,893 tons, 7.9 %
- Armour Deck: 9,289 tons, 15.0 %
- Conning Tower: 607 tons, 1.0 %
Machinery: 3,977 tons, 6.4 %
Hull, fittings & equipment: 23,382 tons, 37.8 %
Fuel, ammunition & stores: 8,644 tons, 14.0 %
Miscellaneous weights: 350 tons, 0.6 %

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
86,991 lbs / 39,458 Kg = 29.8 x 18.0 " / 457 mm shells or 16.5 torpedoes
Stability (Unstable if below 1.00): 1.08
Metacentric height 6.2 ft / 1.9 m
Roll period: 20.2 seconds
Steadiness - As gun platform (Average = 50 %): 70 %
- Recoil effect (Restricted arc if above 1.00): 0.75
Seaboat quality (Average = 1.00): 1.20

Hull form characteristics:
Hull has a flush deck
Block coefficient: 0.590
Length to Beam Ratio: 7.33 : 1
'Natural speed' for length: 29.66 kts
Power going to wave formation at top speed: 46 %
Trim (Max stability = 0, Max steadiness = 100): 58
Bow angle (Positive = bow angles forward): 40.00 degrees
Stern overhang: 3.00 ft / 0.91 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 30.00 ft / 9.14 m
- Forecastle (20 %): 20.75 ft / 6.32 m
- Mid (40 %): 20.75 ft / 6.32 m
- Quarterdeck (15 %): 20.75 ft / 6.32 m
- Stern: 20.75 ft / 6.32 m
- Average freeboard: 21.49 ft / 6.55 m
Ship tends to be wet forward

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 74.7 %
- Above water (accommodation/working, high = better): 135.0 %
Waterplane Area: 66,951 Square feet or 6,220 Square metres
Displacement factor (Displacement / loading): 112 %
Structure weight / hull surface area: 239 lbs/sq ft or 1,167 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.99
- Longitudinal: 1.05
- 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

100 tons for aircraft
50 tons for radar
200 tons for growth

Main belt armor is composed of a 3" decapping plate (carried to main deck height as upper belt armor), backed by a 14" main belt.

US 16" superheavy shell!

Prodigious broadside weight.

Powerfully armored. Enormous survivability.

Adequate speed for the post-Cleito Treaty world.

What's not to like?

Although, why bulge the 18" version and not the 16" version? You could add even more armor with the extra hull strength!

Well, looks like the Montana's are a couple years earlier than in OTL. I wanna see a showdown between these giants and the Japanese ones. Wonder what the response of the rest of the world is going to be. (Poland and Romania furiously began planning a 70000 ton ship for Poland in response jk). Perhaps the real question is how many BB's are the Americans planning for?

Alaskas now?

Quoted

Originally posted by TheCanadian
Well, looks like the Montana's are a couple years earlier than in OTL. I wanna see a showdown between these giants and the Japanese ones. Wonder what the response of the rest of the world is going to be.

Wait and see!

Who is going to produce 22" plates and how?

I also think her armour suit is excessive. You simply don´t need that much armour against 15", 16" or even 18" shells. Then - You can´t armour all of your ship anyway so you will receive damage and you can still be soft-killed.

Quoted

Originally posted by HoOmAn
Who is going to produce 22" plates and how?

I also think her armour suit is excessive. You simply don´t need that much armour against 15", 16" or even 18" shells. Then - You can´t armour all of your ship anyway so you will receive damage and you can still be soft-killed.

Historically, Japan produced 26" armor plate for the turret fronts on the Yamatos, see the testing results here: http://www.navweaps.com/index_tech/tech-040.htm So I doubt that would be a serious problem.


The rest of the armor scheme is based on the Standards, though the 13.5" armor is upped to 14" and a 3" decapping plate added. The belt extends farther fore and aft than is necessary to cover the magazines and engines to ensure that any end damage is not enough to threaten the survival of the ship.

Quoted

Originally posted by AdmKuznetsov
US 16" superheavy shell!

Prodigious broadside weight.

Powerfully armored. Enormous survivability.

Adequate speed for the post-Cleito Treaty world.

What's not to like?

Although, why bulge the 18" version and not the 16" version? You could add even more armor with the extra hull strength!

The 18" version is a slightly later iteration of the design, I haven't yet gone back and done a 16" version of it.

Bulges are really just a cheat in SS to reduce the weight of armour. In real life, the extra deck space would be more useful, in addition to the extra internal space. Bulges aren't as good for torpedo protection or hydrodynamics as proper hull, but SS doesn't reflect this.

22" plates are possible to make, but it'll be homogenous armour. The 18" face plates on the USN BBs might make it seem like they have masses of turret protection, but the 12.75" plates on KGV actually offer more protection. Of course, the turret face is a pretty small target area as well...

Quoted

Of course, the turret face is a pretty small target area as well...

but you can point it at the enemy...

Cheers,

Indeed.

I just guess the enemy is more scared of what is lurking out off those faceplates..... ;o)

Is it what lurks or what what lurks spits that is so scary?

I'd say 3,850 lbs shells would be considered scary.

Quoted

Main belt armor is composed of a 3" decapping plate (carried to main deck height as upper belt armor), backed by a 14" main belt.

So if I read that correctly, the bottom end of your main belt is at the waterline...

Is there much difference in the design if you were to stick to a 14" main belt and change the upper belt's height to 18 feet? This is the way I would sim it.

Quoted

I wanna see a showdown between these giants and the Japanese ones.

Well, it seems that a few are rather eager to see me build Yamatos, eventhough I planned to build a significant number of carriers and submarines instead...
... guess I'll have to satisfy their need for a Montana-Yamato confrontation and build a few Yamatos.

Quoted

Originally posted by Rooijen10

Quoted

Main belt armor is composed of a 3" decapping plate (carried to main deck height as upper belt armor), backed by a 14" main belt.

So if I read that correctly, the bottom end of your main belt is at the waterline...

No I think he said the decaping plate is at the waterline, its part of the main belt scheme.

I haven't looked closely at these but a couple of items.

Draft: May be irrelevant for the US, but 34 feet is about maximum for Suez in this era. For that matter for the Huston and Beumont-Port Arthur canals ... though those latter two are not likely to factor in

First, the main belt is quite short. These are long ships designed to fight opponents with large diameter shells. From the bits I've read, bigger shells can dive deeper before turning- or some such. While you've mentioned it's like the standards...it's not. The Nevada had an nearly 18' high belt, with slightly over 8 feet underwater, and no upper armor.

On turret faceplates- I read recently that on at least one US BB, they simply riveted a face hardened plate onto the homogenous turret face, creating the thick front.

Deck. I suppose it depends on if the thickness is for shells or bombs. Bombs it seems a little early- though Yamato went nuts with deck armor- but with shells there comes a point where an extra 1/2" is only buying 1,000 yards and you're already immune out past 30,000 depending on foe.

The bulges I saw were 15' wide. Which means a shell landing 7.5' short of your ship can enter the bulge, and dive through it, or more easily have a bomb enter the bulge and explode, etc and when it's wrecked there is a very large area compromised.

I do use external bulges, but I'm trying to keep them small to limit negatives while still reaping some positives. I think 15feet is moving into negatives.

I noted a wet forward on one of the ships.