AHC: best 1940 BB

There is only so big the RN can go without significant investment in new drydocks at the fleet bases, so basically 106 ft is the effective maximum beam from what I remember.
 
There are quite a few simple improvements over OTL designs, which is nice in the way they would require less of a POD, but not as nice for the purpose of pushing the technology.
Let’s assume the troll Germany designs is an uparmored, 3x2 16 inch, 31-32 knots scharnhorst class with mixed diesel/steam propulsion. For starters, lets assumed it is lavish equipped with effective AA guns, and maybe followed by a few Spahkreuzer’s.
A pair of these could engage an R class with reasonable chance of not receiving critical damage.
How are the 29-30 knots British ships going to catch these. They can’t guard all the convoys themselves.
 
You can go to 18 inch although that implies quite a compromise on 45000 ton.
Here's a quick RN battleship design using the BL 18-inch Mark II guns designed in 1920 in 2 x 3-gun turrets. It's 800 x 106 ft at 45,000 tons standard. Armor and bunkerage are heavier than the KGV standard, and speed is increased to 29 kts at 150,000 shp.

Displacement:
43,019 t light; 45,539 t standard; 49,290 t normal; 52,291 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
(797.05 ft / 775.00 ft) x 106.00 ft x (35.00 / 36.75 ft)
(242.94 m / 236.22 m) x 32.31 m x (10.67 / 11.20 m)

Armament:
6 - 18.00" / 457 mm 45.0 cal guns - 3,320.01lbs / 1,505.93kg shells, 100 per gun
Breech loading guns in turret on barbette mounts, 1920 Model
2 x 3-gun mounts on centreline ends, evenly spread
16 - 5.25" / 133 mm 50.0 cal guns - 80.01lbs / 36.29kg shells, 400 per gun
Quick firing guns in deck and hoist mounts, 1935 Model
8 x Twin mounts on sides, evenly spread
4 raised mounts
64 - 1.57" / 40.0 mm 40.0 cal guns - 2.01lbs / 0.91kg shells, 2,000 per gun
Anti-air guns in deck mounts, 1923 Model
8 x 2 row octuple mounts on sides, evenly spread
4 raised mounts
Weight of broadside 21,329 lbs / 9,674 kg

Armour:
- Belts: Width (max) Length (avg) Height (avg)
Main: 16.0" / 406 mm 503.75 ft / 153.54 m 12.35 ft / 3.76 m
Ends: 3.00" / 76 mm 271.23 ft / 82.67 m 12.35 ft / 3.76 m
Upper: 3.00" / 76 mm 503.75 ft / 153.54 m 8.00 ft / 2.44 m
Main Belt covers 100 % of normal length

- Torpedo Bulkhead - Additional damage containing bulkheads:
2.00" / 51 mm 503.75 ft / 153.54 m 33.00 ft / 10.06 m
Beam between torpedo bulkheads 75.00 ft / 22.86 m

- Hull void:
1.50" / 38 mm 503.75 ft / 153.54 m 33.00 ft / 10.06 m

- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 18.0" / 457 mm 8.00" / 203 mm 18.0" / 457 mm
2nd: 2.50" / 64 mm 1.00" / 25 mm 2.50" / 64 mm
3rd: 1.00" / 25 mm 1.00" / 25 mm -

- Armoured deck - multiple decks:
For and Aft decks: 8.00" / 203 mm
Forecastle: 2.00" / 51 mm Quarter deck: 4.00" / 102 mm

- Conning towers: Forward 4.00" / 102 mm, Aft 4.00" / 102 mm

Machinery:
Oil fired boilers, steam turbines,
Geared drive, 4 shafts, 150,000 shp / 111,900 Kw = 29.05 kts
Range 12,000nm at 15.00 kts
Bunker at max displacement = 6,752 tons

Complement:
1,653 - 2,150

Cost:
£21.761 million / $87.042 million

Distribution of weights at normal displacement:
Armament: 3,633 tons, 7.4 %
- Guns: 3,633 tons, 7.4 %
Armour: 18,410 tons, 37.4 %
- Belts: 5,158 tons, 10.5 %
- Torpedo bulkhead: 1,230 tons, 2.5 %
- Void: 923 tons, 1.9 %
- Armament: 2,938 tons, 6.0 %
- Armour Deck: 7,930 tons, 16.1 %
- Conning Towers: 232 tons, 0.5 %
Machinery: 4,107 tons, 8.3 %
Hull, fittings & equipment: 16,119 tons, 32.7 %
Fuel, ammunition & stores: 6,271 tons, 12.7 %
Miscellaneous weights: 750 tons, 1.5 %
- On freeboard deck: 750 tons

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
77,657 lbs / 35,225 Kg = 26.6 x 18.0 " / 457 mm shells or 12.3 torpedoes
Stability (Unstable if below 1.00): 1.21
Metacentric height 7.8 ft / 2.4 m
Roll period: 16.0 seconds
Steadiness - As gun platform (Average = 50 %): 56 %
- Recoil effect (Restricted arc if above 1.00): 0.58
Seaboat quality (Average = 1.00): 1.12

Hull form characteristics:
Hull has rise forward of midbreak,
a normal bow and a cruiser stern
Block coefficient (normal/deep): 0.600 / 0.606
Length to Beam Ratio: 7.31 : 1
'Natural speed' for length: 27.84 kts
Power going to wave formation at top speed: 52 %
Trim (Max stability = 0, Max steadiness = 100): 50
Bow angle (Positive = bow angles forward): 25.00 degrees
Stern overhang: 8.00 ft / 2.44 m
Freeboard (% = length of deck as a percentage of waterline length):
Fore end, Aft end
- Forecastle: 20.00 %, 30.12 ft / 9.18 m, 26.00 ft / 7.92 m
- Forward deck: 30.00 %, 26.00 ft / 7.92 m, 26.00 ft / 7.92 m
- Aft deck: 35.00 %, 18.00 ft / 5.49 m, 18.00 ft / 5.49 m
- Quarter deck: 15.00 %, 18.00 ft / 5.49 m, 18.00 ft / 5.49 m
- Average freeboard: 22.33 ft / 6.81 m
Ship tends to be wet forward

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 86.6 %
- Above water (accommodation/working, high = better): 150.2 %
Waterplane Area: 60,083 Square feet or 5,582 Square metres
Displacement factor (Displacement / loading): 111 %
Structure weight / hull surface area: 208 lbs/sq ft or 1,014 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.97
- Longitudinal: 1.38
- Overall: 1.00
Adequate machinery, storage, compartmentation space
Excellent accommodation and workspace room
 
There are quite a few simple improvements over OTL designs, which is nice in the way they would require less of a POD, but not as nice for the purpose of pushing the technology.
Let’s assume the troll Germany designs is an uparmored, 3x2 16 inch, 31-32 knots scharnhorst class with mixed diesel/steam propulsion. For starters, lets assumed it is lavish equipped with effective AA guns, and maybe followed by a few Spahkreuzer’s.
A pair of these could engage an R class with reasonable chance of not receiving critical damage.
How are the 29-30 knots British ships going to catch these. They can’t guard all the convoys themselves.

The AA guns is hindsight speaking, and speaking in tongues... if the threat from aircraft is regarded as that high, then it is also known that it's extremely risky to operate without your own fighter cover. That understanding wasn't present in 1936, and wasn't actually justified on the technology of the day either. For Germany, a close-range encounter with destroyers or cruisers at night or in bad weather was the greater threat.

31-32 kts gives little advantage over a 29 kt opponent; it's not enough to reliably be able to run away, given engine conditions, damage and weather, as North Cape showed. So the historical speed of the KGVs would be deemed enough.

The super Scharnhorst is an interesting idea, but one-on-one it's outmatched by a Lion, and would probably have to retreat from a Nelson. More broadly, the answer to your question depends entirely on the British naval response to no LNT2 and German construction of super-battlecruisers, and the political consequences, which may or may not lead to a war at all. The basic outline of the naval response is a KGV class with 16" guns - essentially a Lion, potentially with Vanguards also depending on subsequent German construction, and additional scouting forces if it becomes clear that Germany is building a raiding fleet.
 
Here's a quick RN battleship design using the BL 18-inch Mark II guns designed in 1920 in 2 x 3-gun turrets. It's 800 x 106 ft at 45,000 tons standard. Armor and bunkerage are heavier than the KGV standard, and speed is increased to 29 kts at 150,000 shp.

Displacement:
43,019 t light; 45,539 t standard; 49,290 t normal; 52,291 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
(797.05 ft / 775.00 ft) x 106.00 ft x (35.00 / 36.75 ft)
(242.94 m / 236.22 m) x 32.31 m x (10.67 / 11.20 m)

Armament:
6 - 18.00" / 457 mm 45.0 cal guns - 3,320.01lbs / 1,505.93kg shells, 100 per gun
Breech loading guns in turret on barbette mounts, 1920 Model
2 x 3-gun mounts on centreline ends, evenly spread
16 - 5.25" / 133 mm 50.0 cal guns - 80.01lbs / 36.29kg shells, 400 per gun
Quick firing guns in deck and hoist mounts, 1935 Model
8 x Twin mounts on sides, evenly spread
4 raised mounts
64 - 1.57" / 40.0 mm 40.0 cal guns - 2.01lbs / 0.91kg shells, 2,000 per gun
Anti-air guns in deck mounts, 1923 Model
8 x 2 row octuple mounts on sides, evenly spread
4 raised mounts
Weight of broadside 21,329 lbs / 9,674 kg

Armour:
- Belts: Width (max) Length (avg) Height (avg)
Main: 16.0" / 406 mm 503.75 ft / 153.54 m 12.35 ft / 3.76 m
Ends: 3.00" / 76 mm 271.23 ft / 82.67 m 12.35 ft / 3.76 m
Upper: 3.00" / 76 mm 503.75 ft / 153.54 m 8.00 ft / 2.44 m
Main Belt covers 100 % of normal length

- Torpedo Bulkhead - Additional damage containing bulkheads:
2.00" / 51 mm 503.75 ft / 153.54 m 33.00 ft / 10.06 m
Beam between torpedo bulkheads 75.00 ft / 22.86 m

- Hull void:
1.50" / 38 mm 503.75 ft / 153.54 m 33.00 ft / 10.06 m

- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 18.0" / 457 mm 8.00" / 203 mm 18.0" / 457 mm
2nd: 2.50" / 64 mm 1.00" / 25 mm 2.50" / 64 mm
3rd: 1.00" / 25 mm 1.00" / 25 mm -

- Armoured deck - multiple decks:
For and Aft decks: 8.00" / 203 mm
Forecastle: 2.00" / 51 mm Quarter deck: 4.00" / 102 mm

- Conning towers: Forward 4.00" / 102 mm, Aft 4.00" / 102 mm

Machinery:
Oil fired boilers, steam turbines,
Geared drive, 4 shafts, 150,000 shp / 111,900 Kw = 29.05 kts
Range 12,000nm at 15.00 kts
Bunker at max displacement = 6,752 tons

Complement:
1,653 - 2,150

Cost:
£21.761 million / $87.042 million

Distribution of weights at normal displacement:
Armament: 3,633 tons, 7.4 %
- Guns: 3,633 tons, 7.4 %
Armour: 18,410 tons, 37.4 %
- Belts: 5,158 tons, 10.5 %
- Torpedo bulkhead: 1,230 tons, 2.5 %
- Void: 923 tons, 1.9 %
- Armament: 2,938 tons, 6.0 %
- Armour Deck: 7,930 tons, 16.1 %
- Conning Towers: 232 tons, 0.5 %
Machinery: 4,107 tons, 8.3 %
Hull, fittings & equipment: 16,119 tons, 32.7 %
Fuel, ammunition & stores: 6,271 tons, 12.7 %
Miscellaneous weights: 750 tons, 1.5 %
- On freeboard deck: 750 tons

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
77,657 lbs / 35,225 Kg = 26.6 x 18.0 " / 457 mm shells or 12.3 torpedoes
Stability (Unstable if below 1.00): 1.21
Metacentric height 7.8 ft / 2.4 m
Roll period: 16.0 seconds
Steadiness - As gun platform (Average = 50 %): 56 %
- Recoil effect (Restricted arc if above 1.00): 0.58
Seaboat quality (Average = 1.00): 1.12

Hull form characteristics:
Hull has rise forward of midbreak,
a normal bow and a cruiser stern
Block coefficient (normal/deep): 0.600 / 0.606
Length to Beam Ratio: 7.31 : 1
'Natural speed' for length: 27.84 kts
Power going to wave formation at top speed: 52 %
Trim (Max stability = 0, Max steadiness = 100): 50
Bow angle (Positive = bow angles forward): 25.00 degrees
Stern overhang: 8.00 ft / 2.44 m
Freeboard (% = length of deck as a percentage of waterline length):
Fore end, Aft end
- Forecastle: 20.00 %, 30.12 ft / 9.18 m, 26.00 ft / 7.92 m
- Forward deck: 30.00 %, 26.00 ft / 7.92 m, 26.00 ft / 7.92 m
- Aft deck: 35.00 %, 18.00 ft / 5.49 m, 18.00 ft / 5.49 m
- Quarter deck: 15.00 %, 18.00 ft / 5.49 m, 18.00 ft / 5.49 m
- Average freeboard: 22.33 ft / 6.81 m
Ship tends to be wet forward

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 86.6 %
- Above water (accommodation/working, high = better): 150.2 %
Waterplane Area: 60,083 Square feet or 5,582 Square metres
Displacement factor (Displacement / loading): 111 %
Structure weight / hull surface area: 208 lbs/sq ft or 1,014 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.97
- Longitudinal: 1.38
- Overall: 1.00
Adequate machinery, storage, compartmentation space
Excellent accommodation and workspace room
I’d say the 6 guns is a serious compronise.
In my German example they would need to compromise further with 3*2 16 inch because of a need for great range.
 
The AA guns is hindsight speaking, and speaking in tongues... if the threat from aircraft is regarded as that high, then it is also known that it's extremely risky to operate without your own fighter cover. That understanding wasn't present in 1936, and wasn't actually justified on the technology of the day either. For Germany, a close-range encounter with destroyers or cruisers at night or in bad weather was the greater threat.

31-32 kts gives little advantage over a 29 kt opponent; it's not enough to reliably be able to run away, given engine conditions, damage and weather, as North Cape showed. So the historical speed of the KGVs would be deemed enough.

The super Scharnhorst is an interesting idea, but one-on-one it's outmatched by a Lion, and would probably have to retreat from a Nelson. More broadly, the answer to your question depends entirely on the British naval response to no LNT2 and German construction of super-battlecruisers, and the political consequences, which may or may not lead to a war at all. The basic outline of the naval response is a KGV class with 16" guns - essentially a Lion, potentially with Vanguards also depending on subsequent German construction, and additional scouting forces if it becomes clear that Germany is building a raiding fleet.
I would not disagree that the Lion would be better of one-on-one than the “super scharnhorst” but it is a serious disadvantage not to keep pace. The super scharnhorst Can disengage against a lion, because there are other convoys.
North Cape is the example available, but was won because of developments in radar allowing DOY to sneak in close.
I agree the AA guns I propose is hindsight/or at least foresight not predominant iotl, but that is allowed in this thread.
I want to see what could be done first and foremost.
 
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I have been fascinated by battleship designs since joining this forum, and it is an interesting “technology” as it basically stopped during WW2.
The challenge is to make the best possible 45000 ton ship in 1940 using methods and technologies from either country. Developed or not iotl, but at least within reach with a 1930’ish pod.

Funny, I was just mentioning Alsace on another board this morning, but I think if you go to 45,000 tons standard, the third version might be hard to beat:

https://stefsap.wordpress.com/2016/03/05/mn-alsace-gascogne-clemenceau-battleships-add-on/

12 x 15in/380mm on 45,000 tons. If that ship had been built, we might be having debates on which ship was better Alsace or Iowa instead of Iowa and Yamato.

One of the considerations leading to the USN's Montana was a 1940 design with 12 x 16in/45 on 44,500 tons, BB65A

EarlyDesigns_zps2504a41a.gif


EarlyDesignsS_zps9257add1.gif


So a Montana precursor could easily be a contender. The 16in/45 with the superheavy shell was actually a better deck penetration round than the 16in/50 with the same shell....

Great topic, interested to see more replies.

Edit-My mistake. Now that I'm close to my sources, BB65-A would have had the 16in/50, not the /45.

Regards,
 
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