Weekly US and Japan ship design challenge

[bklooste]

I kind of enjoyed the last 2 threads so i thought i would start a thread to discuss some alternative scenario designs.

2 ships each week one allied and one Japanese.

The best design will be noted. Bonus points for designs based on real proposals ,cheap / cost effective designs or ones which have springgsharp data ( if they are a bit questionable). The goal is not to rort the system but to build good designs with our 20/20 hind sight . The best option may be not to build it or to build more of an existing class.

Last week we talked about a 6-8K CL design for Japan from the Katori onwards and i think Terminus proposal was best - build no CL.

This week i will cover some Capital ships.


Japan gets 70% allowance from the Washington Naval treaty so has built the Kaga and Tosa.

US:
Rumours are around that Japan has allocated resources for up to 8 Battleships in 37-42. Japan pulled out of the Naval treaty in 35 and unless it joins you can build anything in 38. 4 South Dakotas have just been layed down and the escalator treaty is in effect. What does the US build / do congress is sympathetic to increasing the budget to address the deficient battle line ?

Japan:
The Kaga and Otari are in the line. Japan needs some BC / fast battleships and the Yamatos have been delayed. With 60K-90K tons what does Japan build ? Japan has seen some Blue prints from the South Dakotas . Options:
- Do you build the BC64 / SUper cruiser ?
- Do you refit some early BBs and recycle the turrets for a cheap new BB
- Do you create a new gun ?
- Do you build the proposed 18" gun BC ?

[DuckofTindalos]

Build all 4 South Dakotas, with 16-inch guns per the escalation clause. Move up the Iowas.

For the Japs, drop the Yamatos. Refit the Ise, Hyuga, Fuso and Yamashiro by removing two turrets from each and upgrading the powerplant to allow 28 knots. Assign the turrets to a new, fast BB design, with 2 ships. Build a couple of B-64s with 31cm guns, if nothing else than to make the US waste money on the Alaskas.

Drop all other capital ship building.

[bsq]

Weren't the South Dakotas laid down in 39/40 (not 38)?  Something to do with the CNO not liking the North Carolina design... So if they were laid down in 38, they would need to be repeat NC's.  And if your worry was matching Japanese construction, wouldn't the Admirals favour something more akin to the Montana's instead of the Iowa's - certainly designs with 12 x 16" were looked at when designing the follow on from the South Dakota's.

Does this extend to RN ships as well?  It seems unlikely that their lordships would be happy over the Japanese getting the 70% and that this would be used to fuel the argument to get the Lion's built.

[Iridium]

What happened to Akagi and Tosa in this scenario? Do we assume Tosa's hull was damaged during the earthquake or can both be used in their fast BB/BC configuration?

Dur, just noticed you mentioned they've been built as originally designed. Hmm...

I always did like the 18" BC designs, if one was of the configuration of something like 3 x 2 18" guns, 8 x 2 3.9" guns, ~40,000 tons, 34 Kts...etc

It would make for a decent CV escort and seems on par with Japanese thought on outmaneuvering an opponent to defeat them.

[Shark7]

Hmm, I'll look into this and see what I can come up with. I love a challenge. [;)]

[Shark7]

OK, for the Japan fast BB design I came up with this (done in SpringSharp 2.2). I went with a design more capable of being a carrier escort, high speed with good AAA:

Mino, Japan Battleship laid down 1938

Displacement:
33,666 t light; 35,417 t standard; 38,272 t normal; 40,555 t full load

Dimensions: Length overall / water x beam x draught
761.42 ft / 738.19 ft x 101.71 ft (Bulges 108.27 ft) x 27.89 ft (normal load)
232.08 m / 225.00 m x 31.00 m (Bulges 33.00 m) x 8.50 m

Armament:
9 - 14.17" / 360 mm guns (3x3 guns), 1,423.57lbs / 645.72kg shells, 1938 Model
Breech loading guns in turrets (on barbettes)
on centreline ends, majority forward, 1 raised mount - superfiring
20 - 3.94" / 100 mm guns (8 mounts), 30.51lbs / 13.84kg shells, 1938 Model
Dual purpose guns in deck mounts
on side, all amidships
48 - 0.98" / 25.0 mm guns (16x3 guns), 0.49lbs / 0.22kg shells, 1938 Model
Anti-aircraft guns in deck mounts
on side, all amidships
24 - 0.98" / 25.0 mm guns (8x3 guns), 0.49lbs / 0.22kg shells, 1938 Model
Anti-aircraft guns in deck mounts
on side, evenly spread
16 - 0.52" / 13.2 mm guns (8x2 guns), 0.07lbs / 0.03kg shells, 1938 Model
Machine guns in deck mounts
on centreline ends, evenly spread
Weight of broadside 13,459 lbs / 6,105 kg
Shells per gun, main battery: 130
8 - 24.0" / 610 mm above water torpedoes

Armour:
- Belts: Width (max) Length (avg) Height (avg)
Main: 11.8" / 300 mm 479.82 ft / 146.25 m 12.11 ft / 3.69 m
Ends: 2.99" / 76 mm 258.33 ft / 78.74 m 12.11 ft / 3.69 m
Upper: 4.92" / 125 mm 479.82 ft / 146.25 m 8.01 ft / 2.44 m
Main Belt covers 100 % of normal length

- Torpedo Bulkhead and Bulges:
2.13" / 54 mm 479.82 ft / 146.25 m 26.77 ft / 8.16 m

- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 12.8" / 325 mm 12.8" / 325 mm 12.8" / 325 mm
2nd: 0.98" / 25 mm 0.98" / 25 mm -

- Armour deck: 3.94" / 100 mm, Conning tower: 12.80" / 325 mm

Machinery:
Oil fired boilers, steam turbines,
Geared drive, 4 shafts, 147,600 shp / 110,110 Kw = 31.00 kts
Range 11,000nm at 15.00 kts
Bunker at max displacement = 5,138 tons

Complement:
1,367 - 1,778

Cost:
£17.795 million / $71.181 million

Distribution of weights at normal displacement:
Armament: 1,682 tons, 4.4 %
Armour: 12,716 tons, 33.2 %
- Belts: 4,124 tons, 10.8 %
- Torpedo bulkhead: 1,010 tons, 2.6 %
- Armament: 3,097 tons, 8.1 %
- Armour Deck: 4,172 tons, 10.9 %
- Conning Tower: 313 tons, 0.8 %
Machinery: 4,042 tons, 10.6 %
Hull, fittings & equipment: 14,976 tons, 39.1 %
Fuel, ammunition & stores: 4,606 tons, 12.0 %
Miscellaneous weights: 250 tons, 0.7 %

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
57,657 lbs / 26,153 Kg = 40.5 x 14.2 " / 360 mm shells or 9.4 torpedoes
Stability (Unstable if below 1.00): 1.11
Metacentric height 6.3 ft / 1.9 m
Roll period: 18.1 seconds
Steadiness - As gun platform (Average = 50 %): 54 %
- Recoil effect (Restricted arc if above 1.00): 0.45
Seaboat quality (Average = 1.00): 0.89

Hull form characteristics:
Hull has a flush deck
and transom stern
Block coefficient: 0.601
Length to Beam Ratio: 6.82 : 1
'Natural speed' for length: 31.64 kts
Power going to wave formation at top speed: 57 %
Trim (Max stability = 0, Max steadiness = 100): 60
Bow angle (Positive = bow angles forward): 30.00 degrees
Stern overhang: 6.56 ft / 2.00 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 28.87 ft / 8.80 m
- Forecastle (18 %): 26.25 ft / 8.00 m
- Mid (50 %): 22.97 ft / 7.00 m
- Quarterdeck (18 %): 19.69 ft / 6.00 m
- Stern: 18.37 ft / 5.60 m
- Average freeboard: 23.03 ft / 7.02 m
Ship tends to be wet forward

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 86.1 %
- Above water (accommodation/working, high = better): 165.7 %
Waterplane Area: 57,284 Square feet or 5,322 Square metres
Displacement factor (Displacement / loading): 111 %
Structure weight / hull surface area: 192 lbs/sq ft or 940 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.97
- Longitudinal: 1.24
- Overall: 1.00
Hull space for machinery, storage, compartmentation is adequate
Room for accommodation and workspaces is excellent
Poor seaboat, wet and uncomfortable, reduced performance in heavy weather

[stuman]

What is SpringSharp 2.2 ?

[Shark7]

Springsharp is a programme that allows you to design warships for simulation purposes.

You can read up on it better than I can explain it, website is here: http://www.springsharp.com/

[JuanG]

A little comment on springsharp designs;

I suggest you adopt the same guidelines as on NavWeaps for designs, meaning that seakeeping and stability should both be atleast 1.1 or more.

Apart from that (Seakeeping of 0.89!) theres two things I'd point out on your design.
1) Inadequate deck protection for a 35,000ton ship, especially a CV escort. Something like 140+mm would be nice.
2) Old style armour scheme with end and upper belt - any reason for this choice instead of a longer/deeper main belt and the associated weight savings?

Also, note the Japanese 36cm was actually 35.6cm (14in).


Here is my own suggestion; a 6 x 16 Renown-Style BC, with superfiring 6.1in as in Yamato, and sizeable secondary 3.9in battery.

Dewa, Japan Battlecruiser laid down 1938

Displacement:
34,783 t light; 36,833 t standard; 39,500 t normal; 41,634 t full load

Dimensions: Length overall / water x beam x draught
836.61 ft / 836.61 ft x 91.86 ft (Bulges 101.71 ft) x 32.81 ft (normal load)
255.00 m / 255.00 m x 28.00 m (Bulges 31.00 m) x 10.00 m

Armament:
6 - 16.14" / 410 mm guns (3x2 guns), 2,248.72lbs / 1,020.00kg shells, 1938 Model
Breech loading guns in turrets (on barbettes)
on centreline ends, majority forward, 1 raised mount - superfiring
6 - 6.10" / 155 mm guns (2x3 guns), 123.17lbs / 55.87kg shells, 1938 Model
Dual purpose guns in turrets (on barbettes)
on centreline ends, evenly spread, all raised mounts
20 - 3.94" / 100 mm guns (10x2 guns), 28.66lbs / 13.00kg shells, 1938 Model
Dual purpose guns in deck mounts with hoists
on side, all amidships, 4 raised mounts - superfiring
36 - 0.98" / 25.0 mm guns (12x3 guns), 0.48lbs / 0.22kg shells, 1938 Model
Anti-aircraft guns in deck mounts
on side, evenly spread, 4 raised mounts
16 - 0.98" / 25.0 mm guns (8x2 guns), 0.48lbs / 0.22kg shells, 1938 Model
Anti-aircraft guns in deck mounts
on side, evenly spread, 4 raised mounts
Weight of broadside 14,829 lbs / 6,726 kg
Shells per gun, main battery: 150

Armour:
- Belts: Width (max) Length (avg) Height (avg)
Main: 11.8" / 300 mm 541.34 ft / 165.00 m 13.12 ft / 4.00 m
Ends: Unarmoured
Main Belt covers 100 % of normal length

- Torpedo Bulkhead and Bulges:
1.38" / 35 mm 501.97 ft / 153.00 m 28.38 ft / 8.65 m

- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 17.7" / 450 mm 11.8" / 300 mm 12.6" / 320 mm
2nd: 0.98" / 25 mm 0.79" / 20 mm 0.98" / 25 mm
3rd: 0.20" / 5 mm 0.20" / 5 mm 0.20" / 5 mm

- Armour deck: 6.10" / 155 mm, Conning tower: 11.81" / 300 mm

Machinery:
Oil fired boilers, steam turbines,
Geared drive, 4 shafts, 136,386 shp / 101,744 Kw = 31.00 kts
Range 10,000nm at 15.00 kts
Bunker at max displacement = 4,801 tons

Complement:
1,400 - 1,821

Cost:
£18.055 million / $72.221 million

Distribution of weights at normal displacement:
Armament: 1,742 tons, 4.4 %
Armour: 13,302 tons, 33.7 %
- Belts: 3,523 tons, 8.9 %
- Torpedo bulkhead: 726 tons, 1.8 %
- Armament: 2,773 tons, 7.0 %
- Armour Deck: 5,985 tons, 15.2 %
- Conning Tower: 295 tons, 0.7 %
Machinery: 3,735 tons, 9.5 %
Hull, fittings & equipment: 15,604 tons, 39.5 %
Fuel, ammunition & stores: 4,717 tons, 11.9 %
Miscellaneous weights: 400 tons, 1.0 %

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
57,006 lbs / 25,857 Kg = 27.1 x 16.1 " / 410 mm shells or 8.5 torpedoes
Stability (Unstable if below 1.00): 1.16
Metacentric height 5.8 ft / 1.8 m
Roll period: 17.7 seconds
Steadiness - As gun platform (Average = 50 %): 51 %
- Recoil effect (Restricted arc if above 1.00): 0.52
Seaboat quality (Average = 1.00): 1.16

Hull form characteristics:
Hull has a flush deck
and transom stern
Block coefficient: 0.495
Length to Beam Ratio: 8.23 : 1
'Natural speed' for length: 33.56 kts
Power going to wave formation at top speed: 49 %
Trim (Max stability = 0, Max steadiness = 100): 44
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: 29.53 ft / 9.00 m
- Forecastle (20 %): 22.97 ft / 7.00 m
- Mid (55 %): 19.69 ft / 6.00 m
- Quarterdeck (20 %): 19.69 ft / 6.00 m
- Stern: 19.69 ft / 6.00 m
- Average freeboard: 21.44 ft / 6.54 m
Ship tends to be wet forward

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 85.4 %
- Above water (accommodation/working, high = better): 148.9 %
Waterplane Area: 53,015 Square feet or 4,925 Square metres
Displacement factor (Displacement / loading): 113 %
Structure weight / hull surface area: 197 lbs/sq ft or 960 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.99
- Longitudinal: 1.14
- Overall: 1.00
Hull space for machinery, storage, compartmentation is adequate
Room for accommodation and workspaces is excellent

[Shark7]

Ok, I've revised my design a bit, improving the areas you suggested and increasing the main battery size. I also swapped to using the 3.03beta version on Springsharp which has much better interface. The new ship:

Mino, Japan Battleship laid down 1938

Displacement:
43,901 t light; 46,552 t standard; 49,771 t normal; 52,346 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
(880.12 ft / 853.02 ft) x 91.86 ft (Bulges 101.71 ft) x (33.46 / 35.04 ft)
(268.26 m / 260.00 m) x 28.00 m (Bulges 31.00 m) x (10.20 / 10.68 m)

Armament:
9 - 16.14" / 410 mm 45.0 cal guns - 2,248.72lbs / 1,020.00kg shells, 130 per gun
Breech loading guns in turret on barbette mounts, 1938 Model
3 x Triple mounts on centreline ends, majority forward
1 raised mount - superfiring
20 - 3.94" / 100.0 mm 65.0 cal guns - 33.83lbs / 15.35kg shells, 400 per gun
Dual purpose guns in deck mounts, 1938 Model
4 x 2-gun mounts on sides, forward deck aft
2 raised mounts - superfiring
6 x 2-gun mounts on sides, aft deck forward
2 raised mounts - superfiring
72 - 0.98" / 25.0 mm 60.0 cal guns - 0.52lbs / 0.24kg shells, 2,000 per gun
Anti-air guns in deck mounts, 1938 Model
24 x Triple mounts on sides, evenly spread
16 - 0.52" / 13.2 mm 76.0 cal guns - 0.08lbs / 0.04kg shells, 2,500 per gun
Machine guns in deck mounts, 1938 Model
8 x Single mounts on side ends, evenly spread
Weight of broadside 20,954 lbs / 9,504 kg
Main Torpedoes
8 - 24.0" / 610 mm, 29.53 ft / 9.00 m torpedoes - 2.476 t each, 19.808 t total
In 4 sets of deck mounted side rotating tubes
2nd Torpedoes
8 - 24.0" / 610 mm, 29.53 ft / 9.00 m torpedoes - 2.476 t each, 19.808 t total
In 4 sets of deck mounted reloads

Armour:
- Belts: Width (max) Length (avg) Height (avg)
Main: 13.8" / 350 mm 511.81 ft / 156.00 m 13.12 ft / 4.00 m
Ends: Unarmoured
Main Belt covers 92 % of normal length
Main Belt inclined 15.00 degrees (positive = in)

- Torpedo Bulkhead - Additional damage containing bulkheads:
2.13" / 54 mm 511.81 ft / 156.00 m 31.27 ft / 9.53 m
Beam between torpedo bulkheads 82.02 ft / 25.00 m

- Hull Bulges:
2.13" / 54 mm 656.17 ft / 200.00 m 13.12 ft / 4.00 m

- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 15.7" / 400 mm 12.8" / 325 mm 15.7" / 400 mm
2nd: 0.98" / 25 mm 0.98" / 25 mm -

- Armoured deck - multiple decks:
For and Aft decks: 5.91" / 150 mm
Forecastle: 4.92" / 125 mm Quarter deck: 3.94" / 100 mm

- Conning towers: Forward 15.75" / 400 mm, Aft 15.75" / 400 mm

Machinery:
Oil fired boilers, steam turbines,
Geared drive, 4 shafts, 152,813 shp / 113,999 Kw = 29.50 kts
Range 10,000nm at 15.00 kts
Bunker at max displacement = 5,794 tons

Complement:
1,665 - 2,165

Cost:
£22.286 million / $89.144 million

Distribution of weights at normal displacement:
Armament: 3,349 tons, 6.7 %
- Guns: 3,285 tons, 6.6 %
- Weapons: 64 tons, 0.1 %
Armour: 16,740 tons, 33.6 %
- Belts: 3,898 tons, 7.8 %
- Torpedo bulkhead: 1,259 tons, 2.5 %
- Bulges: 677 tons, 1.4 %
- Armament: 3,974 tons, 8.0 %
- Armour Deck: 6,013 tons, 12.1 %
- Conning Towers: 918 tons, 1.8 %
Machinery: 4,184 tons, 8.4 %
Hull, fittings & equipment: 19,628 tons, 39.4 %
Fuel, ammunition & stores: 5,870 tons, 11.8 %
Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
69,213 lbs / 31,395 Kg = 32.9 x 16.1 " / 410 mm shells or 5.8 torpedoes
Stability (Unstable if below 1.00): 1.08
Metacentric height 5.1 ft / 1.6 m
Roll period: 18.9 seconds
Steadiness - As gun platform (Average = 50 %): 56 %
- Recoil effect (Restricted arc if above 1.00): 0.75
Seaboat quality (Average = 1.00): 1.12

Hull form characteristics:
Hull has a flush deck,
a normal bow and a cruiser stern
Block coefficient (normal/deep): 0.600 / 0.603
Length to Beam Ratio: 8.39 : 1
'Natural speed' for length: 29.21 kts
Power going to wave formation at top speed: 48 %
Trim (Max stability = 0, Max steadiness = 100): 50
Bow angle (Positive = bow angles forward): 30.00 degrees
Stern overhang: 9.84 ft / 3.00 m
Freeboard (% = length of deck as a percentage of waterline length):
Fore end, Aft end
- Forecastle: 20.00 %, 29.89 ft / 9.11 m, 24.44 ft / 7.45 m
- Forward deck: 30.00 %, 24.44 ft / 7.45 m, 19.03 ft / 5.80 m
- Aft deck: 35.00 %, 19.03 ft / 5.80 m, 19.03 ft / 5.80 m
- Quarter deck: 15.00 %, 19.03 ft / 5.80 m, 19.03 ft / 5.80 m
- Average freeboard: 21.36 ft / 6.51 m
Ship tends to be wet forward

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 69.8 %
- Above water (accommodation/working, high = better): 129.1 %
Waterplane Area: 57,312 Square feet or 5,324 Square metres
Displacement factor (Displacement / loading): 117 %
Structure weight / hull surface area: 239 lbs/sq ft or 1,167 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 1.14
- Longitudinal: 1.20
- Overall: 1.14
Excellent machinery, storage, compartmentation space
Excellent accommodation and workspace room

[JuanG]

I personally prefer version 2, as I feel that v3 tends to be a little too 'generous' sometimes. Still, your definately right in the it has a bunch of nicer tools included.

A few comments on your newer design if I may;
-Why the overall hull strength of 1.14? This is wasteful, and means the hull is overbuilt. Some people like to leave 1.01/1.02 to support extra things like AA guns, but its really not necessary on a hull that size.
-Stability is better, but still below 1.1.
-No Miscellaneous weight allocated on this design. The last one had 250tons which is a reasonable reserve. While you dont really need it since youve got that excess hull strength, it would probably be more efficient to do it the other way. A decent rule of thumb is 50-100tons per 10,000tons of ship.
-Minor point, but why not increase the turret faceplates some. Its some of the cheapest armour you can get weight wise, and another 50-100mm would not hurt at all.
-Why the torpedoes!?!?

Otherwise though, its a nice designs, something of an Japanese South Dakota or Iowa hybrid...

[Shark7]

ORIGINAL: JuanG

I personally prefer version 2, as I feel that v3 tends to be a little too 'generous' sometimes. Still, your definately right in the it has a bunch of nicer tools included.

A few comments on your newer design if I may;
-Why the overall hull strength of 1.14? This is wasteful, and means the hull is overbuilt. Some people like to leave 1.01/1.02 to support extra things like AA guns, but its really not necessary on a hull that size.
-Stability is better, but still below 1.1.
-No Miscellaneous weight allocated on this design. The last one had 250tons which is a reasonable reserve. While you dont really need it since youve got that excess hull strength, it would probably be more efficient to do it the other way. A decent rule of thumb is 50-100tons per 10,000tons of ship.
-Minor point, but why not increase the turret faceplates some. Its some of the cheapest armour you can get weight wise, and another 50-100mm would not hurt at all.
-Why the torpedoes!?!?

Otherwise though, its a nice designs, something of an Japanese South Dakota or Iowa hybrid...

I still haven't quite gotten the art of balancing stability vs seakeeping down yet, I fix one, and get the other too low. It also shows in my overengineering of the ship. [:D] Let me see if I can't make a few more small changes and get this down right.

Torpedos...given the Japanese fascination with them... And the fact that Kii and No. 13 classes were designed with them originally, I'm going with the idea they might include them. Plus I like torpedos. [;)]

[Shark7]

And Version 3:

Mino, Japan Battleship laid down 1938

Displacement:
42,218 t light; 44,833 t standard; 47,982 t normal; 50,500 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
(881.41 ft / 853.02 ft) x 91.86 ft (Bulges 101.71 ft) x (32.81 / 34.36 ft)
(268.65 m / 260.00 m) x 28.00 m (Bulges 31.00 m) x (10.00 / 10.47 m)

Armament:
9 - 16.14" / 410 mm 45.0 cal guns - 2,248.72lbs / 1,020.00kg shells, 130 per gun
Breech loading guns in turret on barbette mounts, 1938 Model
3 x Triple mounts on centreline ends, majority forward
1 raised mount - superfiring
20 - 3.94" / 100.0 mm 65.0 cal guns - 33.83lbs / 15.35kg shells, 400 per gun
Dual purpose guns in deck mounts, 1938 Model
4 x 2-gun mounts on sides, forward deck aft
2 raised mounts - superfiring
6 x 2-gun mounts on sides, aft deck forward
2 raised mounts - superfiring
72 - 0.98" / 25.0 mm 60.0 cal guns - 0.52lbs / 0.24kg shells, 2,000 per gun
Anti-air guns in deck mounts, 1938 Model
24 x Triple mounts on sides, evenly spread
16 - 0.52" / 13.2 mm 76.0 cal guns - 0.08lbs / 0.04kg shells, 2,500 per gun
Machine guns in deck mounts, 1938 Model
8 x Twin mounts on side ends, evenly spread
Weight of broadside 20,954 lbs / 9,504 kg
Main Torpedoes
8 - 24.0" / 610 mm, 29.53 ft / 9.00 m torpedoes - 2.476 t each, 19.808 t total
In 4 sets of deck mounted side rotating tubes
2nd Torpedoes
8 - 24.0" / 610 mm, 29.53 ft / 9.00 m torpedoes - 2.476 t each, 19.808 t total
In 4 sets of deck mounted reloads

Armour:
- Belts: Width (max) Length (avg) Height (avg)
Main: 13.8" / 350 mm 554.46 ft / 169.00 m 12.30 ft / 3.75 m
Ends: Unarmoured
Main Belt covers 100 % of normal length
Main Belt inclined 15.00 degrees (positive = in)

- Torpedo Bulkhead - Additional damage containing bulkheads:
2.13" / 54 mm 554.46 ft / 169.00 m 30.81 ft / 9.39 m
Beam between torpedo bulkheads 82.02 ft / 25.00 m

- Hull Bulges:
2.13" / 54 mm 656.17 ft / 200.00 m 13.12 ft / 4.00 m

- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 20.5" / 520 mm 13.8" / 350 mm 16.7" / 425 mm
2nd: 0.98" / 25 mm 0.98" / 25 mm -

- Armoured deck - multiple decks:
For and Aft decks: 5.91" / 150 mm
Forecastle: 4.92" / 125 mm Quarter deck: 3.94" / 100 mm

- Conning towers: Forward 15.75" / 400 mm, Aft 0.00" / 0 mm

Machinery:
Oil fired boilers, steam turbines,
Geared drive, 4 shafts, 143,416 shp / 106,988 Kw = 29.21 kts
Range 10,000nm at 15.00 kts
Bunker at max displacement = 5,668 tons

Complement:
1,620 - 2,107

Cost:
£21.751 million / $87.004 million

Distribution of weights at normal displacement:
Armament: 3,349 tons, 7.0 %
- Guns: 3,284 tons, 6.8 %
- Weapons: 64 tons, 0.1 %
Armour: 16,762 tons, 34.9 %
- Belts: 3,909 tons, 8.1 %
- Torpedo bulkhead: 1,344 tons, 2.8 %
- Bulges: 677 tons, 1.4 %
- Armament: 4,454 tons, 9.3 %
- Armour Deck: 5,929 tons, 12.4 %
- Conning Tower: 448 tons, 0.9 %
Machinery: 3,927 tons, 8.2 %
Hull, fittings & equipment: 17,680 tons, 36.8 %
Fuel, ammunition & stores: 5,764 tons, 12.0 %
Miscellaneous weights: 500 tons, 1.0 %
- Hull below water: 100 tons
- Bulge void weights: 100 tons
- Hull above water: 100 tons
- On freeboard deck: 100 tons
- Above deck: 100 tons

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
70,110 lbs / 31,801 Kg = 33.3 x 16.1 " / 410 mm shells or 5.9 torpedoes
Stability (Unstable if below 1.00): 1.13
Metacentric height 5.6 ft / 1.7 m
Roll period: 18.1 seconds
Steadiness - As gun platform (Average = 50 %): 51 %
- Recoil effect (Restricted arc if above 1.00): 0.74
Seaboat quality (Average = 1.00): 1.23

Hull form characteristics:
Hull has a flush deck,
a normal bow and a cruiser stern
Block coefficient (normal/deep): 0.590 / 0.593
Length to Beam Ratio: 8.39 : 1
'Natural speed' for length: 29.21 kts
Power going to wave formation at top speed: 47 %
Trim (Max stability = 0, Max steadiness = 100): 41
Bow angle (Positive = bow angles forward): 30.00 degrees
Stern overhang: 9.84 ft / 3.00 m
Freeboard (% = length of deck as a percentage of waterline length):
Fore end, Aft end
- Forecastle: 17.50 %, 32.12 ft / 9.79 m, 26.28 ft / 8.01 m
- Forward deck: 30.00 %, 26.28 ft / 8.01 m, 20.44 ft / 6.23 m
- Aft deck: 35.00 %, 20.44 ft / 6.23 m, 20.44 ft / 6.23 m
- Quarter deck: 17.50 %, 20.44 ft / 6.23 m, 20.44 ft / 6.23 m
- Average freeboard: 22.75 ft / 6.93 m
Ship tends to be wet forward

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 70.9 %
- Above water (accommodation/working, high = better): 141.2 %
Waterplane Area: 56,778 Square feet or 5,275 Square metres
Displacement factor (Displacement / loading): 113 %
Structure weight / hull surface area: 217 lbs/sq ft or 1,057 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 1.01
- Longitudinal: 1.14
- Overall: 1.02
Excellent machinery, storage, compartmentation space
Excellent accommodation and workspace room
Good seaboat, rides out heavy weather easily

[JuanG]

Kii and No.13 would have included them because it was standard procedure to include torpedoes on BBs in that era. None but the Nelsons had them left by the time WW2 came around.

Last design looks good though, interesting choice in choosing to max the hull out at its optimal speed. Suppose thats one way to avoid wasting engine power going beyond it.

[bklooste]

ORIGINAL: Iridium

What happened to Akagi and Tosa in this scenario? Do we assume Tosa's hull was damaged during the earthquake or can both be used in their fast BB/BC configuration?

Dur, just noticed you mentioned they've been built as originally designed. Hmm...

I always did like the 18" BC designs, if one was of the configuration of something like 3 x 2 18" guns, 8 x 2 3.9" guns, ~40,000 tons, 34 Kts...etc

It would make for a decent CV escort and seems on par with Japanese thought on outmaneuvering an opponent to defeat them.

Quite a cruiser killer with those 18" , can you land enough rounds ? At least with an 18" 16K yards is fairly flat tradjectory.

[DuckofTindalos]

The Japs wouldn't have put torpedo tubes on a battleship laid down in 1938.

[JuanG]

18in is really overkill for cruisers. Unless your shooting HE chances are its going to go right through without exploding. A high velocity smaller caliber gun would probably be preferable. Like the 31cm/50, or even the Kongo's 36cm/45.

One concept for a cruiser-killer I had some time ago was a ship carrying a liscensed version of the German 28cm/54.5 from the Scharnhorst. The design was something like 9 x 28cm/54.5, 20 x 10cm/65 and 33knots with moderate armour - it weighed in at the surprisingly light weight of 23,000tons standard.

Another possiblility is as someone said reworking the Fuso/Ise's by removing central turrets, and then using those 16 turrets to produce 5 'super cruisers' with 6 x 36cm/45, 16 x 10cm/65 and good speed. Should also weigh in only around 25,000tons.

[bklooste]

ORIGINAL: Terminus

Build all 4 South Dakotas, with 16-inch guns per the escalation clause. Move up the Iowas.

I think this likely .. Without a Yamato i dont think the Montanas are on the cards mainly because of the quantity of the Japanese line ( even though its inferior ) . How much can you advance the Iowas ? Iowas in 42 would be nice and a challange for the Japanese.

For the Japs, drop the Yamatos. Refit the Ise, Hyuga, Fuso and Yamashiro by removing two turrets from each and upgrading the powerplant to allow 28 knots. Assign the turrets to a new, fast BB design, with 2 ships. Build a couple of B-64s with 31cm guns, if nothing else than to make the US waste money on the Alaskas.

Drop all other capital ship building.

What sort of belt are we looking on these new fast BBs and what speed ? I like cheap options are 14" turrets good enough vs the US ships.

I did some numbers on the B-64 and if you didnt up armour them you could run 4*2*31cm or 3*3*31cm on a Takao class hull with a Tone style powerplant and some extra bulges ( looking at 17K tons for 4*2 and 18K for 3*3). A nice cruiser killer , ok for some bombardment but a lot cheaper than a B-64 . I dont see what the armour buys you anyway except the Alaskas ( except for some night fighting) vs any cruisers you win ( if you can keep the range) , vs a BB your toast. And the US will still build the Alaskas when they see 12" cruisers , display her in mid 1941...

[bklooste]

ORIGINAL: JuanG

18in is really overkill for cruisers. Unless your shooting HE chances are its going to go right through without exploding. A high velocity smaller caliber gun would probably be preferable. Like the 31cm/50, or even the Kongo's 36cm/45.

One concept for a cruiser-killer I had some time ago was a ship carrying a liscensed version of the German 28cm/54.5 from the Scharnhorst. The design was something like 9 x 28cm/54.5, 20 x 10cm/65 and 33knots with moderate armour - it weighed in at the surprisingly light weight of 23,000tons standard.

Another possiblility is as someone said reworking the Fuso/Ise's by removing central turrets, and then using those 16 turrets to produce 5 'super cruisers' with 6 x 36cm/45, 16 x 10cm/65 and good speed. Should also weigh in only around 25,000tons.

I dont think 18" round will go thrugh a cruiser those are big ships , a few roudns should kill one . It is overkill but i would rather sink a CA than an old BB in most cases.

With regard to the cruiser killer have a look at the BC-64 i posted a modified one with standard CA armour at 17-18K sort of a Cruiser Battle Cruiser concept.

I like the super cruisers but what is the smallest/cheapest ship you fit 8 14" guns on ( im no fan of 6 gun ships) ? And the question is how will your battle line deal with the US line ?
The turrets carry far too much armour to fit on a cruiser / light ship. If your looking at redesigning ships also look at the Kaga , Nagato etc.

[bklooste]

ORIGINAL: bsq

Weren't the South Dakotas laid down in 39/40 (not 38)?  Something to do with the CNO not liking the North Carolina design... So if they were laid down in 38, they would need to be repeat NC's.  And if your worry was matching Japanese construction, wouldn't the Admirals favour something more akin to the Montana's instead of the Iowa's - certainly designs with 12 x 16" were looked at when designing the follow on from the South Dakota's.

Does this extend to RN ships as well?  It seems unlikely that their lordships would be happy over the Japanese getting the 70% and that this would be used to fuel the argument to get the Lion's built.

They are laid down when designed , hold it scrap it , complete it - thats up to you , your the CNO here thoguh remember you have more weight and budget because of the 2 Kaga class ships. 38 maybe a bit early for a supersize ship but its an option no Panama transits though. The question you have to ask is Japan has a 26knot battle line with quite a few ships ( 3 Kongos , 2 Fuso , 2 Ise , 2 Nagato (16") , 2 Kaga (16") is the Montana good at fighting this.

Sure you can include the UK , though i would not imaging more BBs i coudl see bigger ones since Japan now has 2 more 16" ships ( from 1922) .