American militarism pre-WW2 and the Ultimate Battleship

[TheMarcksPlan]

The Iowa's were 27 feet - trunnion to rear bulkhead, not including space for rammer and turret control space.

The length of Iowa's guns from trunion, including recoil, was 22ft.


Projected linearly an 18in gun would need 24.75ft.
Ok so 25ft-long gunhouses. That was probably an illustration of 16in turrets. 106ft turret diameter instead 100ft. Same difference.

[TheMarcksPlan]

Main armament was not given AAA elevation because the gears never held up to the stresses of elevating the guns to such angles and always failed. This is the problem run into by the British, Japanese, and Americans.

If you can't get 6- & 8-inch guns to reliably elevate that high, your not going to get 16- & 18-inch ones to do so.

Reference?
Obviously this was solved on the Worcester Class CL's with the their 78 degree elevation. http://navweaps.com/Weapons/WNUS_6-47DP_mk16.php
If you can solve it for 6in you can solve it for larger. Just requires more steel. Weight isn't a huge issue for this ship.

[Takao]

You appear to not quite understand topweight and stability issues, as these are not easily waived away with 'the ship is so big' answer.

You're mistaking my cursory answer to Takao as ignorance of stability. If you or he want to make an argument that the ship would capsize, feel free. I don't feel it's my responsibility to respond in full to any unsupported critique.

As an initial matter, how does this cross-section tip:


The math isn't super complex but basically you'd need to get the vertical axis of the center of gravity beyond one of the lower corners. With the ship at light draft, that'd require at least 45 degrees of tilt. With any ammo loaded or any ballast aboard, much more. So basically you'd need a giant wave inside of a harbor while the ship is light. So don't keep the ship in Tokyo harbor light after an earthquake.

Ummm...Shouldn't the heavy magazines be located in the lower part of the ship to improve stability? You have the lighter her thing areas and stores there instead.

This is what I am talking about. The behemoth will have a very high CG, and be more likely to capsize at angles less than 45 degrees. Not to mention the armor deck being up so high and the two/three tiered turrets.

[TheMarcksPlan]

If you look at the Iowa's turret schematic, increasing the gun angle to 75 degrees or even 85 degrees would only require an extra 8-10 feet. Weight increase would be minimal as it is still covered by barbette armor and the armored deck. The shell and powder flats would need some rearranging, but height increase and weight gain would be minimal at best.

That might be true of the center gun from looking at the cross section. I.e. if you're looking at this view:

But it's not true of the outer guns - the curvature of the barbette would prevent them elevating higher. Just visualize the barbette under this top-view and you can see that only #2 gun can use the full turret depth.


And what do you mean "only require an 8-10ft"? Of barbette diameter? Then you're pushing into the already-thin torpedo bulge. Of turret wall height? That's several thousand pounds of armor and has huge stability implications. Of total magazine-turret depth? Then turrets one and two need a deeper hull or removal of the triple bottom - not a good safety idea under your magazines. As you can see, turrets 1&3 extend to near the hull bottom:



You could probably do two triple 16in turrets on your lines if both were elevated. But not three, and not worth it. You need more hull depth and width, which you'd probably want to use for something other than high main gun elevation.

[TheMarcksPlan]

Ummm...Shouldn't the heavy magazines be located in the lower part of the ship to improve stability? You have the lighter her thing areas and stores there instead.

Ummm... they could be. That's a two-minute sketch for the purpose of showing volume ratios. But they need not be. Again, feel free to make a mathematical model of the ship tipping at <45 degrees. IMJ a simple glance shows that even if the ship is top heavy it's more stable than many other ships even with light draft:

[OpanaPointer]

I'm still not convinced that a super-Yamato would have been useful.

[TheMarcksPlan]

I'm still not convinced that a super-Yamato would have been useful.

Let me know which of the following uses you doubt:

1. Deterrence. Even if you believe that the ship wouldn't have been decisive in combat, prevailing naval doctrine at the time - including within the IJN - viewed battle-line confrontation of heavy units as the ultimate hinge of naval supremacy. The point of this ship is that Japan could not match it; therefore Japan can't launch the Southern Strategy.

2. Surface superiority. Can't be beaten by opposing surface fleets.

3. Air indomitableness - isn't vulnerable to air attack, at the very least is invulnerable to the largest carrier air arm feasibly foreseeable.

--------> From 2+3 combined, the ability to control any sea lane whenever deployed. The ability, for instance, to isolate any Japanese move on the Philippines within days of such attack (if the attack hasn't been deterred/destroyed by the ship's presence in Manila Bay).

4. Strategic mobility - previously discussed use as a cargo/troopship that can deploy through any defenses.

5. Shore bombardment - making it impossible for any enemy land forces to defend within 20 miles of the sea.

6. AAA fleet duty - puts up an impenetrable AAA shield over fast-carrier task force.

7. Fleet support - can refuel and replenish a giant fleet.

[OpanaPointer]

Remember how many dive bombers hit Yamato?

[OpanaPointer]

I see "HUBRIS" floating over these monsters in bright Carnaby St. paisleys.

[Richard Anderson]

This is a polite request that people avoid comments that could be construed as derogatory in any way. Whilst this post does not conform exactly to the 'What If' criterion with regards to offering background to how the US arrives at a situation where it feels the need to build such ships, I did allow it to stand as people seemed interested in the concept of such ships, or rather the reasons all nations stopped short of anything near this sort of idea. If people cannot be polite, or accept reasoned criticism, then the post will be locked.

Terry Duncan

Okay, so how about:

"The first obstacle to this cubic escalation of battleship scale is harbor depth. Luckily, the U.S. possessed on both coasts at least one sheltered harbor that could resupply a gargantuan ship up to 100ft draught: Puget Sound and Tacoma Harbor on the West Coast and Massachusetts Bay and Provincetown in the East."

No, the Puget Sound Naval Shipyard is not workable as a "sheltered harbor" for a ship of "up to 100ft draught". Rich Passage shallows to under 40 feet east of Point Glover...and I would ask anyone who has ever taken the ferry from Bremerton to Seattle to rate the chances of such a vessel managing to make the u-turn through the 800-odd foot wide Rich Passage to Sinclair Inlet. Nor is "Tacoma" viable. Although the ship channel is plenty deep, the problem is Commencement Bay is too deep, averaging about 400 feet, and it shallows very quickly...the piers stand in about 32 feet of water or less. Pier 91 in Smith Cove is similar, standing in less than 40 feet of water. Oh, and that is after 100-odd years of dredging, the sites were shallower in the 1920s and 1930s. There is also the not so minor detail that only Bremerton was an actual Navy base, using any of the others means the added expense of building facilities to support the USS Behemoth.

I am also not sure where the idea "Massachusetts Bay" is 100 feet deep came from? The North Channel today shallows to under 35 feet, the South Channel to under 33 feet, with a very narrow throat between Buoy 5 and 6. Nantasket Roads Channel is currently under 36 feet. Yes, Provincetown Harbor on Cape Cod can be approached through 100 foot depths, but the 100 foot curve runs southwest from Wood End. Saying its "sheltered" is technically correct, if you just need a place to park USS Behemoth while the crew is carousing on shore in the Provincetown fleshpots, but what facilities were at Provincetown to actually support USS Behemoth? Sorry, rhetorical question, the answer is none. Does everything get loaded into lighters and hauled across from the Boston Maval Shipyard?

Oh, and no, Hampton Roads doesn't work either...all the channels in and out at the time were under 35 feet.

All these areas require massive infrastructure investment for basing, which goes back to the question of why? Why would anyone want to do this? What would possess the United States collectively and the Navy Department individually, to lose its mind and do such a thing?

[TheMarcksPlan]

Remember how many dive bombers hit Yamato?

Torpedo bombers probably did more of the damage...
Anyway, Yamato's deck armor was within the ship and much thinner (only ~35% of MegaBB's). Per the well-cited Wikipedia narrative of her demise, bombs started fires and wrecked the secondary armament, including the magazines. MegaBB with 2ft deck armor would just shrug off such bombs and none of the primary/secondary armament (also under 2ft of armor) would be damaged.

Torpedo hits caused immediate damage and flooding to Yamato's engine room's; MegaBB's wouldn't be affected. Any damage to torpedo bulges just reduces the amount of ballast that the MegaBB carries - it doesn't even impact her reserve buoyancy.

MegaBB would have literally ~1,000x the AAA defenses put up by Yamato, measured by shell weight. The Allies lost 10 aircraft attacking Yamato; any attack on MegaBB would cost hundreds of planes or even thousands if such numbers were somehow available.

[OpanaPointer]

Remember: Mobility + Offense + Defense = 1

[TheMarcksPlan]

No, the Puget Sound Naval Shipyard is not workable as a "sheltered harbor" for a ship of "up to 100ft draught". Rich Passage shallows to under 40 feet east of Point Glover

As usual, you need to misrepresent a point to criticize it. "Puget Sound" does not mean "Puget Sound Naval Yard at Bremerton" so Rich Passage leading there is irrelevant.

Yes, Provincetown Harbor

Why waste all that time writing? I said Provincetown Harbor and showed a map of its environs.

Hampton Roads doesn't work either...all the channels in and out at the time were under 35 feet.

Ok, might need to dredge a few feet there. Or remove a few turrets from MegaBB. Doesn't change the bigger picture.

All these areas require massive infrastructure investment for basing

Oh like the $590mil spent on bases 1938-45? https://www.ibiblio.org/hyperwar/USN/Bu ... ses-8.html

What you and your gang are forgetting that the U.S. was going to make massive investment in ships, bases, training, weapons development, etc. whether you build megaships or not. By the end of the war we had in commission, in memoriam, on slipways, or in the production line at least ~25 BB's, 35 CV's, ~90 CA/CL, ~500 DD's. Two MegaBB's would cost a small fraction of that fleet to build/man/supply etc.

The ATL/ What If that you're pretending doesn't exist here is: What if the U.S. built to be the global naval hegemon in 1935, instead of just another Great Power? And you're pretending that my proposal is "build MegaBB's only" rather than "MegaBB's plus a (smaller) conventional fleet."

For a given security goal (in this ATL and in OTL WW2 the goal is total naval supremacy) you can build either 1 MegaBB or, say, 10 Iowas. Or one or two balanced carrier/BB/cruiser/DD task forces (with hindsight you'd omit the BB from that mix but not in 1940).

Given 10x Japan's resources, do you build 10x as many CA's, BB's, CV's, DD's etc. as Japan? Or do you maybe build 3x Japan's conventional fleet and fold the other 7x into 4 ships that would cost a fraction of the expense to build, man, supply, and base? And that could destroy Japan's fleet without significant loss, unlike even an unbalanced battle of conventional fleets (See Pacific War, U.S. casualties)?

Remember: Mobility + Offense + Defense = 1

Huh? Not following... If you're suggesting there's a necessary tradeoff for weapon systems between these values, I'd say no. Some weapons are just better than others all around.

[OpanaPointer]

You have one (1) ship. The totality of the ship can be expressed as the sum of mobility, defense, and offense. (You have to shove something, like "habitability" under a head like "Mobility", but the end result is one ship.)

[T. A. Gardner]

The superimposed gun thing was tried before by the USN. It was found to be a complex mess that really didn't work.



The idea isn't new, but it also didn't work.