New Mexico-class Battleship

Being new here, I enjoyed the chance to catch up on this interesting discussion, but I have to nitpick a couple of points:

You might note that this is one reason both Tennessee and California with 14" guns were modernized while the 16" gunned West Virginia was the only one of her class that got that treatment and then only because she was so heavily damaged at Pearl Harbor.

how about an US Navy battleship like the Tennessee, California, or West Virginia with their 16" main guns?

The "Big Five" battleships comprised Tennessee and California with twelve 14"/50s and West Virginia, Colorado, and Maryland with eight 16/45s but otherwise similar. As the newest battleships of their generation, they were last in line for modernization, after the Nevadas, Pennsylvanias, and New Mexicos. This was further delayed by the Great Depression, and a relatively modest modernization was just getting underway in 1941. Maryland had been completed by the time of Pearl Harbor, and Colorado's work was in progress; this is why she was in Puget Sound Navy Yard on December 7. The most notable feature was bulging which increased the beam to approximately 106', about the most that could fit through the Panama Canal. Curiously, although new gunnery controls were installed, the ships retained their cage masts, which had been removed in earlier modernizations.

The remaining three ships received a much more extensive reconstruction, starting with bulging to approximately 114'. With our major naval commitment in the Pacific, it was acceptable to have a few ships that could not transit the Canal. This enabled them to be completely modernized, with a complete new superstructure similar to the South Dakota class, dual-purpose secondary armament of sixteen 5"/38s, four Mark 37 directors, heavy 40mm batteries, radar, etc. Their main battery directors were new units originally intended for Cleveland class light cruisers converted to CVLs. In most respects other than speed they were comparable to modern battleships. We might also note that these three did most of the shooting at Surigao Strait.

Tennessee was the first to be done, followed by California and West Virginia after they were raised from the bottom of Pearl Harbor.

 

My understanding is she straddled Rodney early on but not much after that.

 

Great thread, can't belive I haven't stumbled across it before. Thanks guys for the interesting data.

 

Why would this be true? The firing of both ship's main battery is done by an electrical circuit that determines via a stable element when the ship is at zero roll etc. That is, the amount of rolling the ship is doing has next to no effect on its fire. Both ships would have equal quality of fire control and, even if the New Mexico didn't have a Mk 3 radar set installed yet the German Seetakt is of really little value in terms of gunnery accuracy. The wavelength is simply too long for it to be anything more than a help to optical spotting.

One thing that is definitely in the US ship's favor is that it is a much smaller target than the Bismarck. I really think that a battle between the two comes down to who is on target first. Bismarck versus two New Mexicos is almost a certain US victory.

 

A Bismarck/Tirpitz fight against a New Mexico class BB.

Well, my money would be on the Germans at long range.

If they got within "knife range" (less than 10kms), my money would be on the New Mexico. Just for the sheer weight of each broad-side.

Nice thread.

 

The Bismarck did have a main battery of eight 38 cm (15 in) SK C/34 with a maximum range of 36,200 m and twelve 150mm surface to surface as sixteen 105mm antiaircraft guns, at a Speed of 30 K (Gröner, p. 35.)

The Bismarck had a battery of twelve 15 cm (5.9 in) cannons that were designed to be used against ships only. The Kriegsmarine supplied time-fused shrapnel shells for these guns to put up a long-range curtain of fire against approaching bombers. They were useless against high-flying fast bombers and torpedo bombers skimming the surface. They could not be elevated sufficiently and, at six rounds per minute, fired too slowly to be effective. (Bercuson and Herwig, p. 33.)

I don't think the Bismarck would of runaway more like the New Mexico would be seriously damaged. But,

ARMOR PROTECTION OF THE BATTLESHIP KM BISMARCK©
BY NATHAN OKUN
Detailed analysis of the Bismarck's armour protection by naval expert Nathan Okun indicated that the resistance of Bismarck's main armour belt was worse than that on the contemporary battleships because it wasn't sloped and it was rather shallow

ARMOR PROTECTION OF KM BISMARCK by Nathan Okun 9/6/91




Battleship Photo Archive

BB-40 USS NEW MEXICO
1940 - 1941



http://www.navsource.org/archives/01/40d.htm

 

Depending on which radar suite the US BB has I'd probably go just the opposite direction. The rate of fire and flat trajectory of the German guns give them an edje in a "knife fight".

 

Is this the Post your talking about shows your name, as post #25 1st Page. Mine shows POST #26 second page I also checked the
other Post and read the rest of the MSG, So All is Good.

I know, "God Done Spaniard"

 

All is good.

When I clicked on the message with your name, it brought me automatically back to my #25 posting. Until I logged off of the forums and came back into the forums. Then it brought me to the correct posting.

 

Actually, if you look at the danger zone created by the fall of shell at typical battle ranges the "flat shooting" German guns are a liability because their shallower angle of fall decreases the chances of hitting slightly over ones falling at a steeper angle. It isn't a great difference, but its there.

 

I've also seen references to the New Mexicos' seakeeping problems, though I can't put my hand on it at the moment. The fire control system did include a stable element which should in theory compensate for the ship's motion, but perhaps there was a bit of lag time in a 1930s electro-mechanical computer. I'm reminded of the gyro-stabilizer in the Sherman tank that....almost....kept the gun on target while firing on the run. I recall it being mentioned in connection with the Tirpitz-New Mexico scenario, will let you know if I find more. We did assign two battleships in that instance, but part of it was just not needing or wanting to take a chance in a one-on-one fight.

 

On fire control the US system uses a series of servos and syncros to allow the rangefinder, stable element, and computer to automatically slave the turrets and guns in both train and elevation. So long as the pitch and roll are not violent the ship's motion is almost irrelevant.
The sea keeping issue revolves mostly around this class being "wet." That is in heavier seas the after deck (lower portion aft) was often awash. Waves would be breaking over the bow and some degree of flooding of turret 1 could be expected along with possible minor flooding through other hatches, ventilators etc., of spaces below forward.

Actually, this control system is more advanced than the Bismarck's not to mention more reliable. The German system has most of the same features but only automatically sets elevation. Turret train is still follow the pointer. The German system uses mag amps instead of servo / syncros making it more complex in terms of system components and more prone to problems associated with complex systems.

 

Actually from what I've seen presented a close range just the opposite is true.

 

The problem is that in WW 2 naval combat "close range" was not going to happen before one side or the other was blown out of the water. There are a few exceptions, almost always at night and pre-radar, but normal open ocean battleship combat? The range is going to be 15,000 to 25,000 yards and there a lower velocity heavier round is better.

 

There are some over on the kbismark forum that are arguing otherwise but I tend to agree with you on this. Indeed I believe the US doctrine was to fight at ~27K yards and that was pre radar. With radar especially some of the lessons learned in 43 and 44 I suspect they would have preferred to fight over 30K. On the other hand the question I was addressing was close range which I'd consider well under 20K yards for BBs.

 

Throw weight is more important in long range battles where deck penetration and shell splash come into play; but sub 20K yards, it is RateOfFire and the Bismarck can fire much quicker. The 14” is a good gun at sub 20K range and 12 is better than 8. For internet discussion let’s say the Bis can put out a broadside every 25 seconds and the USN BB can do it in 35 seconds. Toss in the an additions 2.5% for single gun miss fires on the triple turrets and the rough ROF is dead even, the Bis has slightly heavier and faster shell. No bigs at that range. So main guns it is a dead heat. sub 20K IMO.
Now vertical armor, flotation. I believe most of the USN big 5 did not receive hull bulges before 42 and some even as far out as 43 re-commissioned in 44. Pre hull bulge, the ships were overloaded with the main deck sitting 5.5” lower than intended. A single major hit could potentially put the main deck below the water. I think it is safe to say the Bis would and did take many many major hits before the deck was awash but yes the turtle deck it low but protected by the belt. Vertical hull there is NO comparison here, to push a shot into the Bis internals, maybe even the Yamato could not do it sub 20K, belt sure, but the main turtle deck is behind that at a 45 degree incline. Can’t see it happen. yes a hole in the belt is bad, but not as bad as a hole in the belt that leads to the engine room, and this just can’t happen on the Bis. So the Bis can be mission killed by main battery and control tower destruction (Bis has two of these), but it is going to be hard to actually sink the ship with close range gunnery. As noted about the USN big 5 are all overweight and it will not take much to put the deck awash, the slightly thicker USN BB belt is not doing much. Just about any 11” and above can go through just about any vertical armor (I’ll leave angle belt for another day). So flotation: Bis by a huge margin, maybe more than any other ship. USN big 5 BB, um very to extremely poor. Maybe the worst. Vertical penetration of belt, bout even, however no way to get a shell into the Bis’s internal. So Bis by a huge margin, maybe the best, USN big 5, same as almost all other BB. Advantage Bis.

Potential for mission kill. Here we have 4 turrets vs 4 turrets. Biz turrets are much smaller with nice angle, Bis has an advantage but this is really roll of the dice. The Biz has a very heavy coning tower, not sure if the ship could have actually been steered from rear fire control tower. At close range one may argue the large heavier tower of the Bis is actually a drawback. I’ll give a slight advantage Bis.

So far:
Primary weapon sub 20K about even,
Flotation: Bis by a huge margin
Vertical armor: Bis by huge margin, near impossible to achieve a critical hit sub 20K, but hey any BB hit that goes through the belt is not going to be fun.
Mission kill, roll of the dice, IMO slight advantage to the Bis, for two control towers and smaller better angled turrets.
Secondary and the Bis even has a decent tertiary gun system. Here the ancient secondary system from either ship is going to be much better than the DP 5”. Bis has a whole lot of “wasted” armor over the hull. 6.5” in memory serves this should be proof against the big 5’s 5” secondary. The twin mounting on the deck is a better place to put the gun for sea keeping and range. So if we are talking pre-rebult USN ships their secondaries are useful but unable to damage for the most part the Bis, the Bis’s on 5.9” should be able to swiss cheese any non main armor place topside including the secondary guns on the USN BB. I don’t know about each USN ship but in general these follow the post WW1 design as does the Bis of having armor above the belt. Say 5”. The situation is even worst after USN rebuild as the DP 5” just is not a good gun in a BB slug out especially against the Bis with armor over everything. IMO there would be a strong potential for the Bis’s secondary guns to mission kill a USN BB due to topside damage / flotation damage. At close range. Let’s see Bis has 6 guns at 7RPM = 42 rounds a minute at a very fast 2,871 ft / second vs either no plate of 5” of plate. Post rebuild the USN BB have no protection at all for the DP guns. So I would expect a post rebuild USN BB to lose all secondary batteries relatively quickly. I would add post rebuilt the STS steel on the hood bulge is not keeping out the 5.9 either, so expect flooding from any hull hits into bulge space and these are “bad” spaces to have flooded as it is far outboard of the ships center. All in all pre-rebuild either side’s secondars can really tear up the ship topside outside of major plate, the Bis’s 5.9 should be able to render the USN’s 5” upper plate useless at some range? while the Bis’s own 6.5 inch plate would provide nearly complete protection from the USN’s 5” 51 caliber, also a really great gun.
http://www.navweaps.com/Weapons/WNUS_5-51_mk7.htm
Overall: both ship’s secondary are killer weapons. But the Bis has thicker upper belt armor and a bigger secondary gun. Advantage Bis, and this would become more telling as the USN’s own secondary would be whipped out. After rebuild the USN will be at a major disadvantage as the bulges can be penetrated by a 5.9” gun and the secondary DP are now completely unprotected from a 5.9” gun. Advantage Bis in this case by a significant margin.

So how does this play out? Alt-History, USN invades Norway, the Bis sets out at night under near gale conditions to interrupt the southern landing. The Bis out runs the intercepting South Dakota and North Carolina, only to run into the old USN BB assigned for shore support. The Bis needs only to put enough damage on the USN BB to mission kill it, the USN BB has to put enough damage on the Bis to render her too slow to escape the screen SD and NC that are now say 30 miles away looking for here. Under these conditions, battle would start at 20 K and in the confusion shrink down to 15 or 10 K as the Bis would only be attempting to disengage so she can put some hurt on the transports. So say a good 15 minutes of confused fighting. IMO given average luck both ships would lose a main turret and have some topside shot away and a few belt hits. Bis would go down to say 26 knots and retain enough firepower to deal with transports, the USN BB would go down to 15 kots and be in serious danger of outright sinking. To my mind the Bis would have the greatest chance of achieving a mission, than the USN BB would have of putting enough damage on her to let other warships catch and kill the Bis.

Alt_History, the USN invades Norway, the Germans pull a hasty retreat to the surprise of the American’s. The Bis is assigned rear guard to the evacuation convoy making 8 knots. The closest USN BB say Arizona is dispatched to intercept and destroy the barges. In this case the Bis will use her speed to cross the Arizona’s T one or more times. Scenario 1 Bis keeps the range open uses speed to cross Arizona’s T on a continuous basis. That puts 6 14” guns vs 8 15” guns. In all probability a penetration of the traverse bulk head by a 15” would put one or both front Arizona turrets out of action ( or blow the ship up), ending any hope for the USN BB to intercept. There is IMO a much less of a chance of a 14” going though the Bis’s thin deck and dropping the Bis speed 5 to 10 to 15 or more knots. We are talking 160K ship HP vs 40K ship HP or something like that. It would take some incredible hit(s) to see that much internal damage to the Bis, but certainly possible due to Bis’s thin deck. 90 to 95% change the Arizona is put out of action, but there is a chance for the Arizona to critically damage the Bis, Of course the USN has plenty of BB to play the odds.
Scenario 2, The Bis uses its higher speed to cross the Arizona’s T maybe more than once but closes the range, here I can see both ships taking far more damage. It would be very difficult for the Arizona to damage the Bis enough at close range to reduce her speed below 21 knots. The Bis should be able to put enough flotation damage onto the Arizona to sink her. Likely outcome Arizona sinks, Bis is down to 25 knots and has two turrets and much of the topside blow out and smoking and leaking badly. One year in drydock. So in this case, the Bis is much more likely to take LOTS of damage, the Arizona is more likely to sink. But the Bis is unlikely to sink or take enough damage to reduce her speed to a point that the Arizona could intercept the convoy.

Due to Bis’s better speed it is hard to envision any other time that the Germans would risk a modern surface raider vs a post WWI war tub. Especially a USN war tub that got buku guns and some thick armor. In all other cases the Bis turns and runs as there is NOTHING to be gained by taking on a USN big 5 ship.

 

Navweapons list Bismarck as being able to shoot every 20-26 seconds and New Mexico as able to fire every 30 seconds.

Not sure especially at this point in her career New Mexico should have any more problems than Bismarck would with her guns.

The only reasonable trajectories at those ranges that result in engine room are underwater ones I believe. Bismarck is certainly as vulnerable to those as New Mexico.

Not to mention progressive flooding. The turtle deck is enough below the waterline that this is a potential problem. If New Mexico is on a bombardment mission she may also be short on AP. This may not actually be good for Bismarck. It would mean that belt hits are unlikely to penetrate but the damage to her uperworks and less armored portion would be much worse.

For flotation you may be correct but I'm not sure the margin is as great as you seem to think.

It's troubling here that Bismarck seems to have lost both of her forward turrets to a single hit from Rodney in her final action.

Perhaps not on anything below the turtle deck but not all critical hits are below the turtle deck.

Bismarck doesn't have a huge speed edge here. Also unless the two were somehow directly behind Bismarck they can cut an angle that will further diminish the speed advantage of Bismarck. Furthermore the SD and NC are likely to have Bismarck on radar before Bismarck knows whether they are battleships or destroyers. Of course in reality there would be a bunch of DDs and cruisers escorting the US BBs as well.
[/quote] ... Bis would go down to say 26 knots
[/quote]
Historically her speed was reduced to this by POW at Denmarck straits due to a single hit (that's one in three) In a short range melee it would be very easy for her to loose even more.

The problem is the way you've set this up would require something very close to stupidity on the part of the USN.

This is frankly impossible in the absence of terrain that limits the Arizona's movement or they are fighting at a few hundred yards.

 

woops I noticed the Arizona has the last 14/45 with a slow rate of fire, the 14/50 is rated at 30 second salvo.... Yep thems alot of shells, that makes it slight advantage USN 14/50 for close and definite advantage far… But there is a speed factor to consider. But yes a Bis speed BB with 12 14” guns would be a handful. Gotta like the USN’s triple turret.

On the internal penetration, under most conditions sub 20k there should not be very many diving hits as the shell would be at a shallow angle and it would take longer travel to get the depth, only the IJN has special noses on the BB shell to level out the shell BTW.

Are you telling me that a penetration of the main belt on a USN BB would not lead into a mechanical space? AFAIK it does in all ships outside of the German turtle deck design.

Yes Anton and Bruno were mission killed by a salvo of 16" guns. How many shells, what type of penetration are all matters of conjecture? Tthe RN’s 16” shell is 500 lbs heavier and slower, making for better potential deck penetration and overall damage. IMO it would be far harder for a USN 14” to do the same damage. I noted in my first scenario it would be the Bis that should / may be able to cross the T of the much slower USN BB many times and in this case it would be 8 15” guns firing across the front traverse bulkhead which could lead to this type of turret killing. In the case of the Bis damage to her allowed the RN to do exactly what an undamaged Bis would do to a slower BB, that is cross the T and fire longitudinally across the slower ship.

Any realistic scenario would have the Bis dictating the approach and range. That means 8 15” guns against 6 14” guns. That puts the 15” guns firing at a bulkhead and a long deck, and puts the USN firing at a belt that has 6.5” of vertical thickness far above the deck, meaning shells would lose about 1/3 of its overall velocity before hitting the turtle deck’s vertical deck, and many hits would have to either go through or glance off the 45 degree wings of the turtle deck. Also this type of T crossing puts Bis’s belt at 20 degree or greater angle vs the USN’s shells meaning there would be little to no penetration of the main belt, kind of an angled belt due to battlefield conditions. The worst possible angle to get hit at is head on, the best possible angle to get hit by is say 20 to 40 degrees off head on. The slow BB is going to be taking it head on, the fast BB is going to be at or near an ideal angle.

No mention so far has been made to speed in relation to shell fall, the Bis is almost 50% faster, that means the radi of where she will be in terms of area in 60 to 120 seconds is significantly greater as area goes up by the square of radi. So that is dunno double the possible places for the Bis to be during shell flight. Double the area means half the straddle probability. Both shells fly at about the same speed so no advantage there.

On flotation, well documented pre-bulge the USN BBs were grossly overloaded. There are notes that say single TT / Bomb and I would assume BB penetration would put the deck underwater. Sorry but reality the Bis took many hits and was still able to steam at speed till the fateful rudder hit. The USN bulges were TT defense and flotation, they would provide little protection from BB or even secondary gun fire; but would flood due to such hits. In the Vanguard and Montana ships, navies went back to external belts, flooding of the bulges due to gun hits is NOT good thing when trying to keep a ship afloat. OK I would note that being overweight does put the internals lower in the water meaning less chance of a diving shell penetration, there is that. IMO the Bis does not have a floatation problem but the USN BB up to and including the big 5 do. Meaning that there is scant room between mission kill and sunk for the USN BB. Lots more room for smoldering hulk for the Bis.
As an offtopic, looking at the massive damage done to the French BB / BC on none protected spaces from BB shells, One has to wonder what a single shell would do to the USN fast BB if the hit was located anywhere in front of the forward bulkhead, as this is all basically sheet metal.

 

Please so much of Nathan's ideas were flawed. The whole decapping deal was just um shall we say WRONG. Even Nathan says the Bis internals can't be penetrated close range by a BB shell. As the Bis is the only ship design that a shell needs to penetrate the belt and then the deck to reach the internals (or dive under the belt).

Also since none, not a one, never happen that BBs would be stanidng at zero offset broadside; the whole angle belt is a canard. A vertical belt is and will be hit at an angle under field conditions. So it really is only thickness no matter what the USN's fast BB designers wished for. Toss in that an overmatched plate (shell wider than plate) does not protect well. The vast majority of field conditions would favor thick, and field conditions do not matter much to thin due to plate overmatch. Well angle would matter if one was fighting say the 11" or 12" BC as these shells do not overmatch BB belts. To sum it up, thick is always thick, and thin with an angle is still thin.

As an aside the German BC better be fighting broadside to broadside at close range to have any hope fn penetrating a BB and only vertical belt BB.... yikes.

Vanguard and Montana are both outside near vertical belt designs.

 

Judging from historical results I'd say that the belt on both ships will play a nearly insignificant role in the outcome and in the amount of damage taken. The deck is far more important in terms of damage control.
As to rates of fire, if I were the US ship captain I'd be firing six round half salvos say every 15 to 20 seconds rather than one full salvo every 30 to 40. Those are realistic times. The reason for this is that there is less lag between salvos this way so I can get my fire on target faster and keep it there. The German captain could be expected to do likewise. The difference is that a six round salvo versus a four round one has a far greater chance of obtaining hits earlier in the engagement.

As for the effect of armor, again historical results show that the "book" values for penetration etc., are not largely relevant. There are numerous instances of glancing hits in fact defeating armor even if the shell itself didn't penetrate. The results of such hits are often nearly as devastating as actual penertrating hits are.

I still say the ship on target first with a couple of solid hits will pretty much be the winner. This is particularly true if those hits reduce the firepower or fire control ability of their opponet significantly. The secondary batteries on both ships will play a minor role of little significance in the outcome. The difference in caliber is nearly irrelevant.