WesWorld

Well I’m looking at the merits of 7 vs 8 capital ships, reconstructing vs. building new. Etc.

One of the issues I’m having is deciding which category of reconstruction the vessels would fall under- particularly the need or lack of same to upgrade the barbettes. If I can “pay” only 50%, the prospect becomes rather more attractive.

With the Zeven Provincen, RAM stated he deliberately oversized the original barbettes. RAM stated that 2x345mm would not be a problem because of this.
I asked Rock Doctor how to evaluate if the new 360mm guns would also fit, and the rule of thumb given was to use the shell size. Unfortunately the Zeven Provincens were done prior to being able to specify such things.

Dutch practice was to oversize the shells. The 345mm is 20% over and the 381mm is 17% over, averaging 18.6%. For a 310mm round that would be 489kg.

Presuming that the original design was essentially a triple 310mm turret mounting only 2 guns, and that the 310mm shells were supersized in the 18.6% range like the rest of the Dutch shells, then the original structure could handle roughly 3x489= 1467kg.

Does this sound reasonable enough so that I can go start playing with redesigns on the basis that as long as the shells<1467kg, I do not need to increase the barbettes?

Uh, I´m not sure if this is a good rule of thumb as shell weight is not the same as shell size - and the latter dictated dimensions of tools in the handling rooms, the size of the hoists and everything else getting in contact with the shells. The whole ammo trunk has to be re-designed. And that´s just because of the different shells.

Different guns mean different sizes of the mounts and guns as well. Completely different forces are "at work" when firing a much larger gun. These forces will have a huge impact on the ships structure in general and especially in the area around the ships barbets and the barbets themselfs.

I think it is necessary to compare some real life data regarding guns sizes, their weights and the weight of their mounts and turrets. It is a HUGE difference if we´re talking 30,5cm or 38cm guns (of 36cm in your case).... see here !

True, but it WAS done or planned to be done in some cases (Mogami was upgunned, and the "Twins" were designed to be upgunned). And the "Twins" were going from 28cm guns to 38cm guns, an even larger jump than the one in your picture.

IF the Zeven Provincien's were fitted with a barbette suitable for a triple 310mm mounting, based on the example of Scharnhorst there should be absolutely no problem replacing that mounting with a twin 360mm mounting. Based on the Scharnhorst example, there'd be room for something even larger than a twin 380mm mounting, since Scharnhorst was expected to go from a triple 283mm to a twin 380mm.

To a point, I agree with Hoo, it's not the weight of the shells that's really the issue. See Gneisenau as an example: she was designed to be upgraded and she was in the process of being upgraded when she was bombed. Originally, her mountings were triple 283mms firing 330 kg shells. The replacement mountings were twin 380mm mountings firing 800 kg shells. The weight of shells is much higher in the replacement mounting than in the original.

Mogami shows the same pattern: the original triple 15.5 cm mountings fired 55.87 kg shells, the replacement twin 20.3 cm mounts fired 125.85 kg shells, the replacements are much heavier in total weight of shell than the original mountings.

Please note that the idea of upgunning the TWINS came up when somebody noticed the diameter of the barbets necessary for either a 28cm triple or a 38cm twin where similar (not identically!). Still it would have made a huge re-build necessary. The converion of GNEISENAU as planned shows a completely new and longer bow (to carry the additional weight of the 38cm twins) and a complete rebuild of her interiors to supply the new guns (stucture, tools and handling).

IIRC the modifications to the MOGAMIs were less extensive because the 15cm triple and the 20,3cm twin where much closer in weight and size (including armor that is).

I wouldn't take shell size to be an indicator. Bore size would be better and then compare with historical precedence.

I can see no problems with going to duple 345mm or 360mm. 345mm makes more sense as it avoids yet another calibre for the Netherlands.

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One of the issues I’m having is deciding which category of reconstruction the vessels would fall under- particularly the need or lack of same to upgrade the barbettes. If I can “pay” only 50%, the prospect becomes rather more attractive.

Has to be 75% because of the removal of Q turret and barbette.

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Has to be 75% because of the removal of Q turret and barbette.

Agreed, if Q turret is removed and replaced with powerplant machinery, the upgrade will cost 75% (Infrastructure Rules v1.7, section 2.2.2.5). If Q turret is NOT removed and replaced with powerplant machinery, then it could be a 50% job.

A couple of answers-


A)-Yes, RAM specifically planned for the ships to be upgunned to at least 345mm and pictured the ships accordingly. He reiterates this in the Rebuild clauses in Cleito Treaty thread , Posts # 10 and 15.

B)-There are several reasons I am exploring the 360mm is
1) To see if it's an option.

2) If its an option, what are it’s performance parameters ? To do that I need to establish how big/heavy a shell I can use for the 360mm. Thus the question re: the rule of thumb. 1467/2 = 733.5kg shells.

3) The larger shell should yield a better weapon for the future. However, it may be only slight. I was planning on using BigGun to compare the 360mm and 345mm to see what the "gain" is. I am wondering if a slower heavy shell might be a sufficiently better deck penetrator to matter. The 345mm has a +20% weight shell at 681kg, so should have pretty good characteristics on it’s own.

I did a search for super heavy and found somebody hoping that doesn’t' occur until 1935, so I was going to stay to the Dutch "historical" range of +17-20%. Unless someone says this might be a reasonable time for them to go to superheavy.....

4) Even if the ZPs are reconstructed with 345mm, before committing to that I need to figure out what will replace the Ijeelsijks (1909 BC) and what THOSE will mount.

5) Should the 360mm prove substantially better, it may be advantageous to plan on upgunning the DeRutyers at some point.

6) It gives me a good reason to delay/cancel doing both ZP's while a new gun is developed. That way I could do RA’s (?) suggestion of the 1xZP, 2x New vessels mounting 381mm, which may well be superior to 4x26,000ts. Though I did come up with a nice 6x360mm, 26,000 tonner, armored in RAM's style.

C)- 50% vs. 75%
The 75% clause states :
Replacement of main barbette with powerplant machinery: D

I was thinking of watching powerplant size to ensure it remained the same, and razing the barbette above the armor deck and plating over the hole to remove the barbette weight. That should still be in the 50% range, no? Or have I wandered onto uncharted reefs again?

Superheavy shells; The RN experimented with them in 1920/21 then disposed of them due to their bad characteristics.

The USN experimented with 20% overweight (2700lb) and 40% overweight(3150lb) shells for their 16" guns in the 1930s. The 40% overweight version wasn't persued because of a tendancy to break up at oblique angles of impact. The so-called "hammer effect" affected both these shells because of the extra length. Basically at higher impact obliquities they tend to break up and are rendered ineffective.

Compare the British 16"/45 Mk II shell (i.e. bigger 14"/45) with a shell weight of 2375lb to the USN 16"/45 with 2700lb shell.

US 16"/50 Mk 8 =16.7/3.5@20.000yds =13.0/5.3@30.000yds
US 16"/45 Mk 8 =14.8/3.6@20.000yds =11.4/6.5@30.000yds
UK 16"/45 Mk II = 17.6/3.3@20.000yds =13.4/5.6@30.000yds
UK 15"/42 Mk17B =15.9/2.9@20.000yds =12.0/5.4@30.000yds

As you can see, the RN shells and guns have better belt penetration (1-2" better) and the USN guns better deck penetration (0.5" or so). Then compare the bursting charge of the shells. The larger weight of the USN shells prevents them from carrying a large amount of explosive. 40lb bursting charge vs. 60lb for the 2375lb shell.

So; There was basically no advantage (probably a slight disadvantage) in having a 2700lb shell for penetration. There was a 50% disadvantage in having the 2700lb over a normal shell.


Netherlands navy with 381mm, 360mm, 345mm and 320mm guns? Doesn't sound good.

I'd stick with 345mm for upgunning ZP and then put 381mm on the replacement for the Ijellsijks.

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I was thinking of watching powerplant size to ensure it remained the same, and razing the barbette above the armor deck and plating over the hole to remove the barbette weight. That should still be in the 50% range, no? Or have I wandered onto uncharted reefs again?

Q barbette would be an integral part of the ship's structure that can't just be plated over.

RA, what's your source for the British data? Certainly the USN was sold on the usefulness of the superheavy, see the fact that all of the later-1930s 6" and larger guns used a superheavy APC shell.

Which British data?

The penetration data is from Nathan Okun here which is the data to use for penetration calculations.

Campbell has a 4-part article in Warship (~ No.12-15).

There is an article on the USN development by Lewis in Warship International No.4

Is there anything that you particulary want to know?

The reason I asked was because the numbers you gave did not match my understanding of how shells penetrated, nor did they match other numbers that I'd seen. But FACEHARD is a reputable source, no argument there. I just wish the creators of the tables had include the new gun muzzle velocities that they used with their tables.


Looking at the same tables, what they appear to show is two things: 1, the (admitted) preference in the program for British and German shells in terms of accurate predictions, and 2, either flaws in the Mk 8 1-5 shells or fairly large improvements in the Mk 8 6-8 shells (note the differences with the Mk. 8 6-8 shells in the next table: effective penetration jumps 1.9" at 20,000 yards, with deck penetration remaining the same).

Those numbers don't look logical. How is it accounted for the difference in the penetrations? Angle of attack? Amount of powder used? Heavier usually means more penetration. It doesn't do as well at the same ranges at standard shells at extreme ranges due to the angle at attack if I remember correctly.

Of course the other item is that hitting at 30,000 yards has pretty much been listed as improbably in naval combat. The upper (known) limit was 26,100 yards.

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Q barbette would be an integral part of the ship's structure that can't just be plated over.

Drat, I was thinking that by maintaining the barbette between the bottom and the strength/armor deck -i.e. by not impinging on that area with machinery- I would be addressing the structural issue. Having to sport several hundred tons of empty barbarette in the misc. wieght to account for an empty Q willimpact the viability of a 50% rebuild model.

On the % filler- I was under the impression that this was more a manufacturing choice by the shell designers.

As I recall, the USN shells were built to go through virtually anything, and successfully penetrated plates meant for Shinano's turret face, while the post-war tests found RN's shells deformed against slightly overcaliber plates. While in the Richelieu's original shells the barrel failures have at least in one place been blamed on the large internal cavity of the gas shells allowing the shell to deform in the barrel, ostensibly fixed by filling them with concrete.

My expectation would be that the future India, Phillipino and Japanese ships will be 380mm, and that a 360mm shell may prove more useful than a 345mm.

The expected scenes of action are either very close range near islands- in which case gun size is not terribly important- or longer oceanic ranges where the lighter ships could be kept in the rear and deck penetration would matter. The SATSUMA forces will not have speed to dictate range, and are currently believed inferior in that respect.

As for the mixture of shells in the fleet- regretable, but temporary. The 310s would be replaced, the 320s would quickly follow. Leaving 345, 360, and 381.

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Those numbers don't look logical. How is it accounted for the difference in the penetrations? Angle of attack? Amount of powder used? Heavier usually means more penetration. It doesn't do as well at the same ranges at standard shells at extreme ranges due to the angle at attack if I remember correctly.

They are perfectly logical. Velocity is better for penetration than mass. The amount of Ek transferred to the armour plate is given by;

1/2 * m * v^2 where m = mass and v = projectile remaining velocity

As can be clearly seen the velocity term is more important in deciding the amount of energy delivered to the armourplate.

Now, a heavier shell is better at longer ranges because it has more inertia (i.e. loses less speed);

Impulse exterted on a body = Force * Time = m(change in velocity)

Consider a constant drag force being applied to the shell in flight;

(force * time) / mass = change in velocity

When the mass is large, the change in velocity is smaller over the same period of time.

i.e. at longer ranges (more flight time), the shell loses less velocity and so has more energy remaining with which to penetrate the armour plate.

However, at the shorter ranges (up to 30.000-35.000yds) there is no advantage for the heavier shell because it was travelling at a smaller velocity to start with. Its actually only when the heavy shell starts to accelerate in the dive at long range is there any advantage gained by using the heavier shell.

This is not the end of the story by far, but lets not talk about sectional density of shells, how they perform at different obliquities, how the shape of the shell affects range and penetration....

Hrolf, mv and angle of descent for different ranges are given at the bottom of the tables.

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As I recall, the USN shells were built to go through virtually anything, and successfully penetrated plates meant for Shinano's turret face,

That is impossible. I'm sure the tests showed that the faceplates were actually invulnerable to penetration. The USN shells might be built stronger, they had a thick wall thickness but that doesn't mean they actually penetrate any better. What it means is that the shells stay intact at higher impact obliquities. The German shells were poor for this, USN and Italian shells very good.

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Drat, I was thinking that by maintaining the barbette between the bottom and the strength/armor deck -i.e. by not impinging on that area with machinery- I would be addressing the structural issue.

Having a big hole in the armourdeck(which is probably the strength deck) would be bad. Extensive structural modification would be needed, i.e. 75%

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That is impossible. I'm sure the tests showed that the faceplates were actually invulnerable to penetration.

Impossible is too strong a word, the penetration DID occur. See here. Now, are those likely combat conditions? Probably not, as noted.

Is comparing penetrations and performances at 30,000 yards (roughly 17 miles) useful for naval combat when the record naval combat hit was at about 26,100 yards (a little less than 15 miles)?

Even with radar, I wouldn't imagine battleships actually would hit each other much at all at anything more than 14 miles, and more likely 12 miles. For land targets I can see the longer ranges working (the 44,000 plus yards for the Iowa-class would allow Iowa to shell almost all of San Francisco from where she sits right now).

I'm imagine the Dutch would be thinking in terms of visual combat ranges, since radar is a non-factor in 1930. So how would their typical over-weight shells do compared to their likely opponents in the Pacific?

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Now, are those likely combat conditions? Probably not, as noted.

In the final comments it does note that it is impossible to penetrate under combat conditions, i.e. muzzle not touching plate.

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they had not attempted to make improved face-hardened armor, as the U.S. Navy did during the 1930's

Its fairly amusing that out of the 5, the USN made the 4th best quality armour even after obtaining a sample from Krupp and then "improving" it. As an example the Italian Terni FC plate is c. 20.1% better than the USN plate(Class A). Thats a huge difference.

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So how would their typical over-weight shells do compared to their likely opponents in the Pacific?

Not that bad. The 898kg 381mm shell is a good compromise between mv and shell weight.

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Having a big hole in the armourdeck(which is probably the strength deck) would be bad. Extensive structural modification would be needed, i.e. 75%

I fully agree on that, I wanted to raze it down to the armor deck. This leaves a barbette ring flush with said deck- no new holes, same existing hole, same structure at the strength deck, less wieght above it.


Dutch ranges...
I'm looking at effective ranges out to 24-25,000 yards in this consideration, for deck issues 20-25,000 performance. Around 22,000 yards and a bit over is considered maximum practical range in this case, based on one of the Gangut's class repeated bracketing of either Goeben or Breslau in WWI....which I don't know happened here. Still accuracy in these ranges is conceivable.
Anyhow, I am presuming enemy decks to be 12-15cm. IF the larger weapon would allow penetration over these thresholds in these ranges and the 345mm didn't, then it becomes a superior alternative.

However, first I need to establish if upgunning to 36cm is even an option. IF it's an option- is there a limit on the shell dimensions, and what that may be. Then I can evaluate the comparative advantages or lack of same