Plunging fire and historical armour values.

[Draco]

Okay first off I am no expert on naval gunnery or naval armour. I've already seen multiple people here on the forums display levels of understanding that go far beyond my own, but the issue must be raised and I have seen no one else do so fully yet, so here goes.

We need to talk about plunging fire.

Historically, ship designers operated within a system known as zone of immunity, or IZ for short. To put IZ in the simplest of terms, a ship's vertical armour (the belt) would be specifically made to resist all shells of a certain calibre up to a certain range and beyond, fx. the Iowa class was designed with a 12.7" belt which was designed to resist 16"/45cal gunfire at ranges exceeding 18,000m, giving her an "inner" zone of immunity limit of 18,000m.
In contrast to this, the deck armour would be designed to resist gunfire at certain ranges and below. Again using the Iowa, this would be a 6" main deck plate covered by a 1.5" 'fuze-deck', which was specifically there to set off a given shell's fuze and have it explode before or on contact with the main 6" deck. This 6+1.5" deck theoretically gave her an IZ of 30000m and below against the 16"/45cal. An interesting sidenote here is that this IZ is calculated for the guns of her predecessor the South Dakota class, since for a large part of the design process these were the guns she was expected to carry, and so in contrast to most ships, the Iowa does not actually have an IZ against her own guns readily available, which would otherwise be the norm... but I digress.

What's important to take away from this is that a given belt thickness renders you immune to direct fire at a certain range and beyond, whilst deck armour gives you immunity from plunging fire at a certain range and below.
The space between your belt's immunity and your deck's immunity is your overall zone of immunity, where neither direct nor plunging fire can penetrate the deck or the belt of your citadel and cause catastrophic damage.
You can still take superficial damage of course, but your vitals will remain untouched.

What amazed me so much when I began playing this game was that for the most part, this system seemed to be the the core functional armour mechanic in use in game.
Give a ship enough belt armour and it becomes immune to direct fire.
Give it enough deck armour and it becomes immune to plunging fire.
Excellent!
But I've been playing for a while now, and have read up a lot on actual armour values from real ships as I played, and it quickly began to strike me just how disproportionately heavy you had to make your deck plates before the desired immunity zone was achieved.
Again with the Iowa example, 7.5" total seemed adequate up until the very limits of realistic spotting capabilities, yet if I replicate this in game, even a twelve incher will go right through that at combat ranges going all the way down to 20000m. This unsettled the historical accuracy enthusiast within me, and so I began to run some tests.

First, I took things to the extreme.

I observed that most naval designers IRL went for a IZ of between slightly under 20000m all the way up to 30000m, and decided to use this as my main parameters for testing.

So with that in mind, how thick a deck would you need to create a plunging fire zone of immunity up to 30000m for the biggest guns in the entire game, the mighty 20" with super-heavy shells. Thankfully, the game tells us! Thx devs!

So the first image at the bottom of this post is the armour pen data for the 20" Mk.III (latest available) with super-heavy shells (tube powder). As you can see at 30000m it penetrates a whopping 60.1" of total deck armour equivalent.

 by applying the max allowed bonuses to our armour in game, we can bring it up to a 118% increase by equipping both krupp IV and all-or-nothing armour on our ship.

This leaves us with 60.1/218%=27.5" of real deck armour. Mind you the turret face of the Yamato was only 26", and that was designed to resist 18" guns at point blank range... so a number above this must surely be far off... yet when I tested it, it bore true.
You literally need to put 27.5 inches of deck armour on your ship to resist these shells at 30000m in the game...

So there goes the first bit of realism straight out the window, and let me show you why.

Let's step away from the Iowa for a second and instead go with the Montana, since she was in fact (and in contrast to her predecessor) rated with an IZ against her own guns, the 16"/50cal Mk.VII.
According to wikipedia her belt would have been 16.1" and her decks 2.25" upper and a 7.35" main deck in the same fuze activation arrangement as the Iowas, and contemporary engineers concluded that this gave her an immunity zone between 18000m and 31000m against the improved firepower of her 16"/50cals.

Now compare this real world data to my experiment. 2.25+7.35 inches of deck armour (a total of 9.6 inches) could resist 16" super-heavy shells at 31000m.
In game however, a 20" SH shell requires 27.5" to stop.
That's a threefold increase on the part of the armour required, but only a 1.75 fold increase in shell weight (1928kg vs 3418kg on the 16" and 20" respectively).

Let's now scale the experiment down to match the montana's characteristics,  by taking the 9.6" figure, running it through the 218% amplification and netting your 20.9" of effective thickness and testing it against the 16" SH shells available in game, you find that it only resists plunging fire from around 18000m and below (rated at 19.3" equivalent pen at 17500m)
Which means that if you made the Montana in-game, her zone of immunity would be between 18000m and... well... 18000m. In effect there now is no zone of immunity at all, since plunging fire in-game is somehow just extremely overpowered compared to real life, to the point where an armour protection rated for 31000m doesn't even start to become effective in-game before 18000m, almost half, and incidentaly also almost the exact range where her belt armour would cease to be effective IRL.

This is of course very disappointing. The game handles extremely well and feels very realistic in close quarters engagements between cruisers and destroyers, but once you scale it up to battleship sizes the lack of realism on the part of long range gunnery and penetration values just straight up breaks it for me. But being the pathologic guy that I am I decided not to bother and simply up my deck armour to the point where it would artificially create the desired zone of immunity effects, with hilarious results in hidsight.

I started regularly designing my battleships with, say, a 14" belt but a 16" deck to achieve the armour protection and IZ of for example the King George V, but then the patches giving severe weight penalties on bulkheads came along and I had to sacrifice more and more vital design features to keep my decks artificially efficient, to the point where my ships had no rudder upgrades, no turret rotation upgrades, barely any torpedo protection, not a single secondary gun and literally 0" of armour on the belt and deck extended, whilst still costing two to three times as much as their historical counterparts both in money spent and weight required.
All this of course always fell flat as soon as these designs came up against something like an H class, whose 20" guns still required those ridiculous 27.5" of deck armour to survive at combat ranges.

But then during my recent tests after patch 11 I noticed something.
I was having a fight with a 15" armed battleship in my own battleship equipped with 14.5" of deck armour, and right around where I calculated that my deck armour would start to become sufficient against that armament, I noticed that shells where hitting my deck and giving me the "penetration" counter, but the damage incurred would be almost comparable to an over-pen. Instead of 90 dmg, I got around 20 dmg, and I immediately likened this to a shell penetrating the upper fuze deck to explode against the main deck, causing limited damage as compared with a "full" penetration.
I don't know if this is intentional, but regardless I must highly encourage it.
This perfectly simulates the kind of damage a battleship with a separate fuze and main deck would incur at combat ranges. Still enough to be significant, but not enough to be fatal, and this is exactly the kind of protection such armoured decks would have allowed for. The shell still detonates inside the ship, but outside the citadel, causing only moderate damage.
Perfect!
Now make this universal.
Make it the norm, rather than a freak incident that only becomes apparent after 20 test runs. Any hit on a main deck of 8" or thereabout should produce this kind of damage below 30000m, and there should optimally also be choice between going for a single thicker deck plate which might deflect all shells, but which in turn takes all the damage if indeed penetrated, and instead choosing two separate decks which only limit the damage done above the second deck at certain ranges.

Secondly, we also need to talk about bulkheads (again).

My main issue with bulkheads isn't that they're too heavy or too light, my main issue has to do with simple physics.

I ran some more tests, and it appears that a battleship of 109000t displacement has about a 90% chance of receiving over-pens rather than actual pens on unarmoured sections of the hull with max bulkheads, meaning that when a battleship grade gun hits the extended deck (which for test purposes was left on 0" thickness) the shell goes right through and does next to nothing.

If this experiment is then repeated on a ship with low bulkheads (anything from many to minimum) the shell almost always penetrates and does full damage.

I find this confusing.

Logically, the less bulkheads you have in the way, the higher the chance of over-pens, because once a shell strikes a bulkhead, it tends to detonate, since those are heavily armoured, often as heavily as the main belt of the ship in question.

Instead what we get is the lower the bulkhead setting, the higher the chance of shell detonation as opposed to over-pens.

Again, what am I missing here?

Shouldn't a hull saturated with heavy and numerous bulkheads be more rather than less susceptible to in-ship detonations on unarmoured sections of the ship?

Again I'm not a naval designer so if I'm coming off as a rough plebeian who doesn't know what he's talking about then please put me in my place and tell me why, it just doesn't seem logical from where I'm at.

I find it especially problematic since with the above mentioned mechanics of bulkheads in relation to pen-over-pen dynamics, maximum bulkheads are essentially a necessity that you cannot in good faith downgrade on and still consider your ship competitive. They are now extremely heavy to field on your ships for sure, but the current mechanics surrounding them still makes them an absolute must, and so I find that all my designs are now exercises in how to still make a semi-competent ship around the key feature that is maximum bulkheads, sacrificing everything from firepower to speed to armour (especially deck armour) to keep this essential feature, often ending up with ships that are twice or thrice as heavy and expensive as the ship I'm trying to replicate, either because I had to give it triple it's historical deck armour to give it a similar long range protection characteristic to what it historically had, or by simply sacrifing the extended armour entirely and hoping for maximum bulkheads to give me those over-pens rather than full-pens.

So I was wondering, will this be adressed at some point? Is it intentional that deck armour is currently two to three times less efficient than it was historically? Is there a counter to this that I am just not aware of? Are bulkheads just going to be continually nerfed in terms of weight penalties rather than looking at some of the real-life advantages that might come with low bulkhead settings and using them to give lower bulkheads an actual pro in regards to max?

Finally I'd like to give you my current example of a semi-competitive 1940s era battleship, to really ram home the point.
The second picture below is my current build, my current design for a US super-Iowa.

maximum bulkheads, long range, maximum displacement (109000t or about two yamatos worth) and 30 knots of speed.

This baby costs a whopping 236000000$, or 2.3 regular iowas, has zero rudder or turret rotation upgrades because I couldn't spare the weight, also has only a double bottom and lvl 1 torp protection because that isn't important enough either, meaning that it actually has far worse underwater protection than the Iowa herself (3 torp bulkheads, equivalent to lvl 3 protection in game, and a tripple hull bottom). However I'd rather forego it and just keep them completely out of torp range if it buys me a bit of extra long-range protection with the way the game works right now.
extended belt and deck are both literally left at 0", which is actually quite historical, but logically shouldn't work with maximum bulkheads, yet somehow it does.
She also sports 14.4" of deck armour, which is completely inadequate given the current game mechanics but it was the best I could do, and it will only protect her from her own armament inside of 20000m, giving her an extremely narrow zone of immunity of just 3000m, between roughly 17000 and 20000m once her 14" belt is accounted for.
Notice that the deck is heavier than the belt. It is so on all my ships of above cruiser size.
The only part of her armour that is adequate within the current mechanics of the game is her turret top armour, which I was able to bop up to 21.4", giving her immunity from direct turrent hits from her own guns up to 27000m and below, which at least begins to seem sufficient from a designer's point of view, though still not ideal, even if you disregard the fact that historical battleships usually made do with less than 10" of top turret armour. Meanwhile, her turret front could be reduced all the way down to 18", again giving her immunity from her own guns up to around 9500m, which is actually more than necessary and I might consider giving her a 16" or even 14" turret face instead to give her more deck and turret top protection to bring her closer to a historical result in terms of effective IZ.

This example should make it blatantly clear why the current design parameters are not very realistic.
A ship that is theoretically not only capable of but specifically designed for fighting at 20000-30000m currently requires much heavier deck than belt armour to enable it to fight at it's own designated combat ranges, and this is true across all the nations (I find it especially enfuriating to contemplate that german ships of 130000t disp. still cannot hope to equip enough deck armour to give them reasonable zones of immunity even against 18" guns, much less 20"ers).

Thus I sincerely hope that deck armour will be addressed in the next patch, and made much more effective than it currently is, and that some thought be put into making maximum bulkheads have some drawback to incentivize people to avoid them, rather than just making them prohibitively heavy and expensive to equip, which doesn't really balance things but just makes all other aspects of the design process more aggravating. because you absolutely still have to have max bulkheads anyway, until some balance is introduced that is, possibly in relation to the max-min pen-over-pen dynamics I outlined above.

Thanks for reading, and keep up the good work devs, still an amazing product you're developing in spite of it's flaws.

Edited March 5, 2021 by Draco
spelling functionally as fucntionally

[madham82]

For refence can you post the 16" Mk 3 gun table? Here is the data on navweps for comparison. One issue to address first is I believe the Devs stated the values in game are for iron armor (not contemporary armor like used for the table below). So we will need to calculate that first to know how are off. But one thing that is clear regardless, at NO  point is the deck armor pen values close to side armor. For example at 30K meters, the side pen value is the same deck pen value at max gun range. Meanwhile looking at the game values, at 30K meters the side pen value is way lower than deck pen at the same range. Clear indication of bad values. That's something iron or steel baseline values won't change. 

Range	Side Armor	Deck Armor	Striking Velocity	Angle of Fall
0 yards (0 m)	32.62" (829 mm)	---	2,500 fps (762 mps)	0
5,000 yards (4,572 m)	29.39" (747 mm)	0.67" (17 mm)	2,280 fps (695 mps)	2.5
10,000 yards (9,144 m)	26.16" (664 mm)	1.71" (43 mm)	2,074 fps (632 mps)	5.7
15,000 yards (13,716 m)	23.04" (585 mm)	2.79" (71 mm)	1,893 fps (577 mps)	9.8
20,000 yards (18,288 m)	20.04" (509 mm)	3.90" (99 mm)	1,740 fps (530 mps)	14.9
25,000 yards (22,860 m)	17.36" (441 mm)	5.17" (131 mm)	1,632 fps (497 mps)	21.1
30,000 yards (27,432 m)	14.97" (380 mm)	6.65" (169 mm)	1,567 fps (478 mps)	28.25
35,000 yards (32,004 m)	12.97" (329 mm)	8.48" (215 mm)	1,556 fps (474 mps)	36.27
40,000 yards (36,576 m)	11.02" (280 mm)	11.26" (286 mm)	1,607 fps (490 mps)	45.47
42,345 yards (38,720 m)	9.51" (241 mm)	14.05" (357 mm)	1,686 fps (514 mps)	53.25

source: http://www.navweaps.com/Weapons/WNUS_16-50_mk7.php

Edited March 5, 2021 by madham82

[Draco]

sure, here's the ingame 16" Mk.III with SH shells and tube powder propellant.

Seems quite different from your graph. Deck pen is consistently higher than IRL.

[Draco]

Unfortunately game settings do not allow me to display it in yards, but they're pretty close to meters anyway.

[Draco]

@madham82 is your data rated against class A, B or STS steel plating? Maybe I can snoop around a bit and find out what the various "krupp this, krupp that" armour upgrades are supposed to represent so we can get closer to the real story.

Edited March 5, 2021 by Draco

[madham82]

6 minutes ago, Draco said:

@madham82 is your data rated against class A, B or STS steel plating? Maybe I can snoop around a bit and find out what the various "krupp this, krupp that" armour upgrades are supposed to represent so we can get closer to the real story.

It looks like it works on iron or steel (which begs the question what kind of steel would be equal to iron, or was another variable used to proof steel). Here's what I found for those that have time to read and confirm.

http://www.navweaps.com/index_nathan/Hstfrmla.php

[Draco]

well the game uses wrought iron plating as it's baseline armour level in the order displayed in the screenshot, and as far as I can read up on, krupp II is face hardened, whilst krupp III is a combination of face hardened and homogenous krupp steel distributed in such a way that extra homogenous plates would support the face hardened krupp plates, allowing for less of these more expensive plates to be used whilst still providing the same effective ductile mass behind them.
This is the exact description you will find on the wikipedia page of the Iowa class under the armour section.
I have no idea what krupp IV means, as it just says "new and improved" in it's description, but disregarding that we can assume that the Iowa used krupp III in relation to how this game frames it and then look at wether a 90% increase in effective thickness is what you'd get from the armour on Iowa when compared to a regular iron plate as used on fx. the HMS Warrior.
Regardless of wether a 90% increase in effective thickness is the real world case however, I think it already stands clear from the navweaps graph that armour pen to the sides and top respectively should converge around 35000-36000m or 40K yards as it does in the graph and indeed in real life. That basic principle of physics does not rely on armour thickness, but on shell velocity and angle of impact.
Instead, we find that in the game these values converge just before 20K meters as seen in my screenshot, almost 15K meters off from where they should IRL in the vast the favour of deck penetrations.

Edited March 5, 2021 by Draco

[madham82]

Yea I agree, the "actual" values are irrelevant since the game will have to use it's own. But the trend on the charts clearly shows real world shells deck pen values would never exceed side armor values except at max range. In addition the convergence would also only occur near max range, completely opposite of the game values (which looks closer to mid range in game). 

@Nick Thomadis can you take a look at this with the team. This will drastically change ship designs (at least players) as it will make immunity zones possible, and therefore change gameplay significantly (ships will have to close the range to be effective). We can post more real world tables for comparison, but I'm sure the story will be the same due to physics. So in the game examples shared (20" and 16"), the max deck pen value would be close to the side armor pen value at max range. Something like this:

16": 25K meters - 14.4"/15", 0.5%

20": 35K meters - 15.8"/16.4", 0.5%

 

[Draco]

Thank you @madham82 , if implemented, this will improve the game so much ❤️

Edited March 5, 2021 by Draco

[Cpt.Hissy]

Just checked something. Regardless of shell type, deck pen overcomes side pen in between 17km and just below 20 km for all guns from 2" up to 17", except smaller guns have max range below this convergence point.
And between 15km and 17.5km for 18"-20"

There is something very wrong in these numbers altogether.
 

[Nick Thomadis]

In those calculations is is not included the actual angle of fall for the shells that hit. They are indicative max. penetration values for the given ranges. The penetration applied is always depended on the very special conditions of the ships involved and the ballistics of the shells at the moment of impact.

You can see the actual penetration values when you observe the identified target by hovering the cursor on it.

[disc]

3 hours ago, Nick Thomadis said:

In those calculations is is not included the actual angle of fall for the shells that hit. They are indicative max. penetration values for the given ranges. The penetration applied is always depended on the very special conditions of the ships involved and the ballistics of the shells at the moment of impact.

You can see the actual penetration values when you observe the identified target by hovering the cursor on it.

I have a little difficulty interpreting this. Does this imply that the "max penetration" is the theoretical pen of a shell that impacts at a perfectly normal angle, at 90 degrees, no matter the range? If so, is this based on devolving the impact vector in x, y, and z components, or is something else going on?

[Cpt.Hissy]

I don't get it either. If it's angle-independed penetration value, why there's two of them?
All the difference between deck and side pen values is based solely on the different angles of deck and side, namely that the deck is horizontal and side is vertical. A shell itself just punches through whatever it hits with one single force, regardless of how said whatever is called...

Edited March 7, 2021 by Cpt.Hissy

[Nick Thomadis]

3 hours ago, disc said:

I have a little difficulty interpreting this. Does this imply that the "max penetration" is the theoretical pen of a shell that impacts at a perfectly normal angle, at 90 degrees, no matter the range? If so, is this based on devolving the impact vector in x, y, and z components, or is something else going on?

Yes, it is the theoretical pen of shell at max. effective angle, supposing that it hits the target always at a right angle. In combat, we also use the angle of impact and armor of target to get the actual penetration calculation, which is always smaller than those theoretical values, due to the angle of hit.

Statistically, it can be improved later, to give more meaningful data for player, according to gun (knowing an average angle of fall due to the gun ballistics) but currently this is not happening, so some players use this data as full representation of what is occurring in combat, which is wrong. 

[madham82]

I'm still a bit perplexed at this, namely because the in game pen value popup doesn't work until you have fully ID'd the ship, and only works when viewing from your ship and getting the mouse on the enemy. This is far too clunky to use and also doesn't work at long range consistently (I have a screen showing me shooting at the target but can't see it on the horizon from my ship). 

So I ran a test and grabbed some screens. Please help me interpret this:

Gun table as built in designer (using 16" for rough comparison to ballistics of the US one):

Pen popup (note the range and values for side/deck):

Armor breakdown for the target:

So the question, why if the values are theoretical max am I seeing almost the exact same values on the gun table and pen popup? Perhaps because we are almost sailing broadside to each other for the most part, but that just goes back in a way to the original thinking behind this thread. Deck pen values are too high in comparison to side pen. Not the actual values, but the trend of deck pen vs side pen on the table. Only at near max range should the deck pen value be actually greater than side pen at that same range. Right now the tables are skewed such that plunging shells have pen values similar or greater to side pen too soon. That's not physically possible. For example:

In game, the 16" mk3 starts exceeding side pen values at 20K meters with it's max range of 30K meters. That's a 10K meter spread when in comparison to the real world 16" is only about 2K meters. That's exactly the thinking behind immunity zones. The Iowa could stay out of that danger zone and it's deck armor would stop plunging shells but keep enough distance to prevent shots from landing horizontal to the belt. 

Now with that said, this could simply be just the way the data is presented and not how it is being handled by the game. I've not seen enough evidence to show that indeed those plunging shells are getting through like the data portrays. Hence mine and other's confusion. 

If I could make one suggestion, get rid of the popup functionality of the pen display in battle. Make it a fixed data tab somewhere that displays values when you are actually locked on to a target. This would be a big QoL improvement IMO. 

Edited March 8, 2021 by madham82

[o Barão]

3 minutes ago, madham82 said:

I'm still a bit perplexed at this, namely because the in game pen value popup doesn't work until you have fully ID'd the ship, and only works when viewing from your ship and getting the mouse on the enemy. This is far too clunky to use and also doesn't work at long range consistently (I have a screen showing me shooting at the target but can't see it on the horizon from my ship). 

So I ran a test and grabbed some screens. Please help me interpret this:

Gun table as built in designer (using 16" for rough comparison to ballistics of the US one):

[url=https://flic.kr/p/2kHWnNv][img]https://live.staticflickr.com/65535/51014056861_5c984aa900.jpg[/img][/url][url=https://flic.kr/p/2kHWnNv]gun table 2[/url] by [url=https://www.flickr.com/photos/135635256@N06/]Tim Hamilton[/url], on Flickr

Pen popup (note the range and values for side/deck):

<a data-flickr-embed="true" href="https://www.flickr.com/photos/135635256@N06/51014147232/in/dateposted-public/" title="IZtest1"><img src="https://live.staticflickr.com/65535/51014147232_850968ed1e.jpg" width="500" height="281" alt="IZtest1"></a><script async src="//embedr.flickr.com/assets/client-code.js" charset="utf-8"></script>

Armor breakdown for the target:

<a data-flickr-embed="true" href="https://www.flickr.com/photos/135635256@N06/51013333943/in/dateposted-public/" title="IZtest2"><img src="https://live.staticflickr.com/65535/51013333943_8bd1a01281.jpg" width="500" height="281" alt="IZtest2"></a><script async src="//embedr.flickr.com/assets/client-code.js" charset="utf-8"></script>

So the question, why if the values are theoretical max am I seeing the exact same values on the gun table? Perhaps because we are sailing broadside to each other for the most part, but that just goes back in a way to the original thinking behind this thread. Deck pen values are too high in comparison to side pen. Not the actual values, but the trend of deck pen vs side pen on the table. Only at near max range should the deck pen value be actually greater than side pen at that same range. Right now the tables are skewed such that plunging shells have pen values similar or greater to side pen too soon. That's not physically possible. For example:

In game, the 16" mk3 starts exceeding side pen values at 20K meters with it's max range of 30K meters. That's a 10K meter spread when in comparison to the real world 16" is only about 2K meters. That's exactly the thinking behind immunity zones. The Iowa could stay out of that danger zone and it's deck armor would stop plunging shells but keep enough distance to prevent shots from landing horizontal to the belt. 

Now with that said, this could simply be just the way the data is presented and not how it is being handled by the game. I've not seen enough evidence to show that indeed those plunging shells are getting through like the data portrays. Hence mine and other's confusion. 

If I could make one suggestion, get rid of the popup functionality of the pen display in battle. Make it a fixed data tab somewhere that displays values when you are actually locked on to a target. This would be a big QoL improvement IMO. 

 

I had some problems using the links you posted but it seems that you didn't hover the target. You need to hover the target in the screen not in the panel. It will show the angle, the % in hitting the deck or belt , etc. However i am still trying to understand how the values work.

[madham82]

1 hour ago, o Barão said:

 

I had some problems using the links you posted but it seems that you didn't hover the target. You need to hover the target in the screen not in the panel. It will show the angle, the % in hitting the deck or belt , etc. However i am still trying to understand how the values work.

Right the 2nd screenshot shows the popup in the top towards the right. Yea I need some help in how to read those values too. 

[Draco]

@Nick Thomadis We understand that further modifiers are being applied.

This is not the issue.

The issue is that belt vs deck pen in general should converge around the maximum range of each gun type in order to be realistic.

This means that if a given gun can shoot 30km, deck pen chance should only overtake belt pen at around 28-29km, regardless of modifiers.

Currently the values converge around 17-20K meters regardless of a given gun's max range, making deck protection in-game far weaker than IRL and preventing usage of the IZ system of protection unless you make your deck thickness significantly greater than your belt thickness, which is ahistorical and unrealistic.

You can't fix an incorrect formula by multiplying it with a correct one, and thus this discussion has nothing to do with the angle of impact modifier and everything to do with the incorrect base values.

IRL battleships would have to close the range for their GUNS to become effective, but as it stands you currently have to close the range to make your ARMOUR become effective.

The HMS Hood was the exception to this rule, but right now the game plays as if all battleships are HMS Hoods regardless of wether you actually armoured them properly on the deck.

Also, deck pen chance is not visualized when you hover over a given ship as you said, only the belt pen, since the displayed schematic is viewed from the sides only where the deck cannot be seen.

Edited March 8, 2021 by Draco

[Draco]

Unless of course this little sliver of green is supposed to repressent the deck armour
in which case A: why isn't it representing the upper belt like it would IRL, and
B: great, we now have visual confirmation that the game is unrealistic and that the problem must be adressed. 

Edited March 8, 2021 by Draco

[Draco]

To showcase what I mean, here's an actual Iowa class in game (she's 30K tonnes overweight and is missing a few upgrades like turret rotation, but her armour and main guns match the original so let's ignore the weight issues for now)

IRL her deck would defend her against her own guns up to 30K meters.
IG her deck defends her against her own guns up to ca. 16K meters if the chart below is followed, which bears true when tested in-game.

To prove it, here are some screenshots of her being penned by various guns that should have no realistic chance of hurting her with deck pens at their range.

Here's a mid deck pen by a 17"er at 16.6km range, this gun should have no chance of penning her deck below 28K using real world math.

Here's one by an 18"er incurred at 20.8K distance. Although powerful, this shell's real life counterpart would still have been absorbed by the deck armour 6 kilometers ago, yet IG deck armour is useless, and so it penetrates anyway.

Finally here's one of her taking a mid deck pen from a 15" Mk.I (first tier) gun firing light shells at 19K distance. This gun should be incapable of penetrating her deck at ANY distance that the gun is capable of ranging out to, yet it goes right through regardless.


Did that specify the problem more clearly?

Edited March 8, 2021 by Draco

[Draco]

BTW mid deck in this instance was 7.5" like IRL.

[SPANISH_AVENGER]

3 hours ago, Draco said:

To showcase what I mean, here's an actual Iowa class in game (she's 30K tonnes overweight and is missing a few upgrades like turret rotation, but her armour and main guns match the original so let's ignore the weight issues for now)

IRL her deck would defend her against her own guns up to 30K meters.
IG her deck defends her against her own guns up to ca. 16K meters if the chart below is followed, which bears true when tested in-game.

To prove it, here are some screenshots of her being penned by various guns that should have no realistic chance of hurting her with deck pens at their range.

Here's a mid deck pen by a 17"er at 16.6km range, this gun should have no chance of penning her deck below 28K using real world math.

Here's one by an 18"er incurred at 20.8K distance. Although powerful, this shell's real life counterpart would still have been absorbed by the deck armour 6 kilometers ago, yet IG deck armour is useless, and so it penetrates anyway.

Finally here's one of her taking a mid deck pen from a 15" Mk.I (first tier) gun firing light shells at 19K distance. This gun should be incapable of penetrating her deck at ANY distance that the gun is capable of ranging out to, yet it goes right through regardless.


Did that specify the problem more clearly?

Yeah. In short: deck armor is currently useless.

[Tycondero]

Yes, deck armor penetration values should be brought in line with historical data, meaning that we need to lower deck armor penetration overall. Currently, BBs feel very weak at distance when hit, eventhough roughly historical thickness is applied to the design. If this means we need to rebalance weight values elsewhere, I would recommend making the engines more heavy so that also BB speed comes down a bit.

[Bigjku]

1 hour ago, Tycondero said:

Yes, deck armor penetration values should be brought in line with historical data, meaning that we need to lower deck armor penetration overall. Currently, BBs feel very weak at distance when hit, eventhough roughly historical thickness is applied to the design. If this means we need to rebalance weight values elsewhere, I would recommend making the engines more heavy so that also BB speed comes down a bit.

Speed needs to be dealt with with SHP caps in the machinery types.  That would solve that problem in the most accurate way.

As far as plunging fire I agree.  Hits from a distance tend to do too much damage or not enough.  Sounds odd right?  I think deck hits should be effective only at certain ranges as described but if you get through the deck you much more likely to do high end damage because of the trajectory.  You will end up deep in the ship near shafts, magazines and the keel.  So it should be harder to penetrate than it is but the rewards for doing so should be greater.

Developing the specialty gear to reliably try to do this was a multi decade investment by most navies that really tried at it.

[Cpt.Hissy]

 A question regarding SHP caps. It's due to hydrodynamics based upper limit on size and rotation speed of the screws, right? That seems to be quite flexible actually, especially in smaller than ultrahuge ships.
Anyway, this limit isn't directly tied to SHP, so that'll be arbitrary cap, and that doesn't usually work well in games. Maybe have some alternative?

Regarding plunging fire, nobody finds it strange that ALL guns actually have nearly identical pen curves? Aren't lighter shells supposed to loose energy faster, have steeper arching trajectories, and therefore have penetration in general drop faster and have that spot where horizontal pen overcomes vertical pen at closer ranges?
This was the main reasoning behind going bigger in earlier years as i remember. For big gun's flatter trajectory and greater distance of effective penetration.
  If i don't understand something in artillery ballistics, please correct me, but i think this one part i understand correctly...