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question about main gun penetration


Russell

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when I use huge gun such as 18", paper penetration are always nice, even use semi-ballistic ap(penetration better than semi-ap less than standard ap) at 25-30km it has 60-80'' penetration over deck, way much beyond enemy possible armor. But when in a fight, ap hit enemy battleship deck at 25-30km, it always shows partial-pen, why? Under which condition can ap penetrate battleship and make devastating damage? Should I use standard ap to increase penetration or use semi-ap to increase damage? On paper, even semi-ap penetration is enough.

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4 hours ago, Russell said:

when I use huge gun such as 18", paper penetration are always nice, even use semi-ballistic ap(penetration better than semi-ap less than standard ap) at 25-30km it has 60-80'' penetration over deck, way much beyond enemy possible armor. But when in a fight, ap hit enemy battleship deck at 25-30km, it always shows partial-pen, why? Under which condition can ap penetrate battleship and make devastating damage? Should I use standard ap to increase penetration or use semi-ap to increase damage? On paper, even semi-ap penetration is enough.

The thing is, even higher-end AP rounds won't be enough- partial pens are all you can really hope for with even the highest AP types. Once you hit 1930's or so tech in campaign mode, penetrating shell hits are basically a thing of the past against armored ships unless you hit superstructure like funnels or towers or a secondary gun of some kind.

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There are lots of things that influence shell pen and whether or not you get full or partial pens, the major factors being:
>Raw Shell Pen Values (influenced by shell weight, shell type, propellant, gun size and barrel length)
>Ballistics of the Shell (influenced by shell weight, shell type, propellant, gun size and barrel length)
>Armor of the Enemy Target (strength, thickness, any sloping/rounding)
>Angle of Impact

I don't know the specifics of your situation (what barrel length, propellant, shell weight, etc) but, to explain your 25-30km deck hit resulting in a partial pen with an 18" gun that has anywhere from 60-80" of pen in as simple a way as possible:

Going by the values on paper, yes, it should result in a full penetration. Unfortunately, those values reported in the ship designer are for the ideal penetration conditions: your shell impacting flat armor at an angle of basically 90 degrees. You will rarely get those conditions...that's a fact. So, now we look at all the other factors that are influencing that shell hit.

If you are using long-barreled high-velocity guns with heavy or super heavy shells, the shell trajectory becomes flatter at all ranges. Flatter shell trajectories means you will impact the side of the hull (BELT ARMOR) at angles closer to 90 degrees while your shells hit the top of the hull (DECK ARMOR) at angles much less than 90 degrees. So, in layman's terms: unless you are at extremely long range/max gun range...you will rarely see full deck pens against heavily armored targets, purely down to the angle of impact being too steep/shallow, depending on what side you measure from. So once a shell impacts, the game considers your shell's raw penetration values and power, the fuse timer on your shell, angle of impact, armor thickness (accounting for any bonuses from armor quality, citadel choice, resistance values of the hull, etc) and then calculates whether or not your shell penetrates the armor.

Now, let's say that shell did penetrate the deck armor. You still aren't guaranteed a "full pen" because the enemy ship likely has a citadel of some kind. Again, I don't know the specifics of your situation, but let's just say that the enemy ship has Citadel V "all or nothing" armor scheme. Once you penetrate the main deck, you then have 3 more layers to penetrate before you get to the heart of the ship and score a "full penetration." And after each layer you penetrate, your shell loses some of it's penetrative power (if you hover over the citadel armor values for each section in the ship designer, it will tell you exactly how much power is lost after each layer) which means that your shells might penetrate the main deck, but could be stopped by the first, second or third inner deck (each different citadel has different numbers of inner decks and belts). And if you successfully pen the first armor layer you hit (and your shell's fuse timer hasn't burnt down) the game then repeats the method above for calculating whether or not a penetration is scored against the second layer of armor you hit and the process repeats until your shell detonates, a penetration wasn't scored, or your shell goes through the other side of the ship because you over-penetrated the ship. Overpens usually happen when you hit the superstructure or belt/deck extended, or when you are shooting at ships like CLs and DDs.

Another issue that might arise is your shell type. When using semi-armor piercing, you are shortening your fuse timer and sacrificing penetration power for more damage. So in practice, this means there is a potential for the fuse of the shell to burn out before fully penetrating the first armor layer it hits, thus leading to a partial pen. And when the game says there is something like a "-40% ricochet chance" with the semi-armor piercing...that is because the shell doesn't have enough time to ricochet because it explodes to quickly (the opposite is true of "standard" or higher AP shells: the game says they have a "+XX% ricochet chance" but that's just because it has time to ricochet off the armor because the fuse is longer). In general SAP or Semi-Ballistic (maybe even the standard AP shells if your guns aren't too big or too powerful) are best against BCs and CAs when fired from battleships, but of course, if you chose to go with the SAP option on your BB...you might struggle against enemy BBs.

TL; DR Deck pens usually only happen at extremely long range/max gun range, or against lightly armored targets at close range. Regardless of what the numbers/values in the ship designer say...those number are for the best possible conditions, which you will almost never have. Trying to explain everything about the gunnery/penetration mechanics and models takes time and is complex, trying to actually calculate values takes even more time.

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On 10/2/2022 at 11:05 AM, HistoricalAccuracyMan said:

There are lots of things that influence shell pen and whether or not you get full or partial pens, the major factors being:
>Raw Shell Pen Values (influenced by shell weight, shell type, propellant, gun size and barrel length)
>Ballistics of the Shell (influenced by shell weight, shell type, propellant, gun size and barrel length)
>Armor of the Enemy Target (strength, thickness, any sloping/rounding)
>Angle of Impact

I don't know the specifics of your situation (what barrel length, propellant, shell weight, etc) but, to explain your 25-30km deck hit resulting in a partial pen with an 18" gun that has anywhere from 60-80" of pen in as simple a way as possible:

Going by the values on paper, yes, it should result in a full penetration. Unfortunately, those values reported in the ship designer are for the ideal penetration conditions: your shell impacting flat armor at an angle of basically 90 degrees. You will rarely get those conditions...that's a fact. So, now we look at all the other factors that are influencing that shell hit.

If you are using long-barreled high-velocity guns with heavy or super heavy shells, the shell trajectory becomes flatter at all ranges. Flatter shell trajectories means you will impact the side of the hull (BELT ARMOR) at angles closer to 90 degrees while your shells hit the top of the hull (DECK ARMOR) at angles much less than 90 degrees. So, in layman's terms: unless you are at extremely long range/max gun range...you will rarely see full deck pens against heavily armored targets, purely down to the angle of impact being too steep/shallow, depending on what side you measure from. So once a shell impacts, the game considers your shell's raw penetration values and power, the fuse timer on your shell, angle of impact, armor thickness (accounting for any bonuses from armor quality, citadel choice, resistance values of the hull, etc) and then calculates whether or not your shell penetrates the armor.

Now, let's say that shell did penetrate the deck armor. You still aren't guaranteed a "full pen" because the enemy ship likely has a citadel of some kind. Again, I don't know the specifics of your situation, but let's just say that the enemy ship has Citadel V "all or nothing" armor scheme. Once you penetrate the main deck, you then have 3 more layers to penetrate before you get to the heart of the ship and score a "full penetration." And after each layer you penetrate, your shell loses some of it's penetrative power (if you hover over the citadel armor values for each section in the ship designer, it will tell you exactly how much power is lost after each layer) which means that your shells might penetrate the main deck, but could be stopped by the first, second or third inner deck (each different citadel has different numbers of inner decks and belts). And if you successfully pen the first armor layer you hit (and your shell's fuse timer hasn't burnt down) the game then repeats the method above for calculating whether or not a penetration is scored against the second layer of armor you hit and the process repeats until your shell detonates, a penetration wasn't scored, or your shell goes through the other side of the ship because you over-penetrated the ship. Overpens usually happen when you hit the superstructure or belt/deck extended, or when you are shooting at ships like CLs and DDs.

Another issue that might arise is your shell type. When using semi-armor piercing, you are shortening your fuse timer and sacrificing penetration power for more damage. So in practice, this means there is a potential for the fuse of the shell to burn out before fully penetrating the first armor layer it hits, thus leading to a partial pen. And when the game says there is something like a "-40% ricochet chance" with the semi-armor piercing...that is because the shell doesn't have enough time to ricochet because it explodes to quickly (the opposite is true of "standard" or higher AP shells: the game says they have a "+XX% ricochet chance" but that's just because it has time to ricochet off the armor because the fuse is longer). In general SAP or Semi-Ballistic (maybe even the standard AP shells if your guns aren't too big or too powerful) are best against BCs and CAs when fired from battleships, but of course, if you chose to go with the SAP option on your BB...you might struggle against enemy BBs.

TL; DR Deck pens usually only happen at extremely long range/max gun range, or against lightly armored targets at close range. Regardless of what the numbers/values in the ship designer say...those number are for the best possible conditions, which you will almost never have. Trying to explain everything about the gunnery/penetration mechanics and models takes time and is complex, trying to actually calculate values takes even more time.

can i get the graphs and powerpoint slides that came with this lesson? i was late to class i apologise. jk jk i appreciate this response because it give me some points to think about when putting weapons systems on my ship other than just oh hey this is new so im going to put this on thanks! do you happen to have any advice/ tips on how to make a ship that is a good balance of armour and punch?

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Onething to consider is something the US Navy had to deal with the IOWA's could fire further than the North Carolina's and South Dakota's but they flew flatter and wouldn't have penned the deck, as well, and thats 16/45 vs 16/50, the older 16/45 boats where considered better in a ship vs ship engagement only because they'd have been more likly to get deck hits. Maybe bring your 18in length down so instead of say 18/55 its 18/45, that makes for a more ballistic arch, yes you loose range but your more likely for a deck hit at a favorable angle as well.

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12 hours ago, Mundus_Dog said:

can i get the graphs and powerpoint slides that came with this lesson? i was late to class i apologise. jk jk i appreciate this response because it give me some points to think about when putting weapons systems on my ship other than just oh hey this is new so im going to put this on thanks! do you happen to have any advice/ tips on how to make a ship that is a good balance of armour and punch?

As far as balancing armor and firepower...there are many methods/theories that you can follow, but it largely comes down to personal preference, how you plan on using/deploying your ships (i.e. your own personal doctrine) and if you are building a ship as a counter to something.

When it comes to armor, I tend to follow one of two practices:
1) Making my ships immune to their own guns.
It's exactly as it sounds. I look at what armor values my guns can penetrate at the ranges I expect to get into fights. Let's just say for example that I'm expecting my CA with 8.5" guns to get into fights at 7500m or longer. I look at how much armor my guns can pen at that range of 7500m (where the shells would have the most pen because that is the shortest distance I would be fighting at), and then add at least that much armor to the main belt (but sometimes, depending on armor quality and citadel choice, you don't have to add that much because the quality bonus will allow you to get the same effective strength using less armor).

2) Armoring them to counter a specific AI ship, or be excessively tough
This can sometimes be tricky since you don't always know what the AI is gonna throw at you...but here's how I usually do it (again using a CA as an example): I mount the biggest gun available on the hull or I try to replicate the gun(s) the AI uses and set it up to have the best penetration possible (through gun diameter increases, barrel length, shell weight, propellant, bursting charge, etc) and see how much armor it can pen at what I expect to be normal combat range (this is basically to simulate what would happen if the AI brings their high-velocity super guns). I then either write those numbers down so I remember them, or immediately add on armor, and then remove those guns and build out the rest of the ship. The biggest thing about this approach is that you will almost always have to sacrifice something: whether it be speed, firepower, armor or higher-grade components (like RDF or Aux Engines) to make your ship not be overweight. I usually sacrifice some armor first because, usually, the AI doesn't bring the same exact guns I tested, so I don't necessarily need that much armor. Or, I sacrifice a bit of speed and just keep the armor and make my ships slower, but remarkably tough and resilient. Citadel type and Armor Quality also have an effect here.

Now, the great equalizer with both of these methods is research...both yours and the enemy's. Whoever has the greater tech usually has the better ship (I say usually because the AI can still make some weird-ass designs, regardless of what their tech level is). The two methods I use are also just two of probably many design philosophies you can use. It again just comes down to personal preference and what exactly you want to build/do with your ships.

When it comes to firepower...it again comes down to personal preference, tech levels and some hulls/towers that restrict gun sizes. With the upcoming patch introducing "defects" with ship construction/components, it might not necessarily be the best option to go with the "latest and greatest" tech you unlocked since the "defects" aspect is supposed to represent the dangers of using untested or brand new tech (so maybe you want to hold onto those older 14 inchers for just a while until your new 16 inchers are working smoothly).

When it comes to my BBs, I would say that the 14-16" guns are probably your most cost-effective options. Anything smaller than 14 usually doesn't pose much of a threat against BBs (but can annihilate cruisers), and anything bigger than 16 usually has too long of a reload to be very useful, not to mention being very heavy and requiring some of the biggest hulls in the game. I also try to follow a "gun vs time era" design process where after a certain year...I stop using a certain size gun on BBs because they are either obsolete or outmatched (it loosely follows historical examples).
1890-1900: 10-12" guns
1900-1920: 12-14" guns
Mid-Late 20s: 16" if available, nothing smaller than 14"
1930-1940: Nothing smaller than 16's if I can help it

Again, tech levels will limit your choices and their effectiveness here. And while this is (mostly) arbitrary and just my personal methodology, 10 inch guns are quickly outclassed once you get to actual dreadnought hulls--and by that time, you usually have larger gun options anyways. 12 inchers might be the "most accurate" guns available, but into the mid to late 1910s (so essentially the years WWI was going on), 14 inch guns are usually the new standard. Once you unlock 16 inch guns, you should probably never go back to guns smaller than those...because the AI likely won't go smaller, and will usually have at least one ship class that goes larger than that if you haven't completely bankrupted them. Now, all of what I just said could be rendered null and void by research and tech levels. If your main enemy only has Harvey armor in the late 1910s and you can somehow get good enough penetration values...maybe your 12 inch guns will still be good enough. Your enemy decided to go thin on the armor so your 16 inchers only over-penetrate? Maybe your ships with 14 inch guns are your better option for dealing with them, or maybe just swapping your 16" shells to a lower-penetration option would work (idk why you have to go through and entire refit/retrofit process just to swap shell types but whatever).

With your other ships, it is more or less the same as above...but the choices come down to more of a "what do I want these ships to do" basis rather than a "what is the best gun available" basis. BCs have access to BB size guns on bigger CA hulls and usually hunt cruisers, most CAs will have guns around 8", most CLs will have guns around 6" and most DDs will have guns around 4" or 5".

So, in closing...a lot of this is very arbitrary, varies from person to person, and largely comes down to your own personal preference and how you want to use the ships you build. I've built DDs with 6x2 5.5" guns that wound up being a DD and CL's worst nightmare, and I've built CAs that are high-speed rapid-fire gunboats (the largest gun was 7", then it was packed to the gills with 2-4" secondary guns and it was used to terrorize convoys and DDs).

You can (mostly) build what you want, how you want it...but what would make a "balanced" or "good ship" when it comes to armor and firepower is largely dependent on what exactly your enemy is throwing at you, and what tech you have available to work with.

Edited by HistoricalAccuracyMan
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11 hours ago, HistoricalAccuracyMan said:

As far as balancing armor and firepower...there are many methods/theories that you can follow, but it largely comes down to personal preference, how you plan on using/deploying your ships (i.e. your own personal doctrine) and if you are building a ship as a counter to something.

When it comes to armor, I tend to follow one of two practices:
1) Making my ships immune to their own guns.
It's exactly as it sounds. I look at what armor values my guns can penetrate at the ranges I expect to get into fights. Let's just say for example that I'm expecting my CA with 8.5" guns to get into fights at 7500m or longer. I look at how much armor my guns can pen at that range of 7500m (where the shells would have the most pen because that is the shortest distance I would be fighting at), and then add at least that much armor to the main belt (but sometimes, depending on armor quality and citadel choice, you don't have to add that much because the quality bonus will allow you to get the same effective strength using less armor).

2) Armoring them to counter a specific AI ship, or be excessively tough
This can sometimes be tricky since you don't always know what the AI is gonna throw at you...but here's how I usually do it (again using a CA as an example): I mount the biggest gun available on the hull or I try to replicate the gun(s) the AI uses and set it up to have the best penetration possible (through gun diameter increases, barrel length, shell weight, propellant, bursting charge, etc) and see how much armor it can pen at what I expect to be normal combat range (this is basically to simulate what would happen if the AI brings their high-velocity super guns). I then either write those numbers down so I remember them, or immediately add on armor, and then remove those guns and build out the rest of the ship. The biggest thing about this approach is that you will almost always have to sacrifice something: whether it be speed, firepower, armor or higher-grade components (like RDF or Aux Engines) to make your ship not be overweight. I usually sacrifice some armor first because, usually, the AI doesn't bring the same exact guns I tested, so I don't necessarily need that much armor. Or, I sacrifice a bit of speed and just keep the armor and make my ships slower, but remarkably tough and resilient. Citadel type and Armor Quality also have an effect here.

Now, the great equalizer with both of these methods is research...both yours and the enemy's. Whoever has the greater tech usually has the better ship (I say usually because the AI can still make some weird-ass designs, regardless of what their tech level is). The two methods I use are also just two of probably many design philosophies you can use. It again just comes down to personal preference and what exactly you want to build/do with your ships.

When it comes to firepower...it again comes down to personal preference, tech levels and some hulls/towers that restrict gun sizes. With the upcoming patch introducing "defects" with ship construction/components, it might not necessarily be the best option to go with the "latest and greatest" tech you unlocked since the "defects" aspect is supposed to represent the dangers of using untested or brand new tech (so maybe you want to hold onto those older 14 inchers for just a while until your new 16 inchers are working smoothly).

When it comes to my BBs, I would say that the 14-16" guns are probably your most cost-effective options. Anything smaller than 14 usually doesn't pose much of a threat against BBs (but can annihilate cruisers), and anything bigger than 16 usually has too long of a reload to be very useful, not to mention being very heavy and requiring some of the biggest hulls in the game. I also try to follow a "gun vs time era" design process where after a certain year...I stop using a certain size gun on BBs because they are either obsolete or outmatched (it loosely follows historical examples).
1890-1900: 10-12" guns
1900-1920: 12-14" guns
Mid-Late 20s: 16" if available, nothing smaller than 14"
1930-1940: Nothing smaller than 16's if I can help it

Again, tech levels will limit your choices and their effectiveness here. And while this is (mostly) arbitrary and just my personal methodology, 10 inch guns are quickly outclassed once you get to actual dreadnought hulls--and by that time, you usually have larger gun options anyways. 12 inchers might be the "most accurate" guns available, but into the mid to late 1910s (so essentially the years WWI was going on), 14 inch guns are usually the new standard. Once you unlock 16 inch guns, you should probably never go back to guns smaller than those...because the AI likely won't go smaller, and will usually have at least one ship class that goes larger than that if you haven't completely bankrupted them. Now, all of what I just said could be rendered null and void by research and tech levels. If your main enemy only has Harvey armor in the late 1910s and you can somehow get good enough penetration values...maybe your 12 inch guns will still be good enough. Your enemy decided to go thin on the armor so your 16 inchers only over-penetrate? Maybe your ships with 14 inch guns are your better option for dealing with them, or maybe just swapping your 16" shells to a lower-penetration option would work (idk why you have to go through and entire refit/retrofit process just to swap shell types but whatever).

With your other ships, it is more or less the same as above...but the choices come down to more of a "what do I want these ships to do" basis rather than a "what is the best gun available" basis. BCs have access to BB size guns on bigger CA hulls and usually hunt cruisers, most CAs will have guns around 8", most CLs will have guns around 6" and most DDs will have guns around 4" or 5".

So, in closing...a lot of this is very arbitrary, varies from person to person, and largely comes down to your own personal preference and how you want to use the ships you build. I've built DDs with 6x2 5.5" guns that wound up being a DD and CL's worst nightmare, and I've built CAs that are high-speed rapid-fire gunboats (the largest gun was 7", then it was packed to the gills with 2-4" secondary guns and it was used to terrorize convoys and DDs).

You can (mostly) build what you want, how you want it...but what would make a "balanced" or "good ship" when it comes to armor and firepower is largely dependent on what exactly your enemy is throwing at you, and what tech you have available to work with.

Thanks thats helped tons

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  • 2 weeks later...

Small add to the good summary of HistoricalAccuracyMan, to show another personnal approach:

I remain faithful to 12'' longer, but with a "doped" version: increased to 12.8'' (325mm), longest barrels, super heavy shells, Caped HE and max Caped AP. I only go bigger in the late 20s, when mark3 of 15'' or 16'' become available. 
At this time, my BC are divided into 2 groups:
- Big hulls with same guns as BB, which are like fast small BB.
- Small hulls with 12.8'' guns, which are like heavy boosted CA. 

For small ships, I don't really have advices because I didn't often use them before update 1.09 and now I still investigate for good designs. 

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