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Soshi_Sone

Another Way to Look at Fire Prevention

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I thought I would provide some information that might help folks understand the magnitude of the Fire Prevention percentage reduction.  This is just a discussion about the percentage fire reduction, and NOT a discussion about the reduction of fire zones from four three.  And therefore, not really an amenable thread for the discussion of FP overall.  Besides, there are other threads for that discussion.   The below is intended to give players a feeling for what they are getting.

First off, the 10% reduction is NOT a reduction in the overall chance of catching fire.  It is the reduction in each shell's base fire chance.  This base fire chance is further reduced (or increased) by other percentage adjustments.  For now, we'll just look at the 10%.  The best way to get a feel for what the 10% buys you is to take a shell's base fire chance....move the decimal place over one place (i.e., a 10% shift) and then reduce the base chance by the resulting number.  Let's take an example:

Let's say a base shell chance of fire is 46%.  To find a 10% reduction, we will move the decimal place over one, giving us 4.6%.  Now subtract this from 46% and you get 41.4%.  That is, FP reduces the BASE fire chance of each shell from 46% to 41.4%.  Ergo, a 10% reduction.

Another example, using a lower percentage base chance of 20%.  Move the decimal one place gives us 2%.  Subtract and we get 18%.  Hence, FP reduces the BASE chance of fire from 20% down to 18%.

Now let's talk tiers.  Each tier has its own "built" in fire reduction.  T1 starts with a "1" (no reduction)  By the time you get to T10, the reduction is .5 for top hull.  In the case of a T10, a shell's BASE fire percentage is reduced by 50% (a great thing!!!).  It also reduces the net effect of the FP percentage by a similar amount.  That is, a 10% reduction (normalized by 50%), is a net 5% reduction.  What does this really mean in terms of tiering.  I did some calculations to determine how much the FP 10% buys you related to each tier..here's what you get.  Left column is the tier with FP.  Right column is the tier that has an equivalent fire reduction WITHOUT FP.

T1/T2 ~ T4

T3 ~ T4/T5

T4 ~ T5/T6

T5 ~ T6

T6 ~ T7

T7 ~ T8

T8 ~ T9

T9 ~ T10

 

What does this tell us in practical terms.  From T6 onward, running FP gives you the equivalent fire reduction of a ship one tier above you that is not using FP.

Extrapolating the above to one's own play style and skill choices is up to each player. 

 

 

Edited by Soshi_Sone
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Nice write-up, and an interesting perspective on this subject that I never really gave much thought to before.  +1

Sadly though, Conqueror still laughs at anything that remotely even suggest fire prevention.

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The main point of the skill is to stop double superstructure fires. The reduction is just a bonus.

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Fire chance and fire prevention chance simply increases or decrease avg damage done/received over the long run.

 

It's equivalent to a flat boost in HP, but just with more steps. 

 

There's zero reason for a ship that's expecting to take shots often to not choose all survivability skills.

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So a Zao has a 19% fire chance and is firing at a tier ten BB with FP (-10%) and Damage control 1 with -5% fire chance. What is the Zao's actual chance to start a fire?

In your example you are using the ships reduction values based off of the ship that is firing at you fire's chance. Would you simply combined both the -10 and -5% fire chance  prevention to have a -15% number off of the Zao's stated 19%?

After we get to that new fire chance for the Zao of 16.15% we take a blanket cut of 50% because the ship in question is tier 10 and the Zao's realistic fire chance per shell is 8.075% 

 

Assuming my math is correct or close to it, DE on a tier ten ship with a value +2% fire chance, really is actually under 1% against every tier 10 ship that is at least using dam con 1. Is that worth 3 captains points?

Edited by Sweetsie

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1 hour ago, Sweetsie said:

So a Zao has a 19% fire chance and is firing at a tier ten BB with FP (-10%) and Damage control 1 with -5% fire chance. What is the Zao's actual chance to start a fire?

In your example you are using the ships reduction values based off of the ship that is firing at you fire's chance. Would you simply combined both the -10 and -5% fire chance  prevention to have a -15% number off of the Zao's stated 19%?

After we get to that new fire chance for the Zao of 16.15% we take a blanket cut of 50% because the ship in question is tier 10 and the Zao's realistic fire chance per shell is 8.075% 

 

Assuming my math is correct or close to it, DE on a tier ten ship with a value +2% fire chance, really is actually under 1% against every tier 10 ship that is at least using dam con 1. Is that worth 3 captains points?

 

Your numbers look correct to me.    

 

Edit:  One other thing.  I've only looked at the base fire chance change as adjusted for tier.  In the case of our 46% base example, we showed a 10% drop gave us a 4.6% reduction, which when also adjusted for tier results in a fire chance of 23% versus 20.7% respectively.  This 2.3% seems like a far cry from the 10% suggested by the skill.  There is another issue I'm working involving the probability of multiple hits and the chance for multiple fires.  If we take 8 hits using the 23% and 20.7% chance per shell, the result is 58.1% chance of getting 2 or more fires from the former vice 51.7% chance of getting 2 or more fires from the latter.  That's a 6.4% difference.  This calculation does not account for the hit box reduction using FP nor does it correct for multiple hits in the same box.   

Edited by Soshi_Sone

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1 hour ago, Sweetsie said:

So a Zao has a 19% fire chance and is firing at a tier ten BB with FP (-10%) and Damage control 1 with -5% fire chance. What is the Zao's actual chance to start a fire?

In your example you are using the ships reduction values based off of the ship that is firing at you fire's chance. Would you simply combined both the -10 and -5% fire chance  prevention to have a -15% number off of the Zao's stated 19%?

After we get to that new fire chance for the Zao of 16.15% we take a blanket cut of 50% because the ship in question is tier 10 and the Zao's realistic fire chance per shell is 8.075% 

 

Assuming my math is correct or close to it, DE on a tier ten ship with a value +2% fire chance, really is actually under 1% against every tier 10 ship that is at least using dam con 1. Is that worth 3 captains points?

I believe that fire chances are multiplicative, not additive. So the final fire chance for the Zao would be (19%)*(0.95)*(0.90)*(0.50)=8.12%

For DE, you just have to compare the before and after. If your base fire chance is 10%, then you get 12% with DE; this is an increase of 20%. You will always get 20% more fires regardless of how much fire prevention you’re facing, because 6% is still 20% more than 5%. DE is only useless on ships with high fire chance, because going from say 40% to 42% is only 5% more, whereas going from 5% to 7% is 40% more. Again, 40% more will always be 40% more regardless of the fire prevention modifiers.

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Using Sweetsie's example of a Zao shooting a T10 ship.  The source for all of this can be found on the Wiki here.

TLDR - Here we can see that a full Fire Prevention and DCM1 build reduces full flamethrower Zao's fire chance by 1.7%  That isn't an insignificant number but it is a far cry from the 10-15% people think it should be.

Fire Chance Formula
[Fire Resistance Coefficient] x ( 1 - [Damage Control Modification 1] - [Fire Prevention] ) x ( [Projectile Base Fire Chance] + [Demolition Expert] + [Signals] - [Inertial Fuse for HE Shells]) = Fire Chance

T10 top hull Fire Resistance Coefficient - 0.5005
Zao's Fire Chance - 19%
Zao's actual fire chance on a T10 ship - 9.5095%
0.5005 x (1) x (19) = 9.5095%

If we add in Fire Prevention and DCM1 it will look like this
Fire Prevention - 10% Reduction - This is not a flat reduction of the attacking ships fire chance.  It is more like a modifier to the baked in Fire Resistance Coefficient on the defending ship.
0.5005 x (1-0.10) x (19) = 8.5585%
DCM1 - 5% Reduction - Again this is not a flat reduction in fire chance, it modifies the Fire Resistance Coefficient 
0.5005 x (1-0.05) x (19) = 9.0340%
If we add in both we get the following.
0.5005 x (1-0.1-0.05) x (19) = 8.0830%

Next we can look at the things that buff fire chance.  These are all additive to the base fire chance of the attacking ship.
Base Fire Chance - Per Ship - This is listed in port, for this example it will be the Zao's 19%
Demolition Expert - +2%
Signals - +1% per signal for this example - The signals can add +0.5% for smaller caliber guns but for this example we are using the Zao
IFHE - -3% - For this example the Zao would take a 3% penalty. Smaller guns take only a 1% penalty.

Adding Demo Expert
0.5005 x (1) x (19+2) = 10.5105%
With full Fire Prevention
0.5005 x (1-0.1-0.05) x (19+2) = 8.9339%
You can see that adding in Demo Expert is only about a 1% increase when fighting someone with a full FP build.

Adding in Signals will net the same results as adding in Demo Expert alone.  There are two Signals and they each add 1%.  We can see what full Signals and Demo Expert can do though.
0.5005 x (1) x (19+2+1+1) = 11.5115%
If we add in full FP build.
0.5005 x (1-0.1-0.05) x (19+2+1+1) = 9.7847%

For those interested in what IFHE would look like.
0.5005 x (1) x (19+2+1+1-3) = 10.0100%
With Full FP Build
0.5005 x (1-0.1-0.05) x (19+2+1+1-3) = 8.5085%

Edited by Kyralee
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40 minutes ago, Peregrinas said:

I believe that fire chances are multiplicative, not additive. So the final fire chance for the Zao would be (19%)*(0.95)*(0.90)*(0.50)=8.12%

For DE, you just have to compare the before and after. If your base fire chance is 10%, then you get 12% with DE; this is an increase of 20%. You will always get 20% more fires regardless of how much fire prevention you’re facing, because 6% is still 20% more than 5%. DE is only useless on ships with high fire chance, because going from say 40% to 42% is only 5% more, whereas going from 5% to 7% is 40% more. Again, 40% more will always be 40% more regardless of the fire prevention modifiers.

I think the general pop simply thinks they are getting a massive fire chance increase and while it may be a 20% chance increase, that 20% is off of a much smaller number than most realize.

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35 minutes ago, Kyralee said:

Using Sweetsie's example of a Zao shooting a T10 ship.  The source for all of this can be found on the Wiki here.

TLDR - Here we can see that a full Fire Prevention and DCM1 build reduces full flamethrower Zao's fire chance by 1.7%  That isn't an insignificant number but it is a far cry from the 10-15% people think it should be.

Fire Chance Formula
[Fire Resistance Coefficient] x ( 1 - [Damage Control Modification 1] - [Fire Prevention] ) x ( [Projectile Base Fire Chance] + [Demolition Expert] + [Signals] - [Inertial Fuse for HE Shells]) = Fire Chance

T10 top hull Fire Resistance Coefficient - 0.5005
Zao's Fire Chance - 19%
Zao's actual fire chance on a T10 ship - 9.5095%
0.5005 x (1) x (19) = 9.5095%

If we add in Fire Prevention and DCM1 it will look like this
Fire Prevention - 10% Reduction - This is not a flat reduction of the attacking ships fire chance.  It is more like a modifier to the baked in Fire Resistance Coefficient on the defending ship.
0.5005 x (1-0.10) x (19) = 8.5585%
DCM1 - 5% Reduction - Again this is not a flat reduction in fire chance, it modifies the Fire Resistance Coefficient 
0.5005 x (1-0.05) x (19) = 9.0340%
If we add in both we get the following.
0.5005 x (1-0.1-0.05) x (19) = 8.0830%

Next we can look at the things that buff fire chance.  These are all additive to the base fire chance of the attacking ship.
Base Fire Chance - Per Ship - This is listed in port, for this example it will be the Zao's 19%
Demolition Expert - +2%
Signals - +1% per signal for this example - The signals can add +0.5% for smaller caliber guns but for this example we are using the Zao
IFHE - -3% - For this example the Zao would take a 3% penalty. Smaller guns take only a 1% penalty.

Adding Demo Expert
0.5005 x (1) x (19+2) = 10.5105%
With full Fire Prevention
0.5005 x (1-0.1-0.05) x (19+2) = 8.9339%
You can see that adding in Demo Expert is only about a 1% increase when fighting someone with a full FP build.

Adding in Signals will net the same results as adding in Demo Expert alone.  There are two Signals and they each add 1%.  We can see what full Signals and Demo Expert can do though.
0.5005 x (1) x (19+2+1+1) = 11.5115%
If we add in full FP build.
0.5005 x (1-0.1-0.05) x (19+2+1+1) = 9.7847%

For those interested in what IFHE would look like.
0.5005 x (1) x (19+2+1+1-3) = 10.0100%
With Full FP Build
0.5005 x (1-0.1-0.05) x (19+2+1+1-3) = 8.5085%

very nice work. still is an interesting question concerning is DE worth three points on high tier play when you look at the real numbers...add in factors on how much the chance is lower if a ship is already on fire or if you get two fires he immediately puts them out.

Many cases its counter productive to get two fires on the same ship.

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