Fire starting question

[Ensign_Cthulhu]

As near as I have deduced, it works like this, and I would like someone to check my reasoning against cold reality.

All AP fire chance is naturally zero.

HE fire chance is zero if the shell shatters or bounces.

HE fire chance for multiple shells is a series of independent events (the chance of any shell causing a fire does not depend on whether the last shell caused a fire or not).

Therefore, if an HE shell hits and neither shatters or bounces:

Probability of fire = 1 - (probability of no fire).

For a single hit with a fire chance of 10% (to keep the maths simple), probability of no fire = 0.9.

For two hits in a row, probability of no fire = 0.9 x 0.9 or 81%

For three hits in a row, probability of no fire = 0.9 x 0.9 x 0.9 = 0.729 or about 73% And so on until so many hits have been made and the probability of avoiding fire is so low that it becomes equivalent to zero.

Or is there some wrinkle in the mechanics I have not correctly deduced?

[centarina]

fire chance is   same whether it pens or not.     there is a modifier though for each ship for fire. 

[Ensign_Cthulhu]

A modifier for the ship being hit, or the ship doing the hitting? I know each ship has its own peculiar firestarting chance based on its guns (though I set four with my Leander's secondaries alone last night), and that the mounting of various flags alters things, but I didn't know that each particular ship had its own particular chance of getting ignited.

As for the shattering vs. not shattering... interesting.

[centarina]

high tier ship typically has lower chance to get set on fire when it gets hit.       this isn't published unlike the chance on guns.        HE fire chance is same no matter what it does though.      I figure I actually set about 1/2 my firechance overall.  

[_ENO_]

http://wiki.wargaming.net/en/Ship:Fire 

 

You can view the entire list- per tier and type not necessarily per ship- at the link above. 

[Madwolf05]

Fire chance:

* Shattered or not, fire chance doesn't change.

* Every ship gets a base fire resistance that goes up for every Tier, except Carriers.

* All ships have a base of 4 fire points.

* Cruisers and Destroyers put out fires faster naturally than BBs or CVs.

* Hitting a ship in a spot already on fire gives a 0% fire chance.

* Hitting a ship on the side at the waterline, or on it's tallest mast still sets the ship on fire in that section. So if you struggle to set bows or afts on fire, just focus on hitting them anywhere instead of the deck or lower superstructure.

[Lert]

HE fire chance isn't dependent on penetration. HE 'shatters' have the same chance for fire as penetrations that do damage.

[IfYouSeeKhaos]

7 minutes ago, Lert said:

HE fire chance isn't dependent on penetration. HE 'shatters' have the same chance for fire as penetrations that do damage.

That's true...I've had battles where I'm unloading on BBs in a DD w/HE & in the end I've had 50-60 hits & done 20k fire damage in 5 fires & 0 shell damage...standard outcome when firing at a BB(especially KM)2 tiers higher than you in a DD.

[WanderingGhost]

1 hour ago, ENO75 said:

http://wiki.wargaming.net/en/Ship:Fire 

 

You can view the entire list- per tier and type not necessarily per ship- at the link above. 

This and shatter/no pens still start fires, why a Mahan just started 4 on my Warspite while taking 0 damage hits from it after starting 2 before that.

[Destroyer_Zeka]

HE can start fires whether it pens or not. And landing more hits doesnt increase the chance; its static chance per shell hit. Ive had games where every other salvo started a fire and then I've also had games where I land 400 shell hits and get 2 fires total

[Ensign_Cthulhu]

On 12/16/2017 at 8:45 PM, Destroyer_Zekamashi said:

HE can start fires whether it pens or not. And landing more hits doesnt increase the chance; its static chance per shell hit. Ive had games where every other salvo started a fire and then I've also had games where I land 400 shell hits and get 2 fires total

I appreciate the fact that landing four out of four doesn't magically increase the probability; i.e. that there is no salvo probability buff. However, as you land more hits, your cumulative chance of starting a fire rises by the laws of probability. In effect you are throwing for heads or tails - fire vs. not-fire - with a heavily weighted coin, and eventually you must get "heads" (fire). The odds aren't difficult to calculate and they do rise with every hit you make, even when the events are independent (which they are, given what you yourself have said).