How do partial penetrations work?

[SPANISH_AVENGER]

I did a test to see if really thick armor really works: a derp battleship with nothing but armor! Armored with a 1,500mm thick belt AND extended belt, against 10 Battleships, at 2,000 meters.

I am quite confused because the battle log indicates: "belt/extended belt partial pen, X damage", and I wonder how guns with 1,000mm pen at point blank can "partially penetrate" and cause damage through a 1,500mm thick belt.

But there are other times where it simply says "blocked" and deal no damage, which is what I would have expected to happen at all times.

So, how do partial pens work?

 

Edited January 28, 2021 by SPANISH_AVENGER

[Jatzi]

If I had to hazard a guess I'd say it could maybe be shells that penetrate some of the armor but then explode maybe pushing a hole through the rest of the armor and causing some minor damage? Realistically in the game armor penetration is an RNG thing and depending on the relative armor and armor pen and maybe angles(?) there's a chance for pens, partial pens, and blocked or deflected shots. And if the partial pen wins out then the dmg of the shell is reduced by some amount and that's the dmg that gets applied. 

Real life though I found this at http://www.navweaps.com/index_nathan/Penetration_index.php-"Partial Penetration - The forward half of the shell penetrates the armor while the rear half is rejected; or, for hits over 45° obliquity, the nose and upper body are rejected while the broken lower body penetrates - only if the shell breaks, of course, but most will at such a high obliquity below the Naval Limit."

That site also mentions these definitions -

Holing Limit - The shell makes a caliber-width hole entirely through the plate without enough of its body weight completely penetrating to meet the Naval Limit definition. Hits that fail to meet this criterion can still cause limited damage, usually more localized to the area behind the struck plate, perhaps causing shock effects only.

NL

Naval Limit - If undamaged, 100% of the shell's body weight achieves complete penetration (ignore the AP cap and windscreen); or in the case of a broken shell, 80% of the body weight penetrates. Beyond this, the shell's post-impact condition remains undefined; it may be capable of exploding, or it may not.

I'm unsure if the above partial penetration would cause too much damage but the hits that fail to meet the holing limit sound like the games partial pens.

 

That site seems pretty solid for at least some guns. @Nick Thomadis I'm sure you've got your own resources, especially at this point but another one(potentially) can't hurt right? It's penetration charts btw

Edited January 29, 2021 by Jatzi

[The Land]

"Partial penetration" could also be used to mean the circumstance where the shell lodges in the armour but doesn't make it all the way through it. This can still result in 'spalling', or fragments of the inner armour face coming loose and spraying into the ship. That can still be pretty lethal.

[Right]

On 1/29/2021 at 12:16 PM, The Land said:

"Partial penetration" could also be used to mean the circumstance where the shell lodges in the armour but doesn't make it all the way through it. This can still result in 'spalling', or fragments of the inner armour face coming loose and spraying into the ship. That can still be pretty lethal.

As there are more then one way to die, global stractural damage sometimes important, partial penetration means that the shell for some reason didn't came all the way throu the armor but did enough stractural damage to be of importance. It might chunk a bit of the armor off or broke something in the structure that made enough impact to change the outcome of the battle.