Penetration

This page is a work in progress.

Penetration behaves differently for every type of shell in World of Warships. While high explosive (HE) shells have easily understood mechanics, armour piercing (AP) shells have various conditions for dealing damage. Learning how each weapon type deals damage is crucial to intelligent ammo selection and ship balance.

High Explosive Shells
HE shells ignore impact angle and shell velocity when they impact a target. They explode upon impact and their capability of penetrating armour is dictated solely by comparing the static penetration value of the shell with the thickness of the armour. The shell does not travel into the hull of the enemy ship and usually cannot cause citadel damage. However, HE shells do have a bursting radius which deals damage to all modules and compartments it touches; some ships have citadel armour that is exposed to the outside (or within reach of the HE bursting radius) and thin enough for HE shells to penetrate.

Penetration Values
HE shells penetrate this value of armour plating regardless of angle. Most HE shells penetrate armour equal to or less than 1/6 of their caliber, rounded up. For example, 130mm guns have 130/6 = 21.667 penetration, rounded up to 22mm, which means all 130mm guns (barring the effect of IFHE) will penetrate armour of up to 22mm thick. -insert table of penetration values including general rule and exceptions-

Types of Penetration

 * Shatter
 * The HE shell did not penetrate the armour that it struck. However, shattered HE shells still do explode and may damage modules, while not dealing damage to the hull of the target ship.
 * Full Penetration
 * The HE shell penetrated the armour that it struck.
 * Citadel
 * Same as a full penetration, but some ships have citadels that have thinner plating and are close enough to the exterior layer of armour that the bursting radius of an HE shell can strike it.

Inertia Fuse for HE Shells
The commander skill commonly called IFHE increased the HE penetration values of all shells fired by a ship, in exchange for a significant reduction in fire chance. Determining the value of IFHE is a complex decision for many ships as it can provide a significant increase in effective damage output against some ships, but a significant decrease in damage output against others.

Armour Piercing Shells
AP shells go through a sequence of checks when determining whether or not they penetrate. While they are the most difficult shells to use properly they have the potential to deal the most damage of any shell types thanks to their ability to penetrate outer plating and strike at the vulnerable citadel of a target ship.

Types of Penetration

 * Ricochet
 * The shell did not pass the bounce check, and did not penetrate the outer layer of the target ship.
 * Shatter
 * The shell did not bounce, but did not have the penetration to pierce the target ship's exterior plating.
 * Full Penetration
 * The shell penetrated the exterior plating, activated its fuse, and exploded inside the target ship.
 * Citadel
 * The shell penetrated the exterior plating, activated its fuse, and exploded inside the citadel of the target ship.
 * Overpenetration
 * The shell penetrated the exterior plating and either did not activate its fuse, or it activated its fuse but exploded outside the enemy ship.

Semi Armour Piercing Shells
SAP shells share some characteristics of both AP and HE shells. Like HE shells, SAP shells fragment upon impact and have a fixed penetration value, but like AP shells they must first pass a bounce check to determine if they may ricochet.

Types of Penetration

 * Ricochet
 * SAP shells can bounce like AP shells if they impact the target at an angle that is too great. However, they generally possess much more lenient bounce angles.
 * Shatter
 * SAP shells possess much higher penetration than HE shells of the same caliber, but still can shatter when impacting thick armour.
 * Full Penetration
 * The SAP shell penetrated the armour that it initially struck.
 * Citadel
 * Same as a full penetration, but some ships possess thinner citadel plating that is close to their exterior layer of armour, which allows SAP shells of certain ships against certain targets to deal citadel damage.

Miscellaneous

 * Whether or not an HE shell penetrates does not affect its fire chance. Fire chance is calculated solely by the base fire chance of the shell, both positive and negative modifiers from signals and modules, and the target ship's tier. An HE shell that shatters is just as likely to set a fire as an HE shell that penetrates.


 * Damage dealt by various penetration types is only base damage. Shatters and ricochets deal 0 damage, overpenetrations deal 10% of shell alpha, and full penetrations usually deal 33% of shell alpha. These damaging hits are then modified by the effects of saturation(insert link to saturation and module page). Citadel hits always deal 100% of shell alpha and are not affected by saturation.