Shields

This article explains the functional process of spaceship shielding. For tactical applications of shields, see Shield tanking, Passive Shield Tank, or Logistics.

What Is a Shield?

You can think of a shield as a sphere, completely enclosing the ship at a location just inside its Signature Radius.

Since the Signature Radius is the effective size of the ship – the area that is targeted by weapons – the shield intercepts any damage that occurs before it can reach the ship. At that point, the damage is filtered – some is rejected and the remainder is passed through to the ship's armor.

The ships shields have a different shield resistance value for each of: thermal, kinetic, EM, and explosive damage. Resistance indicates how much of that kind of damage will be rejected by the shield when the ship is hit by that kind of weapon. Resistance values are always shown in percentages – for example, "30% Thermal Resistance" means that the shield will reject 30% of the damage from any weapons hit that does thermal damage.

The shield also has a capacity which shows how many hitpoints of damage it would take to destroy, or "drop", the shield. In combat this shows as the outermost of three red rings on the pilot's dashboard display. A ship's shield also has a recharge rate which shows how fast the shield rebuilds itself while damaged. The base values for all of these can be found in the Attributes panel of the ship's Show Info window.

Example 1: Here are the shield values for a Caldari Kestrel Frigate:

• Shield Capacity in Hitpoints: 500
• Shield Recharge Time in Seconds: 625 (10.4 minutes)
• Shield Resistance: EM:0% Thermal:20% Kinetic:40% Explosive:50%

Example 2: A much bigger ship, the Minmatar Hurricane Battlecruiser:

• Shield Capacity in Hitpoints: 4250
• Shield Recharge Time in Seconds: 1400 (23.3 minutes)
• Shield Resistance: EM:0% Thermal:20% Kinetic:40% Explosive:50%

Notice that both ships have the same four shield resistance values. This is because the resistances are expressed in percentages. The Hurricane starts out with almost three times as many hitpoints, thus each percentage absorbs considerably more damage than will the Kestrel. In each case the shield recharge time tells how long it takes for shields to go from empty to 99% capacity. The actual shield recharge rate varies quite a bit in combat – this is discussed in the Shield Recharge Rate section, below.

Resistance and Vulnerability

Base resistances of hurricane battlecruiser. The four resistances shown for this ship show how much of each type of damage the shield will reject.

There are four types of damage, and a shield will deal with each separately based on shield resists.

Shield damage rejection and vulnerability.

Each of these resistance values also represents a corresponding "vulnerability" number that shows how much damage will get through the shield for each hit of that kind of weapon. The Vulnerabilities are always 100% minus the resistances. So, for example, a ship with these resistances:

Shield Resistance: EM:0% Thermal:20% Kinetic:40% Explosive:50%

would have these vulnerabilities:

Shield Vulnerability: EM:100% Thermal:80% Kinetic:60% Explosive:50%

This is the damage that would impact on the shield if the ship flew with no benefits from skills, modules or rigs.

Because of the way the shield damage reduction modules and rigs work, it is often more useful to focus on the shield's Vulnerabilities than its Resistances.

Shield Capacity

Shield capacity indicates how many hitpoints of damage it will take to drop the shields. (The ship itself is also protected by Armor and Hull defenses, and so it will take considerably more than than that to destroy the entire ship.) In general, the larger the ship, the larger the base shield capacity.

You can think of a shield's capacity as its current size; whenever the shield takes damage of any kind, its capacity goes down, and it shrinks. So while hits that do thermal, kinetic, EM, and/or explosive damage may be mitigated by the shield's resistance layers, any damage that does get through will be subtracted from the Shield Capacity value. This reduction will appear on the pilot's dashboard as a red mark in the outer shield ring.

IMPORTANT: When shield capacity drops below 25%, the shield will begin to "leak" damage through to the armor and/or the hull of the ship. A buzzer will sound when the 25% limit is reached. (Certain skills will reduce this leakage – see Shield Skills, below.)

Shield Booster and Extender modules add hitpoints to the capacity of the shield and increase the total amount of damage that the shield can take before it is destroyed. Because the total shield recharge time never changes, increasing the shield capacity will also reduce the shield recharge rate. Core Defense Field Extender rigs also extend shield capacity, but at the expense of Signature Radius.

Example: Small Shield Extender I

• Bonus: adds 400 hitpoints to the shield's total capacity
• Stacking Penalty: no
• Signature Radius Penalty: yes
• Capacitor Use: no
• Applies to damage type(s): all

Damage Type Resistance

As noted in the Resistance and Vulnerability section, above, weapon strikes result in one or more of four types of damage: thermal, kinetic, EM, and/or explosive. Various modules mitigate specific types of damage. These modules often have stacking penalties. and while dealing with those is a matter of ship fitting, and not are discussed in detail here, an illustrative example is included, below.

Shield Hardener and Resistance Amplifier modules reduce the Damage Type Vulnerabilities of the shield. Anti-Damage Type Screen Reinforcer rigs reduce specific Damage Type Vulnerabilites, but increase the ship's Signature Radius.

Kinetic Deflection Field I

• Bonus: reduces the vulnerability of the shield to kinetic damage by 50%
• Stacking Penalty: yes
• Signature Radius Penalty: no
• Capacitor Use: yes
• Applies to damage type(s): kinetic

Since you need a different module for each type of damage, and since most ships do not have enough medium level power slots to handle more than a few modules, it is difficult to use these kinds of modules to protect against all types of damage. One solution is to load the kind of module you need for the expected encounter. Another is to use a "multi-type" module that protects against all damage types.

Adaptive Invulnerability Field I

• Bonus: reduces the vulnerability of the shield to all types of damage by 25%
• Stacking Penalty: yes
• Signature Radius Penalty: no
• Capacitor Use: yes
• Applies to damage type(s): EM, explosive, kinetic. thermal

The following module is listed under Armor and Hull in the EVE Ship Equipment list. It has unique properties and is widely used in many different fits.

Damage Control I

• Bonus: reduces the vulnerability of the shield to all types of damage by 7.5%
• Stacking Penalty: none listed, minor exceptions may apply
• Signature Radius Penalty: no
• Capacitor Use: yes
• Applies to damage type(s): EM, explosive, kinetic. thermal
• Other bonuses: reduces damage to armor and hull
• Other contstraints: a ship may activate only one of these at any given time.

Using Shields

In some cases the technical construction of the ship dictates the use of Shields (or Armor) as its primary defense. Any ship receiving a bonus to shield capabilites would likely use shields. And because most shield modules use medium level power slots, a ship with more mid than low slots will tend to use shields.

For example, these ships will usually use shields:

• The ORE Procurer, a mining ship, receives a 5% bonus to shield hitpoints.
• The Caldari Moa, a cruiser, receives a 4% bonus to all shield resistances.
• The Caldari Kestrel, a frigate, has four mid slots and only two low slots.

On the other hand, these ships will usually use armor:

• The Amarr Prophecy, a battlecruiser, has seven low slots and four medium slots.
• The Gallente Incursus, a frigate, has a 7.5% bonus to Armor Repairer amount.

It is worth noting that many ships can use either shields or armor. In these cases the choice is a matter of fitting ... what is the goal of the fit, and what are the skills of the pilot?

IMPORTANT: Ships should use either shields or armor ... but never both. Some shield modules increase the Signature Radius of a ship and make it easier to target. Some armor modules decrease the speed of a ship and make it easier to catch. While there are benefit trade-offs that make this acceptable for one kind of defense or the other, there are few, if any, trade-offs that accomodate both.

Advantages of Shields

• Does not reduce speed or maneuverability
• As a first line of defense, leaves you with Armor and Hull as a fallback if shields go down
• Recharge on their own – no need to dock for repairs
• Shield recharge modules work more quickly than armor repair modules
• Low slots are available for weapon enhancing modules

Disadvantages of Shields

• Increases signature radius – ship becomes easier to target
• Fewer kinds of enhancement modules – less choice than with armor
• Shield recharge modules use more capacitor power than armor repair modules
• Mid slots are not available for EWAR, propulsion and scanning modules

Shield Tanking

The term "shield tanking" refers to the use of shields as a ship's primary defensive mechanism. There are three general approaches to Shield Tanking:

• Active – use modules that draw on the ship's capacitor to improve shield performance
• Passive – use modules that do not draw on the ship's capacitor; mostly to improve shield recharge rate
• Buffer – use modules that do not draw on the ship's capacitor; mostly to increase the shield's capacity and resistance

This topic is covered in depth in the course on Shield Tanking, and in the article on Passive Shield Tank.

Logistical Shielding

Logistical shielding is the use of one ship's modules to apply shield protection to a different ship. This is covered in the E-UNI courses Logistics 101: Introduction to Logistics and the document Guide to Logistics.

Ships that Use Shields

Every ship has a shield. Whether or not a pilot decides to expand and improve the shield is his or her choice. You can find lists of ships that are commonly tanked with shields, but unless you are in a drastic hurry, you are better off choosing a ship that fits your situation and THEN deciding whether to use shields or armor as your primary defense.

That said, here are the factors that you look for when you are thinking about shields:

• a ship bonus that favors shields over armor,
• a shortage of low or a surplus of mid power slots,
• more need to favor modules that improve weaponry (which tend to need low slots),
• less need for modules that support tackling and scanning (which tend to need mid slots),
• pilot skills that are biased towards shields.

Shield Skills

A variety of skills improve a pilot's use of shields. Some of these are important to all pilots, while others are most important to pilot's who "shield tank" their ships and depend on shields as the primary means of defense.

Basic Shield Skills

These will be useful to any pilot and should be trained as soon as possible at least to Level III.

Shield Management – 5% bonus to shield capacity per skill level

Shield Operation – 5% reduction in shield recharge time per skill level

Shield Upgrades – 5% reduction in shield upgrade powergrid needs

Tactical Shield Manipulation – Reduces the "bleed through" of damage when the shield falls below 25% by 5% per skill level

Shield Tanking Skills

These are of most use to pilots who depend on shields as their primary defense. Refer to the article on Shield Tanking for detailed information.

Shield Compensation – 2% less capacitor need for shield boosters per skill level

Thermal Shield Compensation, Kinetic Shield Compensation, Explosive Shield Compensation, EM Shield Compensation – 5% bonus to damage resistance per level for Shield Amplifiers of the type listed

Other Shield Skills

These require advanced training and are of little use to newer players.

Shield Emission Systems – providing shield capacity to other players ... used in Logistics.

Capital Shield Operation – 2% reduction in capacitor need for capital shield boosters per skill level

Capital Shield Emission Systems – 5% reduced capacitor need for capital shield emission system modules per skill level

Shield Recharge Rate

Measured shield HP during passive recharge from zero and theoretical shield HP from formula plotted. Click to enlarge.

Shield recharge rate as function of shield HP according to the formula. Click to enlarge.

It takes a certain amount of time to recharge a fully depleted shield. This figure is given as the Shield Recharge Time in the ship's Attribute window. Recharging, however, does not tick along like the numbers on a clock. The speed of actual HP recovery due to recharge, given in HP/sec, varies depending on how full the shields are (the current shield level). This may be referred to as "regeneration," to avoid confusion with the attribute on certain modules (see below).

As the shield takes damage, its level goes down. In response, the rate at which it rebuilds itself goes up. The increase in shield recharge rate continues until it peaks at 25% of shield capacity. At this threshold, the default ship Health Alert noise will sound, to warn the pilot that the shield is at its recharging limit. If it continues to take more damage than it can hold, the regeneration will drop off quickly. This means if constant damage is applied, the shield will regenerate less as it becomes empty, thus making it easier to shoot the armor below it.

THE MAIN POINT: In combat the shield will recharge at an increasing rate until 25% of its capacity remains; then the rate will fall off quickly towards zero.

Formula

Shield regeneration is exactly the same as the capacitor recharge rate calculation. Two numerical attributes are required: shield capacity, and shield recharge time. While the first is fairly obvious, the latter number is more muddied.

Unlike capacitor time, which is displayed in the ship's "show info" attributes panel (web example), the shield recharge time is hidden. Similarly, modules in game often refer to "recharge rate" - this modifies the recharge time number, not the raw regeneration in HP/s. This has some interesting consequences. Note directly that for this calculation – recharge time is not dependent on maximum shield capacity, as you might intuitively expect.

This has the effect that if two ships have the same "recharge time" attribute, and one has more capacity, then the one with the larger capacity will get more HP/s regeneration, and appear to 'repair faster'. In other words, recharge is calculated by percentage first; which is then translated into HP/s of regeneration.

...where:
C is your current shield HP.
C_max is your maximum shield HP.
dC/dt is your current shield regeneration in HP/s.
τ is shield recharge time divided by 5.

Average rate

The average shield regeneration per second can be computed by dividing the shield capacity by its recharge time.

Average HP/s = Shield maximum / Recharge time

The peak recharge Rate is 250% of average shield recharge. It occurs when the capacity of the shield is at 25% of its maximum value. Shield recharge rate drops rapidly below 25% shield capacity.

Fitting Multiple Modules with Stacking Penalties

Shield resistance modules are subject to Stacking penalties which progressively reduce the effectiveness of the modules if they alter the same attribute. In other words, the second module is less than 100% effective, the third even less so, and so on.

The penalty only applies to the module's impact on the affected attribute, and progresses as follows:

1st mod: 100.0% effectiveness

2nd mod: 86.9% effectiveness

3rd mod: 57.1% effectiveness

4th mod: 28.3% effectiveness

... etc.

The modules are penalized in order from least effective to more effective - the "best" module for that attribute will be the one that works at 100%; the "second best" one at 86.9%. It is not recommended to fit more than two or three resist modules that are stacking penalized.

In addition to stacking penalties the shield resists aren't added together directly. Two 30% unpenalized resist modules will not give your ship 60% resist profile. You can think that each resist module reduces incoming damage individually. With incoming hit of 100 damage the first 30% resist module would reduce the hit to 70 damage and the second resist module would further reduce 70 damage to 49 damage giving total resist of 51% instead of 60%.