Ishtar vs guristas part 2: Shield tanking

In response to my earlier post about plexing ishtars I've received several comments about shield tanking fits and decided it was high time to do an amateurish comparison. On the surface shield-tanked ishtars have much better tanking numbers, but we also need to take into account the peculiarities of missile damage.

When missile damage is calculated, two important things beyond damage and resists are taken into account: Explosion velocity and explosion radius. The calculation is too complicated for me but fortunately EFT exists so we don't have to do the math. Generally, when missile explosion velocity is less than ship velocity, damage is reduced; and when missile explosion radius is larger than ship signature radius, damage is reduced. Or something like that.

The basic issue with passive shield tanks when used against missiles is that shield extenders and shield rigs increase the signature radius of the ship, which increases incoming damage. Additionally, an afterburner uses a mid slot which otherwise would be used to greatly increase shield recharge so one must pick between speed and a higher DPS tank. An armor tank, by comparison, tanks less raw DPS but the signature radius never goes above the base value and an afterburner does not affect the tanked DPS number.

To compare armor and shield tanks I used a ratting raven and ratting drake with the BCS removed to make damage graphs against a shield and an armor tanked ishtar. Armor and shield tanked ishtar have pretty similar resist numbers, so I called them even and set the resist option on the DPS graph to "not used" because that gives numbers which are easier to compare. It does not give realistic DPS values for incoming damage from rats, but should return a reasonable ratio of how much damage would come in from missiles when armor vs shield tanking.

The damage dealers

Ignoring the neut issue, let's compare tanks. Using 16% therm and 86% kinetic damage incoming, a shield tanked ishtar resists 1839 raw DPS while an armor tank does 1244. As the shield tank resists 47% more raw DPS, if it receives less than 47% more incoming damage from missiles it is better at tanking.

Shield and armor ishtar setups

Damage graphs:

Red: drake vs shield ishtar (105 DPS)
Green: drake vs armor ishtar (28 DPS)
Dark blue: raven vs shield ishtar (39 DPS)
Light blue: Raven vs armor ishtar (9 DPS)

Oops! The shield tank is receiving 3.75 times as much damage from heavy assault missiles and 4.3 times as much from torpedoes.

One way we could reduce damage input significantly is by adding an afterburner and using two shield hardeners:

Shield ishtar (version 2)

Damage graphs

This reduces incoming damage to 37 and 13 respectively, only 32% and 44% more than the armor ishtar receives; but keeping this build cap stable means raw tanked DPS is reduced to 1160 - lower than the armor tank - and depending on the afterburner means it, too is vulnerable to neuts.

In conclusion: Although a shield ishtar would work just fine in lower damage situations, the armor build is better at tanking.