EVE New Citizens Q&A

Look at the ship's traits and see if it has bonuses to a particular type of tanking,
generally (though not always) you don't waste a bonus.

If it's not then look at the attributes tab and check the shield and armour hp and resistance, this should give you a clue.

Generally though the races are known for particular types of tanking I.e. amarr = buffer armour, gallente = active armour, caldari = shield .

There's loads of exceptions to this though so you should check the ship's individually

emphasising this.

Pic armour or shield, not both

Because hardcore guys do not know how to bait properly ;) There is very limited number of tasks, when some certain ship can and should use both low and medium slots for tank.

But in the other 99 % of job you want to do you need low slots for tank and middle slots for damage or opposite. Usually low slots are for armor/hull tanking, middle slots are for shield tanking. There is a whole theory what is better unde what circumstances and why, but almost always there are exceptions form that rules.

TL;DR version : so you do not waste too many slots on tank.

When an enemy sees you, they will shoot you with everything they have. Defending against that is like defending against a tsunami wave: you put all the effort into making the tallest wall possible, rather than 2 smaller walls.

Your ship will have a limited number of slots, and limited power and CPU for modules, so if you're going to tank it, put all that power and the maximum number of slots that you can use into making one big defense (shields, or armor), rather than two small defenses.

Because you only have so many slots. If you are going to tank, you want it to be the best tank it can be. But depending on your ship, skills, and purpose, you need to have some or all of damage, fitting, capacitor, ecm, and propulsion modules somewhere. The better tank is to have one set of slots dedicated to it, and the other set of slots doing all the other things (with certain exceptions, your main prop mod is always going to use a midslot for example). If you split the tanking duty, you also end up splitting the duties of everything else, so you might not have many more "tank" modules fitted, but they are now spread in to two weak tanks rather than one solid one (resist modules are the ones that suffer most in this situation, as they are only applying to half the tank, rather than all of it).

Also, if you run an active tank, you only have so much capacitor. If you are running twice as many repair modules, your capacitor is going to crap out twice as fast (and since the slots you could have put cap recharge or booster modules in are fitted with the other tank, it'll likely crap out even faster).

This is, by far, one the most coherent explanations I have seen regarding the rule "never duel tank." I am saving this for future use.

A common topic. Here are some of my common replies (read them all):
https://forums.eveonline.com/default.aspx?g=posts&m=3844723#post3844723
https://forums.eveonline.com/default.aspx?g=posts&m=2956645#post2956645
https://forums.eveonline.com/default.aspx?g=posts&m=4114882#post4114882
https://forums.eveonline.com/default.aspx?g=posts&m=4233022#post4233022

The amount of ships that use dual tank are by far a big exception to the rule.

Specially cause most of those ships have a very specific duty, which by performing that duty, you by then should already be well into the knowledge how tanking works.

Some ships like the breacher are almost always dual tanked due to nothing else useful fitting in the low slot that uses less than 14 cpu (full T2 AB/Rockets/Meta4 scramweb and a booster)

In most cases however, you will have enough resources to fit something beneficial to your tanking style in your spare mids or lows, or even something to help your offensive (Overtanking will cripple your dps)

This.

Another thing I'd add.

Modules that add absolute HP ("800mm Reinforced Steel Plates II" or "Large Shield Extender II") should not be used alongside modules that consume capacitor to 'heal' damage to you.

There are exceptions but these are rare.