Was having that question for a long time, but always forgot to ask.
Do ship modules stack? When i say stack i mean this:

1. If you use 2 weapon modules with 13% crit chance each, does it mean that those 2 weapons has 26% crit chance and they fire in the same time?? Or they fire separately and chance is calculated same way?
2. Do defensive modules that give crit. damage reduction stack to 100%? or they count separately? This one is very important, as if they stack and you can make 100% that is just op kinda :P

Weapon modules don't stack, each of them do their own damage with their own effects. Defense modules and support modules stack their effects however. Absorbtion from shields and armors has a diminishing return effect though, they can never reach 100%. 

Foraven wrote:

Weapon modules don't stack, each of them do their own damage with their own effects. Defense modules and support modules stack their effects however. Absorbtion from shields and armors has a diminishing return effect though, they can never reach 100%. 

No no, you seems like did not undertand what i asked.
There is a specific defense module, that has unique passive 50% critical damage reduction.
Does that effect stack?

Neron wrote:

Foraven wrote:

Weapon modules don't stack, each of them do their own damage with their own effects. Defense modules and support modules stack their effects however. Absorbtion from shields and armors has a diminishing return effect though, they can never reach 100%. 

No no, you seems like did not undertand what i asked.
There is a specific defense module, that has unique passive 50% critical damage reduction.
Does that effect stack?

It does.

Also just an FYI, Critical Damage does not work in ES2 as it does in many other games. Successful Crtitical hits do not provide any additional damage above and beyond their base damage. What a Critical hit provides in this game is a 100% penetration of both the enemy Shields and Hull plating, which normally reduce the damage recieved by some % before it is applied to the Ships HP. When a shot achieves a critical hit in ES2, it will deal 100% of its normal damage, with no portion of the damage being reduced by the defense modifiers of the enemy ships Shields or Hull Plating. 

The modules that decrease the damage from critical hits actually just reduces the enemies chance to bypassing their defenses. Having two of the 50% critical damage reduction mods will not prevent the damage from critical hits to the ship outright, you will still recieve some damage.  It will just prevent them from bypassing your defense modules damage reduction, and thus they will deal regular damage as if they did not crit at all. 

gap81 wrote:

The modules that decrease the damage from critical hits actually just reduces the enemies chance to bypassing their defenses. Having two of the 50% critical damage reduction mods will not prevent the damage from critical hits to the ship outright, you will still recieve some damage.  It will just prevent them from bypassing your defense modules damage reduction, and thus they will deal regular damage as if they did not crit at all. 

As you mentioned crit. ignores all defenses and because of that i always thought that if you have 2 of those modules, you could completely ignore all the TRUE damage that sometimes weapon dealt.
Briefly what 2 of those mod did (how i thought)
Reduced all the crit. (true damage) to zero which lead to decrease of crit. stat value to 0.
Also worth mentioning that there are some weapons that have passive to ignore defenses completely, which means that game sees it as a critical damage and you can use those 2 mods to completely nullify its damage?