Eeek, am I doomed?

[capnq]

Possum said:
ECM III 60%
Stealth Armor III 15%
Scattering Armor III 15%

Do all three of those stack, for a total defensive to-hit bonus of 90%?

Yes, they do. But that doesn't necessarily mean you're doomed. There are a couple countermeasures you can use, depending on the situation.

1) The attack bonuses from combat sensors, ship and fleet experience stack the same way.

2) Missile weapons are unaffected by defense bonuses, if you can flood whatever point defenses the opponent has.

3) Fighters, Wave-Motion Guns, and another weapon that I'm blanking on also have attack bonuses.