The stacking penalty applies to the bonus, not to the module.
If you have a thermal hardener and an EM hardener fitted, both would provide the full resist bonus. If you add omni-resist plating, its thermal and EM bonuses would be reduced because of the stacking penalty, but its explosive and kinetic bonuses would not.
The precise formula is somewhat complicated, but it can be summarized as:
- The first module provides 100% of its bonus.
- The second provides ~87% of its bonus.
- The third provides ~57% of its bonus.
- The fourth provides ~28% of its bonus.
- The fifth ensures your fit gets posted in a "fail fits" thread on the forums.
The order you fit the modules doesn't matter; the one with the largest bonus will always be considered "first".
Some modules (notably Damage Control Units) are exempt from stacking penalties.
There are a few tricks to easily survive gate-camps:
1st point:
Never use straight lines in 0.0. Why? Because a lot of 24/7 sitted systems only have 2 gates. The bubble will just be on the line right beetween the gates and you'll automatically be thrown right into the bubble.
If possible, you'll want to warp to a planet, which is far away from the direct path, then warp to the destination gate. That way, you'll probably manage to go around the bubble.
2nd point:
Use a shuttle. Or any ship you'll be able to fit for fast spinning and good accelerations. Remember those omg-wtf-unlimitedspeed-nano-frigates?
(Or a full tanking drake should do the trick if you just go for a small-camp, they'll never be able to shut down your shield).
3rd point:
Try to know all the systems on your itinerary, and try to look for unusual paths.
You can look here for dangerous systems (stats for the last 3 hours), and you'd better check all the systems you'll go through, just to be safe.
Remember: the shortcut is a lie. The shortest path between populated regions will probably be heavily camped.
Here are a few usefull links:
- Ombeve (A good .pdf map. Print it, and stick it all over the room. Seriously.)
- Dotlan (Want some info for the next system? choose the region, click the system on the map, and look at the ship-kills stats. Instant camp-gate indicator)
- ICSC Jump planner for those who fly carriers. (It'll help you to reduce costs, you'll just have to check dangerosity for the suggested systems)
About the cloacking subject, the training time for a blank new character (without optimisation:
1) To use a Prototype Cloaking Device I -> 21h 30min;
2) To use an Improved Cloaking Device II -> 1d 23h 20m;
3) To use a Covert Ops Cloaking Device II -> 7d, 3h, 30min, + 23d 15h 50 min for the T2 frigate.
Best Answer
The exact same stacking penalty applies to their use as most every other module in the game:
roughly.
So, with a Tech1 target painter bonus of 30% and a target signature radius of 100m, the first would give a sigrad of 130m, the second would be 163.8m, the third 191.85, etc. It is multiplicative (though not in the sense you're asking), but also subject to stacking penalty.
To use an in-game example ( just tested on Singularity to confirm ): The Moa has a sigrad of 135m. A T1 painter has a 25% bonus to sig radius. This is what I observed:
No modules: 135m
One module: 168 // +25% // net +24.44% (EVE truncates)
Two modules: 205m // +21.725% = ( 25% * 86.9%) // net +51.85%
Three modules: 234m // +14.275 = ( 25% * 57.1% ) // net +73.33%