I want to know if I grasp the basic concept of applied DPS and EHP and how it works using this example. Please let me know if I’m right or wrong.

A defending ship has 70% resist across the board.

The attacking ship can apply 600 raw dps. So the attacking ship’s real DPS against the defending ship is 180 correct? (600 * (1 - 0.7%))

And just to add a new layer to this. If the defending ship is getting reps from a logi of say 180 ehp per second, then the defending ship cannot be killed since the reps it gets is equal to the applied dps?

You are right that the ship will not die if it is receiving 180 ehp damage and also 180 ehp remote repairs every second.

However, it probably isn’t receiving both every second, but is receiving those values on average every second.

In reality, remote repairs take a few seconds to cycle. Weapons also can take various times to cycle. Some weapons fire often and fast for little damage, while other weapons (artillery weapons most notably) deal massive damage each shot but can take many seconds to reload before they can fire another shot.
Even if both weapons could have the same dps, the slow heavy hitting weapon has a much higher ‘alpha damage’, which is the amount of damage per shot, rather than damage per second. High alpha damage causes your hitpoint losses to be happening in much bigger chunks.

Depending on the amount of hitpoints you have, it is possible that the ‘high alpha’ damage shots bleed through your shield to armor or through your armor to hit your hull hitpoints if you don’t have enough shield or armor hitpoints.

And in that scenario, even if you get remote shield or armor repairs for 180 EHP/s and the incoming damage is ‘only 180 EHP/s’, you may still die after enough of those shots have bled through to your lower layers of survivability that aren’t getting repairs.

It’s a strategy that some fleets use. Bring enough alpha damage to volley enemy ships down before they can even catch repairs.

And single ships can do it too. Tornados in high sec like to one-hit ships for about 10k damage. Even if you have a nice repair module to repair all their dps on your ship, if you don’t have enough hitpoints to survive such a volley, you’re going to explode when hit.

This is insufficient an assumption to be able to claim your DPS numbers are correct. You’re trying to craft a scenario where a turret or launcher has a 1.0 hit chance, because applied DPS is a factor that is equal to or less than hit chance, and you want that to ultimately be 1.0. So you’re forcing a 1.0 hit chance scenario.

You’re missing this assumption for a turret:

“the target is in optimal range”

You’re missing this assumption for a launcher:

“the target’s signature radius is larger than the explosion velocity of the missile”

I know you intended one or both of these, just wanted to share the knowledge.

I came to say what Gerard said, but with a more extreme example.

The answer is no, it may still die.

Suppose the reps cycle time is 100 seconds. But you get 18000 EHP! That’s 180 EHP/s as stated in your problem. Suppose the weapon cycles every 1s effectively dealing 180HP/s damage after resists and transversal/explosion velocity and signature radius are taken into account.

That means you take a total of 18000 HP damage!

That means you need 18001 HP in your reppable HP bar or you’ll die before reps “land”.

A resist value is the percent of the applied damage of each type you negate.

You have 20% Thermal resist and 0% EM resist, and someone shoots you with a 50/50 EM/Thermal laser. It deals 100dps you you, after tracking and range is factored in.

The 50 thermal dps is cut down to 40 due to the resists, where as the 50 EM damage is not mitigated at all. Therefore, you are taking 100EHP/s of damage, but are only really getting damaged by 90HP/s. EHP is calculated using the average resist value across all damage types, then adding one and multiplying by the HP value. This is done for Shield Armor and Hull separately, and the values are added at the end.

“180 EHP of Reps” really doesn’t make sense, it’s just in HP/s. If you assume a ship with 0/20/40/50% resists in shield for EM/Th/K/Ex the reps will be more effective in terms of EHP for different attackers. If the ship was taking EM damage, the logi (at 100 HP/s rep power) would only be able to rep its baseline 100 EHP/s value. If taking Explosive, however, the logi jumps up to 200 EHP/s, which is why having high resists is important for any fleet with logi.

In short, a logi ship can indeed rep 600 dps applied to a 70% resist ship with only 180 HP/s rep power, as long as the damage never “punches all the way through” a layer, leading to wasted reps when all the way full every cycle of damage.