They are all referring to the same thing: signature radius.
What is it?
A ship's signature radius (measured in meters) is a way to describe how "big" it is. If this were a primitively built shooting game with manual aiming, you could imagine it as a ship's "hit box". Note that it does not directly correspond to the ship's physical size. For example:
The Punisher is 65 m long, and the Rifter is 110 m long. However, the Punisher has a slightly larger signature radius, at 37 m vs the Rifter's 35 m. This means that the Punisher is "fatter" not only in its speed, but in how easy it is to hit.
What does all this even mean?
Signature radius has several applications:
- Higher signature radius = you are targeted faster. The bigger you are, the more quickly other ships can get a lock on you. This is why frigates are slow to be targeted, while targeting capital ships is a matter of a fraction of a second.
- Higher signature radius = you are easier to track. Signature tanking, or "speed" tanking, relies on being fast and with a low signature radius to not get hit (it is also a lie, but more on that later). This is also the same reason Drakes get hit by everything forever: their signature radius is huge.
- Higher signature radius = bigger missiles can hit you. The damage you take from missiles is directly related to the ratio between the missile's explosion radius versus your signature radius. While a rocket fired at a frigate feels like an explosive bullet, a torpedo fired at a frigate feels like this:
- Higher signature radius = you are more easily probed down. Probing down a frigate is much harder than probing down a battlecruiser
Okay, sig radius is important, but what can I do about it?
There are a few ways to increase, or "bloom", your sig radius. Remember, increasing it is bad for all the reasons listed above. They include:
- Shield extenders. These add a flat amount to your sig radius. Ships with a large armor buffer are easy to hit because they're slow. Ships with a large shield buffer are easy to hit because they're huge.
- Shield rigs. These increase your sig radius as the rig penalty. The increase can be reduced a bunch by training good rigging skills
- Activating your microwarpdrive (!). An active microwarpdrive increases your velocity by 400-500%... but also increases your sig radius by the same ratio. This is the reason that MWDs are generally completely ineffective at avoiding damage (unless you're using them to keep range, in which case they can be effective). This effect is extremely drastic: a MWDing Drake has almost the signature radius of a carrier.
- It needs to be noted that interceptors and assault frigates have this bloom factor drastically reduced. Zipping around with a MWD on is encouraged in those ships.
- Using Rage or Fury missiles. They just do. Note that the signature radius is increased for every launcher using these missiles. That means that a Drake with Fury's will have a larger signature radius increase than a Caracal with Fury's (7 launchers vs 5 launchers).
- Putting up a heavy interdictor bubble. Deal with it.
- Target Painter (on target). Perhaps the most underused electronic warfare, but it makes things like bombers awesome.
- X-instinct combat boosters. These can be expensive, though, are illegal in hisec, and can have severe draw-backs.
- Skirmish warfare links. Either from a battlecruiser, or bonused from a Claymore or Loki, the Evasive Maneuvering boosts can reduce the signature radius of everyone under the "command" of that ship in the fleet structure. This is the most common method, since it involves a massive boost to fleet effectiveness without putting the boosting ship in any serious risk. This method is very expensive, though, and requires great skills.
- Halo implants. This is the most expensive method of these three, and can lead to hilarious killmails.
- Armor tank, or get another ship. Some ships simply aren't meant to dodge fire. Try Minmatar ships, or speedy Amarr ships (yes, they exist).
Combining these methods can lead to hilarious consequences. For example, a Claw can have a signature radius twice as small as that of a Warrior II drone!
What are some standard/approximate figures for sig radius?
- 25 m - Light drone
- 30-45 m - Frigate
- 60 m - Destroyer
- 90-140 m - Cruiser
- 240-300 m - Battlecruiser
- 320-500 m - Battleship
Note that these figures are raw (before blooming factors). With bloom factors included, the ranges become rather big.
So... why does nobody care about sig radius?
Its effects aren't usually easily observable, and are often misattributed to tracking, explosion velocity, sensor boosters, etc.
This is also why target painters are underused and underestimated. At short range, webs are somewhat more useful at helping to hit things, while at long range, other EW is usually more desirable for more direct effect.
Still, awareness of sig radii and how you can use them to maximize your ship's performance in battle, combined with maybe a TP or two at the right time, can lead to... PWNAGE.