"free" sensors?

[Deoxy (OP)]

So, I've noticed for a while (but never asked) that ships without sensors can still sense other ships by thermal signals (and colonies by EM signature as well, which are usually pretty large).

So... what good are adding passive sensors then?  Are the "free" ones just really weak?  What's the mechanic, here?

[welchbloke]

So, I've noticed for a while (but never asked) that ships without sensors can still sense other ships by thermal signals (and colonies by EM signature as well, which are usually pretty large).

So... what good are adding passive sensors then?  Are the "free" ones just really weak?  What's the mechanic, here?

IIRC every ship without any sensor has an inherent 0.5HS thermal sensor capability.

[Ziusudra]

A ship without any components has "Sensors 1/1/0/0". The numbers refer to Thermal/EM/Grav/Geo; for Thermal and EM the number is the sensor strength, for Grav and Geo it is survey points per hour.

With a thermal sensor strength of only 1, an enemy ship with a thermal signature of 100 would be detected at 100,000 km. With a sensor strength of 10 that same ship would be detected at 1,000,000 km.

[Thiosk]

I liken those ranges to looking out the window. 

Hey, whats that OH SHI--