searchlights and nightfight

[Occam]

So how exactly do searchlights work? The space marines I know play with them, but are never quite sure how they work. I play xeno, so we don't have them.
How does it act when playing with nightfight rules? Do they need to roll distance to see?

[Lerra]

The unit using the searchlight needs to roll distance to see. If they succeed, then the searchlight goes into effect and the next units to shoot at the same target do not need to roll for nightfighting.

[Foreigner]

The unit using the searchlight needs to roll distance to see. If they succeed, then the searchlight goes into effect and the next units to shoot at the same target do not need to roll for nightfighting.

But when and how do I use them?

1) Can I use them if I'm shaken?

2) Can I use them if I smoked?

3) Can I use them if I moved flat out? (BA tanks / IG Valkyries)

[lobster-overlord]

it also "lights you up" meaning you become a valid target under normal sight rules to your enemies on their turn.

[doublek666]

used when shooting, before you roll to see if you can see the target. if you can shoot, you can use the searchlight,as needed

[Nabterayl]

In other words, the searchlight isn't a pseudo-gun that you fire. It adds an extra effect to the shooting of the vehicle that has it.

[Tynskel]

which also means it is bound by the vehicle firing rules, as well. ie, if the vehicle can't shoot, you cannot aim your spot light.

[DrLove42]

it also "lights you up" meaning you become a valid target under normal sight rules to your enemies on their turn.

If you turn your searchlight to iluminate someone but you fail your sight test so don't light up the enemy are you still iluminated

[Nabterayl]

No, you aren't. The searchlight isn't "turned on," if you want to think of it that way, until the firing vehicle has actually seen the target. You don't have to hit the target to illuminate it (and be illuminated), but you do have to actually take the shot.

If you want to think about what's actually "happening," the vehicle isn't sweeping its searchlight over the battlefield looking for a target, it's looking for a target and then hitting it with the searchlight and its weapons at the same time (which, not that this matters to what the rules say, is probably a smarter move than flailing around with your searchlight anyway).