What Stripernut said! If we are talking slip lights, you need to consider leaving them alone. As he said, we pay a lot of money for that spot and even casting\catching fish in them can disrupt the bait for hours when things are tough. If we are talking overhead lights the marina's put out, then go for it.

Look at it this way... I'll concede that the water is public. But slip owners pay for the area all the way down to the water and you can't cast into that water without putting the bait in an area slip owners pay for.

I'll almost always purposely block my slip with my boat so the area can be uninterrupted.