its not just the brightness of the lights. Navigation lights must be installed correctly. they tell a driver which direction another approaching boat is heading... The green should be visible up to a certain angle and just the same with the red. I am sure most of us here know this. But I wonder about some people. The worst for me are the pontoons with the bright white (headlights) you can not tell which direction they are going, I really wish they would check lights at these little working man tourneys just like a live well check. its crazy how many boaters have one or the other light, not both.