We attached the lights to a Type II PFD and held them just above the water. Spotters re- ported whether they were visible at 1, 1.5 and 2 nautical miles.

If there’s a quick lesson to be learned about personal lights–the kind you have strapped or pinned to your PFD for when you fall overboard–it’s this: Only fall overboard on a dark, clear, calm night with no ambient light near the surface of the water. And stay close to the boat.

Truly there’s an almost infinite variety of conditions in which we might have to search for someone who’s fallen overboard. In any kind of chop (starting at less than one foot), your ability to see any light almost at the surface of the water is diminished greatly. Add inclement weather, lights along a shoreline, flashing navigation lights, your own…