The question is
whether the lights you're using meet the requirements of the rules for electrical nav lights in 33 CFR 84. That's what's required. There are different legal visibility requirement in 33CFR 84 for "powerboats" vs. "sailboats", as sailboats when heeled will not display the lights at the same angle as a powerboat steaming flat will, so the rules require a sailboat meet the minimums over a wider range of angle than powerboats, and that's where the Perko and other LED nav lights have a problem. With the more highly directional characteristics of LEDs, the LED lights meet the visibility required when the boat is flat, but not when heeled, so they're OK for powerboats but not sailboats. I use the Perko LED running lights, since almost invariably my night time travel is under power. If I am sailing at night, I'm aware that I'm not meeting the technical legal visibility requirements, and make allowances for that by keeping an eye out and presuming I may not be seen from all angles. But the Perko LEDs are many times brighter and visble from a much greater distance than my old incandescents, and use 1/10 the power. For practical purposes, it's only an issue in the event of a collision.