USCG rules
The USCG rules say:"When anchored outside of a special anchorage, power and sail vessels under 20 meters [65.62 feet] need to display an all-round light. Vessels under 7 meters [22.97 feet] are exempt, unless anchored in a narrow channel or anchorage, or where other vessels usually navigate." "All-round lights are white and shine through 360 degrees." "Visibility Range - 2nm "(as per the West Marine Catalog's West Advisor)There's probably a USCG site somewhere, but I remembered seeing this when shopping last week. I just copied it out of the catalog.