Considering the anchor light should be shown 360 degrees... Last year I was anchored behind another boat that had a light hanging in the foretriangle. It was a breezy night, with little wavelets on the water. It was easy to see the shadow cast by the mast, and it was a considerable size shadow. Obviously, the farther the shadow went, the wider it became.As the boat swayed back and forth with the breeze, the light came and went. So if you are thinking one light hung on the boat can be seen from everywhere, don't bet the Coastie that hands you the ticket that it's "Perfectly legal". A few years ago Boot Harbor in the Keys ticketed everone using a solar light hanging from the boom, but they said it was not a 2-mile certified light. Two miles visibility in a harbor maybe 1/4 mile across? The law is the law, no matter how much sense it makes.