Marine Glossary

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sector light

A charted light that has more than one horizontal angular sector of visibility. The sectors are defined as bearings to the light from the vessel. On paper charts and the RNC based upon them, the printed light descriptions define the sector where the light is obscured, but on ENC the sector ranges (found by a cursor pick to the light) defines where the light is visible.

For sector lights there will not be a light description shown on the screen, so we must cursor pick the light to learn the digital values of the sector limits. These limits are drawn on the screen, usually as short lines (one inch or so), with an option to extend them out to the nominal range of the colors. Sector lights do not show the descriptions, likely because each sector usually has different descriptions and some lights have very many sectors, over a dozen in places.

Sector lights are marked with large rings (about 2 inches in diameter) marking the sectors.

Within ENC usage, a single color light with a sector of obstruction is now called a sector light, which eliminates a light description on the screen. This fact is one we must be continually aware of as some major lights show up without any description at all.