Definition
A sector light uses coloured screens or filters so that a mariner sees white in the safe approach sector and red or green over hazards, red conventionally on the port hand seen from seaward. Sector limits are given on the chart as bearings from seaward toward the light, in degrees true. Sectors are quoted clockwise, and the boundary is not razor sharp: an arc of a degree or two of colour mixing is normal, so do not navigate on the cusp.
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