chart and publication secrets 15
Safe water all around
RW = red and white vertical stripes. Such a navaid is oft en called a
midchannel buoy, or beacon.Channel splits into two (one with deeper water)
RG = red and green horizontal bands (the top band being red). In
North America, keep the buoy to your right when returning from
seaward to stay in the preferred (deeper-water) channel.
GR = green-and-red horizontal bands (the top band being green). In
North America, keep the buoy to your left when returning from
seaward to stay in the preferred channel.Extreme danger nearby
BR = black and red horizontal bands.- What is the name? Smaller lights and all buoys are identifi ed with numbers,
letters (single or dual), or number-letter combinations bracketed in quotation
marks. Common examples might be the number “7,” letter “F” or “CB,” or a
combination such as “16E.”
Lateral aids are numbered from seaward (or in a clockwise direction
around North America), with the sequence beginning anew each time you
leave one cove, harbor, or channel and enter another. Green aids carry
odd numbers and red aids carry even numbers. Th us, the fi rst aid you
encounter when entering a channel, river mouth, or harbor entrance from
seaward will usually be numbered “1” if it’s green or “2” if it’s red. You
should closely track your position to prevent confusion. - What is the light pattern? A light pattern helps an aid stand out from
nearby lighted aids. Aids marking channels use one of four fl ashing
patterns. Each light pattern includes specifi ed intervals of light and
darkness, called a light period. Here are the abbreviations used to indicate
the light pattern. Look back at our sample light characteristic. Which one
of these standard characteristics describes it?
Fl = fl ashing (fl ashes at a set interval)
Q = quick fl ashing (fl ashes once per second)
Oc = occulting (light stays on longer than it stays off )
Iso = isophase (exhibits equal periods of light and darkness)
Our example buoy has a fl ashing 4-second light period. Th is means
its total period of light and darkness equals four seconds. You would
time the buoy from the fi rst fl ash of the pattern, to the fi rst fl ash of the
pattern’s next repetition. Check the timed period against that shown on
the chart.