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How to Read a Nautical Chart

Nautical chart

Reading the chart on the left, the marker definitions are as follows: 


The first marker you see entering from sea is the open, or safe water, marker. A lighted marker flashes at night and during restricted visibility.

Safe water marker - Fairway marker

The next marker you see as you enter this waterway is the port buoy. This tells you it is Green, has the number 1 on it, and it Flashes Green once each 4 seconds.

Green buoy

Junction marker

When entering from seaward you may find two channels which separate and go in different directions. A junction marker uses its top color to show you the primary channel. This is represented by a Red and Green buoy. You use the top color and shape as if it were a stand alone marker if you want to follow the primary channel. In this case leave the green junction buoy to the left. To take the secondary channel, use the bottom color.

Junction buoys

Nun buoy and Can buoy

Red Nun buoy with the even number on it.

Starboard Red Nun Buoy

Green Can buoy with the odd number on it.

Port Green Can Buoy