Aids to Navigation
How to Read a 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. The RW "G" means that it is a Red and White striped marker with, in this case, the letter "G" on it.
A lighted marker flashes at night and during restricted visibility. The next marker you see as you enter this waterway is the G "1" Fl G 4 sec. This tells you it is Green, has the number 1 on it, and it Flashes Green once each 4 seconds.
R N "2" plus the red symbol indicates a Red Nun buoy with the even number 2 on it. Conversely G C "3", is a Green Can buoy with the odd number 3 on it.
When entering from seaward you may find two channels which separate and go in different directions. A junction marker referred to as RGN "C" uses its top color to show you the major or primary channel. This is represented by a Red and Green Nun buoy with (in this case) a "C" on it. 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 Red Nun to the right. To take the secondary channel, use the bottom color.