ASA 105: Skill 7, Aids to Navigation, Unlighted marks


7.Explain the significance of shapes, colors, and lights used in the U.S. Aids to Navigation (ATON) system.



Nun buoy
Conical top is a requirement for nun buoys.  If marking a channel they have even numbers are red in color and are left to starboard when entering, port when departing.



Ready references include:
Chart One, Page 125 
Eldridge 2022, Page 214
Boat Navigation for the Rest of Us, inside flaps and back cover

Shapes and colors are important for day piloting.  Lights on buoys are often correlated to the color of the buoy itself.

Nuns have conical tops.  Red nuns with even numbers are lateral marks denoting the left side of the channel when heading seaward.  Nuns are not lighted.

Cans have cylindrical tops.  Green cans with odd numbers denote the right side of the channel when proceeding seaward.  Cans are not lighted.

Tower buoys may have a sound signal or a light or both.  The color denotes the buoy's significance.  Red or Green tower buoys are not called nuns or cans.


Green lighted bell buoy.  The conical shape is note related to the fact the mark is green.  
It is not a "can" buoy but a green lighted bell buoy.  Tower buoys such as this may have no sound signal, a whistle, horn, gong or bell sound devices.  They may have a light or not.



Beacons are structures on land or grounded in the sea.  They may be lighted or not.  

In the waters of the USA green marks are kept to starboard when departing a harbor.  Red marks are kept to port when departing.  A quick memory aid is "red right returning."  Red and white vertically striped buoys are kept to port entering or exiting a harbor.  By definition, in coastal waters, you are entering a port when the current is flooding, i, e., traveling with you, in your direction.

Note:  In 1980 the US Coast Guard changed from Black buoys to Green buoys.  Chart 1210 Tr was first printed well before 1980 and has not been updated with new buoyage or color identifications.  Buoys painted back are not identified with a color.  Where we might now see G "1" Fl G 4 sec Gong pre-1980 the identity would be "1" Fl G 4 sec Gong.  Lights that are White are not marked with a color on the chart.


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