ATONs (Aids to Navigation)

Justin CherniakCruising Skills ClassroomHoofer Sailing Club

Aids to Navigation

Items found on waterways to identify safe channels to pass

Buoys (floating) or beacons (fixed) Meaning defined by combination of

shape, color, number and sometimes light pattern

Lateral Marks Indicate the left and right sides of a channel “Red, right, returning” – keep red on right side

when going from larger smaller body of waterLeft side

• Flat top• Cans – flat cylinder• Square day mark

• Green colored• Odd Numbers• Indicate left side of channel

when returning from sea

• Right side• Pointed top

• Nuns – conical shaped buoy

• Triangle day mark• Red colored• Even numbers• Indicate right side of

channel when returningfrom sea

Other marksSafe-Water Marks Junction Marks

• Used to indicate the center of a channel (from seaward approach)

• Can be approached from all sides

• Red and white stripes• Unnumbered (although

sometimes lettered)

• Indicate a fork in the channel• Unnumbered (although

sometimes lettered)• Red and green striped• Red top - treat as red lateral

mark• Green top– treat as green

lateral mark

Mooring Buoy Isolated Danger Mark• Indicate a mooring area• Can be used to attach boats• White with blue top

• Indicates a danger that should be avoided but can be passed on all sides

• Black and red with 2 balls on top

Regulatory Marks

Indicate some sort of danger or other regulatory measure

White with red stripes An open diamond shape signifies danger. A diamond with a cross in it signifies an

exclusion area that you may not enter.• A circle indicates an

upcoming operating restriction, such as a speed limit or no wake zone

• A square or rectangular shape is used for conveying instructions or information

ICW - Intercoastal waterway Inland waterway that runs around

coast from North -> South and East -> West

Have yellow symbols on buoys that should be followed instead of traditional green/red

Square – keep ATON to port(like a green ATON)

Triangle – keep ATON to starboard (like a red ATON)

Example