Aids to Navigation
Unlike the roads and highways that we drive on, the waterways we go boating on do not have road signs that tell us our location, the route or distance to a destination, or of hazards along the way. Instead, the waterways have Aids To Navigation (or ATONs), which are all of those man-made objects used by mariners to determine position or a safe course. These marks are also indicated on your chart.
The term "aids to navigation" includes buoys, day beacons, lights, lightships, lighthouses, radio beacons, fog signals, marks and other devices used to provide "street" signs on the water. Aids to navigation include all the visible, audible and electronic symbols that are established by government and private authorities for piloting purposes. To help you understand what these mean, the basics are presented here.
Port Side Odd Numbered Aids
These Naval Aids are numbered with odd numbers, are green in color, and may be lighted (will have a green light). Port side marks are located on the left side of the waterway as you travel upstream, and the buoy numbers will increase as you head upstream. (Chart depictions are shown next to the marks) Port-Side Buoys have a cylindrical above-water appearance, like a can or drum floating on its axis. Commonly referred to as "CAN" buoys. Beacons - Port side beacons have square marks attached to them, with two shades of color and a reflective border.
Starboard Side Even Numbered Aids
Starboard aids are red in color, evenly numbered, and will be on your right side as you travel upstream. Buoy numbers increase as you head upstream, and may have a red light. Starboard-side Buoys have an above-water appearance like that of a cylinder topped with a cone, pointed end up. The cone may come to a point or be slightly rounded and are commonly referred to as "NUN" buoys. Starboard-side Beacons have triangular marks attached to them, with two shades of color and a reflective border.
Regulatory Marks & Aids
Regulatory marks are designed to assist boaters by informing them of special restrictions or dangers that they are approaching. Regulatory marks are white "can" buoys that have an orange shape on them. The mark will give either a warning or instructions on how to proceed. The shape determines what type of mark it is.
A square or rectangular shape is used for conveying instructions.
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.