How to Read Buoys and Channel Markers: Red Right Returning and the U.S. Aids to Navigation System

Lateral marks are arranged for a boat returning from sea, heading upstream or toward the head of navigation. Where there's no clear "from sea," the direction generally runs clockwise around the U.S.: southward along the Atlantic coast, westward from Florida to Texas along the Gulf coast and northward along the Pacific coast (33 CFR 62.21). On lakes and in confusing areas, the chart tells you.

When you're returning (going in the conventional direction), keep the red marks on your right (starboard) side and the green marks on your left (port). Heading out to sea (or downstream), it's the reverse: red on your left. Picture the channel as a road with red curbs on the right as you come home.

• Red marks (starboard hand): buoys are nuns, with a tapered cone-shaped top, or pillar buoys; daybeacons have red triangular daymarks.
• Green marks (port hand): buoys are cans, cylindrical, or pillar buoys; daybeacons have green square daymarks.

The shape matters at dawn, dusk or in glare when color is hard to see, and it's the same meaning in both IALA regions. Pillar buoys (a wide base with a framework tower, often with a light, bell or horn) carry the meaning in their color.

Solid red aids carry even numbers and solid green aids carry odd numbers, and the numbers increase as you go in the conventional direction (in from sea). Numbers are kept roughly in step on both sides, so some may be skipped. A letter suffix (like the "2A" on the cover photo) marks an aid added to an existing sequence or the first aid of a waterway (33 CFR 62.43). If the numbers are going down, you're heading out.

On lateral aids, green lights mark the port side and red lights the starboard side of the channel when returning, with a regular flashing (or occulting) rhythm. A quick flashing light (about 60 flashes a minute) warns of a sharp turn, sudden narrowing, wreck or obstruction. White and yellow lights have no lateral meaning (except on the Western Rivers, step 10); read the aid's shape, color and number instead. Some lights show different colored sectors over hazards, shown on the chart; treat sectors as a warning, not an exact bearing (33 CFR 62.45). Your chart lists each light's color and rhythm, and a spotlight helps you read numbers and reflectors. See our night boating guide.

Where a channel splits, or a wreck can be passed on either side, you'll see a mark with red and green horizontal bands. The top band's color tells you the preferred (main) channel:

• Green on top: treat it as a green (port hand) mark to follow the preferred channel when returning; it's a can or pillar buoy or a square daymark.
• Red on top: treat it as a red (starboard hand) mark for the preferred channel; it's a nun or pillar buoy or a triangular daymark.

Lit preferred channel marks show a composite group flash (two flashes then one), in the color of the top band (33 CFR 62.25 and 62.45). Check the chart before you choose the secondary channel.

• Safe water marks: red and white vertical stripes. Navigable water all around; they often mark a fairway, mid-channel or the seaward end of a channel. Buoys are spherical or carry a red ball topmark; daybeacons have an octagonal daymark. Lit ones flash white Morse code "A" (short-long) (33 CFR 62.27 and 62.45).
• Isolated danger marks: black with red horizontal bands and two black balls on top. They sit on or near a danger that can be passed on all sides, but don't approach closely. Lit ones show a white group flash of two (33 CFR 62.29).
• Special marks: solid yellow. Not for navigation; they mark anchorages, cable or pipeline areas, military or research areas and similar. Check the chart (33 CFR 62.31).
• Mooring buoys: white with a blue horizontal band (33 CFR 62.35).

These are the markers you'll see most on lakes and near shore: white buoys or signs with orange shapes (33 CFR 62.33):

• Open diamond: danger (rocks, shoals, dams, stumps); the hazard is often written inside.
• Diamond with a cross inside: boats keep out (swim areas, dams, spillways).
• Circle: operating restrictions, such as slow/no wake, speed limits or no PWCs; the rule is written in the circle.
• Square or rectangle: information, such as directions, distances or where to find fuel or food.

A regulatory buoy is white with two orange bands, one near the top and one just above the waterline. On some inland state waters you may also see a black-and-white vertically striped buoy: it means an obstruction extends from the nearest shore to the buoy, so don't pass between the buoy and the shore (33 CFR 62.32).

Along the ICW, aids carry yellow symbols in addition to their normal colors (33 CFR 62.49):

• Yellow triangle: keep the aid on your starboard (right) side, regardless of its color or number.
• Yellow square: keep the aid on your port (left) side, regardless of its color or number.
• Yellow horizontal band: identifies an ICW aid but gives no side information.

These meanings apply when going south along the Atlantic coast and west along the Gulf coast (and westward on the Okeechobee Waterway). Where the ICW shares a stretch with a channel that leads in from sea, the regular red and green may say one thing and the yellow symbol the other: if you're following the ICW, follow the yellow symbol.

On the Mississippi River and its tributaries above Baton Rouge, and certain other rivers flowing to the Gulf, the Western Rivers Marking System applies (33 CFR 62.51):

• Buoys aren't numbered.
• Numbers on beacons show river mileage from a fixed point (usually the mouth), not port/starboard.
• Diamond-shaped crossing dayboards (checkered red-and-white or green-and-white) mark where the channel crosses from one bank to the other.
• Lights on green buoys and green-daymark beacons show a single flash (green or white); on red ones, a double flash (red or white).
• Isolated danger marks aren't used.

River channels also shift with water levels, so check local notices and river charts.

The Coast Guard warns that buoy positions on charts are approximate, buoys swing on their moorings within a "watch circle," and storms, ice, current or collisions can move, sink or capsize them (33 CFR 62.23). Sound signals on buoys (bells, gongs, whistles) are driven by the waves, so they may be silent in calm water, and you can't judge distance by how loud they sound (33 CFR 62.47). Cross-check every buoy with your chart, depth sounder, GPS and landmarks.

Federal law prohibits tying up to, damaging, moving or otherwise interfering with a Coast Guard aid to navigation, with fines and possible jail time (33 CFR 70.05-1 and 70.05-5). If you hit one, report it; the rules require a report. If you notice a buoy missing, off station or a light out, tell the Coast Guard (for example on VHF channel 16 or through the Navigation Center site) so others don't get hurt.

How to make a useful report. The Navigation Center has an online ATON Discrepancy Report form. It asks for your contact details, the state, the aid's name as listed in the Light List, and what's wrong (a lighted aid that's out or flashing wrong, or another problem such as missing, damaged or off station). Before you report, note the aid's number and color, your GPS position and the time, and snap a photo if it's safe. If a missing aid leaves a real hazard (a wreck or rock with no mark), call the Coast Guard on VHF 16 right away instead of waiting for a form.

Check the weekly notices before a trip. Each Coast Guard district publishes a weekly Local Notice to Mariners on the Navigation Center site, listing aids that are discontinued, relocated, damaged or temporarily changed, plus dredging, bridge work and marine events. Skim your district's latest notice before a long run in unfamiliar water; a buoy that "isn't where the chart says" is often already listed there.