Guide to Aids to Navigation for Boating

If you are boating on a small local pond or other less frequented location, you may not see navigation aids in the area. However, if you take to the water on a larger lake, channel or other busy waterway, you definitely need to know what navigation aids are, how they work and what they mean.

What are Aids to Navigation or ATONs?

Aids to Navigation (ATON) are external devices and systems that help boaters navigate safely on waterways by providing information about position, course, and potential dangers. These include buoys, beacons, lighthouses, and other markers that function like “street signs” on the water, helping boaters determine their location, identify safe routes, follow boating navigation rules and avoid obstacles.

The U.S. Aids to Navigation System

The U.S. Aids to Navigation System (USATONS) is meant to be used along with nautical charts. While external visual, audible and radar markers are key to identifying isolated dangers and giving other signals, they are not in and of themselves enough. Nautical charts provide essential information about water depth, permanent hazards and other features. 

The U.S. Coast Guard is responsible for maintaining aids to navigation on federal waters, while states maintain aids on non-federal waters.

It is also possible for a private group or individual to place an aid to navigation to mark a privately maintained waterway or zone, in which case they musk seek official approval and be fully responsible for maintaining the aids. 

Types of Aids to Navigation

Most aids to navigation fall into one of two main categories:

Buoys

Buoys are floating aids moored to the seabed, conveying information through shape, color, or symbols. These can come in various shapes and, including nun buoys (cylindrical shape with conical top), can buoys (cylindrical shape with flat top), lighted buoys and unlighted buoys.

Beacons

Beacons are permanently fixed structures ranging from lighthouses to small, single-pile structures, located on land or in water. Lighted beacons are called lights, and unlighted beacons are called daybeacons. 

Both types of navigational aid may be referred to as marks (more technical) or markers (everyday use). 

Navigational aids also include some types of radio signals, radar and sound signals (such as a gong, bell or horn).

They also include lateral and non-lateral markers:

Lateral Markers

Lateral markers are port-hand markers (red) and starboard-hand markers (green).

Non-Lateral Markers

Non-lateral markers include safe water markers, isolated danger markers, and special purpose markers.

Note: Markers are not necessarily 100% accurate. While the Coast Guard does everything possible to keep them in good condition and placed correctly, never assume that they are completely reliable. Always exercise caution. 

The Red Right Returning System

There are different navigation systems in use in different parts of the United States, but the most common and widespread is the Lateral or Red Right Returning System.

In this system, when navigating inland from the sea, red even-numbered markers are on the starboard side (right side) of the channel. Green, odd-numbered markers are on the port side (left side) of the channel. 

The numbers on the markers get higher as you travel inland. 

With this system, it is possible for boaters to determine whether they are going further inland or further out to sea, even if they are disoriented, lack a compass, or have another type of navigational equipment failure.

Other Types of Aids to Navigation

Pleasure craft operators in the U.S. may not see the following types of markers as frequently as buoys and beacons. It is still a good idea to be familiar with them, so that you remain alert and aware of any important signals in the area where you are boating. 

Dayboards

Diamond-shaped dayboards are navigational aids that pinpoint a vessel’s position on a nautical chart. By identifying the dayboard and locating its corresponding symbol on the chart, pleasure craft operators can determine their precise location. These dayboards may be lettered for identification and can be equipped with a white light. Their color typically corresponds to the color of nearby lateral markers (e.g., red or green).

Safe Water Marks

These navigational markers identify fairways, mid-channels, and offshore approach points. They are situated in areas surrounded by unobstructed water, may be identified by letters and may be equipped with a white light. They may also feature a distinctive red top mark.

Isolated Danger Marks

These navigational markers warn of a danger that can be safely passed on all sides. They are positioned directly on, or moored near, the hazardous area. Mariners should exercise extreme caution when navigating near these markers. They may be equipped with lights and may be identified by letters.

Special Marks

Special marks do not help you determine which side of the waterway you are on (i.e., they lack lateral significance). These buoys are used to delineate specific areas or features, such as anchorage zones, fishing grounds, or dredging/spoil disposal sites. They may feature a fixed or flashing yellow light. While their shape is not standardized, they are often the same shape as any nearby navigational buoys.

Mooring Bouys

Mooring buoys are key for securing vessels. They are the only designated buoys for legally tying a vessel. They come in two main shapes: sphere and cylinder. Both types feature a distinctive white body with a solid blue horizontal band at their center. Mooring buoys may be equipped with a white reflector or a white light for enhanced visibility. They are typically found within marked anchorage areas, and mariners should exercise caution when navigating near these zones. Refer to your state’s boating guide for specific operating restrictions within designated anchorage areas.

Regulatory Marks

Regulatory Marks are designed to guide boaters by alerting them to specific restrictions or hazards. These marks typically consist of white “can” buoys adorned with orange shapes. The shape of the orange symbol conveys a particular meaning, providing either a warning or instructions for safe navigation.

• Open Diamond: Indicates a potential danger.
• Diamond with Cross: Signifies an exclusion area that must be avoided.
• Circle: Warns of upcoming operational restrictions, such as speed limits.
• Square or Rectangle: Provides specific navigational instructions.

Ranges

Range markers are navigational aids designed to help mariners maintain a specific course within a channel. They can be lighted or unlighted and, when observed in a line, indicate that the pilot is on the centerline.

Uniform State Waterway Marking System

The USWMS is a separate system from ATONs, and since 1998 is no longer in use. It used very different markers from the ATONs system, and any remaining markers from this system ill be very hard to interpret correctly. If in doubt, contact the local Coast Guard for assistance. 

The U.S. Coast Guard provides several ways to get assistance:

1. Phone Options:

• Call the Coast Guard National Command Center at 1-202-372-2100 (available 24/7)
• Contact your local Coast Guard station (find their number online)

1. Emergency Communication:

• Use VHF Radio Channel 16 for immediate assistance
• Dial 911 in maritime emergencies

1. Additional Contact Methods:

• Email through their website at uscg.mil/contact
• Visit a local Coast Guard station in person
• Use their online contact forms for maritime safety inquiries

When contacting them, be prepared to provide:

• Your specific location
• Details about the marker you cannot understand
• Any relevant navigational context

The Coast Guard’s primary mission includes maritime safety, so they are well-equipped to help boaters with navigational questions and concerns.

Do pleasure boat operators need to be familiar with Aids to Navigation?

Yes, pleasure boaters need to be familiar with Aids to Navigation (ATONs). Understanding ATONs is crucial for safe navigation on waterways. Here’s why:

1. Safety: ATONs help boaters identify safe routes, avoid hazards, and navigate channels safely.
2. Legal requirement: In some jurisdictions, pleasure craft operators are required to carry up-to-date nautical charts, which are used in conjunction with ATONs.
3. Navigation assistance: ATONs provide information similar to road signs, helping boaters determine their position, course, and potential dangers.
4. Diverse waterways: ATONs are used in various water bodies, including rivers, lakes, and coastal areas, making them relevant for all types of pleasure boating.
5. Night navigation: Many ATONs have lights or reflective properties, which are essential for safe boating after sunset or in low visibility conditions.
6. Regulatory information: Some ATONs convey important regulatory information, such as speed limits or restricted areas

Learn about aids to navigation and more from Drive A Boat USA

Familiarizing oneself with ATONs is an essential part of boating education and contributes significantly to maritime safety for pleasure boaters.

When you take a state-specific safe boating course, you learn everything you need to know to take to the water safety and legally in your state, including the so-called rules of the road.