For centuries, physical markers like buoys and beacons have guided vessels safely through waterways and around offshore hazards. These traditionally physical aids remain essential, but new digital technologies are beginning to complement—and in some cases replace—physical navigation markers. This article explains the evolution of these Aids to Navigation, also known as AtoNs.

What Are Aids to Navigation (AtoNs)?

For centuries, physical markers like buoys and beacons have guided vessels safely through rivers, harbors, and coastal waterways. Painted in bright colors and anchored to the seabed, these familiar floating markers identify safe channels and warn of hazards such as bridge clearances or channel edges. They also provide important navigational information, directing commercial and recreational traffic.

Aids to Navigation (AtoNs) include lateral channel markers, cardinal marks, isolated danger markers, beacons, leading lights, buoys and more. Lighthouses are perhaps the most distinguishable AtoNs through the centuries.

The Challenges of Physical Buoys

As rugged as these physical markers are, they operate in harsh marine environments, and their longevity is impacted by the natural forces that surround them. Every year they are exposed to high water and flooding, ice movements, hurricanes and severe storms. Additionally, they face vessel collision, corrosion, mooring failures, and the impacts of debris.

The U.S. Coast Guard regularly receives reports of buoys that have drifted off station or have been damaged by weather or vessel strikes. For waterways experiencing rapidly changing conditions, physical markers can become outdated almost as soon as they are installed. Maintaining this network requires continual inspections and specialized buoy tenders operating throughout the year.

More importantly, any damage they suffer can mean real-time consequences for those offshore. For example, when a buoy is knocked off station or disappears entirely, it can no longer accurately mark the navigation channel. The result can mean life or death for vessels relying on the markers to avoid hazards. In some situations, immediately replacing a buoy may be impossible because conditions are too dangerous for maintenance crews.

With AIS technology and electronic AtoNs, that is beginning to change.

Enter the AIS AtoN Buoys – virtual, synthetic, real

As Mark Wiggins and Greg Johnson write, Automatic Identification System (AIS) technology has “traditionally been used to broadcast vessel position, course, speed, and other vessel information to nearby vessels and shore authorities such as Vessel Traffic Services (VTS).”

Thanks to advances in AIS, traditional AtoNs have received an upgrade. AIS AtoNs (Automatic Identification System Aid to Navigation) can use AIS to create electronic navigation markers visible directly on AIS-enabled chart plotters and Electronic Chart Display Information Systems (ECDIS). This is the same radio-based technology that commercial vessels use to broadcast their identity and position. Now, AIS AtoNs are doing the broadcasting.

Within this new family of AIS AtoNs, there are three types: virtual, synthetic, and real. Unlike a physical buoy, a virtual buoy is non-physical and exists only electronically. The virtual AtoNs AIS signal is sent from another (usually land-based) location, but to the vessel operator, it appears on their navigation display exactly where it is needed. Synthetic AIS AtoNs are physical but without an AIS transmitter. Synthetic AIS AtoNs’ AIS messages are sent from another location. Last, the Real AIS AtoN’s are a physical navigation aid on which an AIS transmitter is mounted and from which AIS messages are sent.

One example of this AIS AtoN technology is the easyAToN Type 1 AIS transmitter developed by Weatherdock. The device enables operators to broadcast AIS AtoN signals that appear directly on vessel navigation systems in real-time, providing a flexible solution for marking hazards, offshore installations, and navigation zones. The unit can create “synthetic,” “virtual,” or “real” electronic navigation marks that appear on AIS capable electronic chart plotter or navigation PC-software. With reliable AIS transmission, durable design, and easy install, the easyAtoN is ideal for temporary or permanent navigation marking.

Virtual Doesn’t Mean Physical Buoys Are Disappearing

Despite the excitement surrounding virtual navigation aids, they are not intended to eliminate physical buoys altogether. Many recreational boaters still rely primarily on visual navigation. Likewise, not every vessel carries AIS equipment capable of displaying electronic navigation markers. For this reason, the Coast Guard (USCG) and U.S. Army Corps of Engineers (USACE) view Virtual AtoNs as an additional layer of navigational awareness rather than a complete replacement for conventional buoys.

Without needing to replace every buoy on the water, the use of AIS Aids to Navigation can create a smarter navigation ecosystem where physical and electronic aids work together.

Read more about the Advantages of Electronic Navigation Aids and contact us to learn about the Weatherdock easyAtoN Type 1.