AIS for Boaters: Part 1

“When was the most scared you’ve ever been aboard a boat?” I get asked that question a lot, and every single time I remember a cold November evening in 1994 when a 40-knot gale frothed up the mouth of Chesapeake Bay during a boat delivery to Miami, FL.

This screenshot shows the plethora of information an AIS transponder can provide. Screen shot courtesy of marinetraffic.com.

This screenshot shows the plethora of information an AIS transponder can provide. Screen shot courtesy of marinetraffic.com.

But it wasn’t the weather that was so unmanageable; it was the confusing mass of barely visible ship traffic that raised my blood pressure. Today, that same evening would have been much less stressful, thanks to a technology called the Automatic Identification System, or AIS for short.

 This AIS transceiver not only broadcasts information about the vessel it’s installed on, but receives information about other AIS-equipped vessels as well. Note the various targets on the display, represented as circles with direction marks. Image courtesy of Furuno.

This AIS transceiver not only broadcasts information about the vessel it’s installed on, but receives information about other AIS-equipped vessels as well. Note the various targets on the display, represented as circles with direction marks. Image courtesy of Furuno.

Back in ancient times (20 years ago, electronically), a radar blip was about all you could depend on to locate other vessels at night or in inclement weather, such as fog. And even then, you didn’t know what type of vessel you were looking at. Determining its speed and course? Well, that required some serious, practiced radar skills. Today, with an AIS receiver—or even a smart phone, tablet, or PC with a 3G cellular connection—you can find out just about everything you need to know about shipping vessels around you and where they’re headed.

Here’s how the whole system works: In the simplest of terms, an AIS unit broadcasts a VHF radio signal from a ship or other vessel containing the following information: position, course, speed, vessel name, type of vessel, and radio call sign. This information can then be received by any other vessel or land-based station with an AIS receiver. Typically, that information is overlaid onto an electronic chart, map, or other electronic graphical representation so the user can see where they are in relation to the other vessels in the area. The data is networkable with many different marine electronics devices including radars, VHF radios, and chart plotters.

This AIS screen shot shows all of the AIS-equipped vessels in the New York Harbor area. That’s a lot of ships! Screenshot courtesy of marinetraffic.com.

This AIS screen shot shows all of the AIS-equipped vessels in the New York Harbor area. That’s a lot of ships! Screenshot courtesy of marinetraffic.com.

While ships larger than 300 gross tons have been required to be equipped with Class A AIS systems since 2002, there are currently no laws requiring AIS on most recreational vessels. It begs the question, “So, why should I think about AIS for my boat?” Considering the fact that a large ship traveling at speed can be on top of your boat within as little as 15 to 20 minutes from the time you see it in ideal (note I said, “ideal”) weather, I ask, “Why not?”

You’re probably interested in what devices are available to access AIS on your boat.  Carry on to Part 2 of the article.

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