See and Be Seen

AIS­­—like any nav tool—needs to be used Wisely
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The benefits of AIS are many, and they start with the ability to identify a vessel by its name, position, course and speed.

The benefits of AIS are many, and they start with the ability to identify a vessel by its name, position, course and speed.

Calling the white-hulled motoryacht southbound in the vicinity of Point Lookout. This is Serenity, Serenity, Serenity. I am the northbound vessel under sail approximately 1 mile off your port bow making about 6 knots. Please come in on Channel 16, captain.” No response.

Before the advent of the Automatic Identification System (AIS), cumbersome and uncertain VHF radio attempts like the one above were typical. You had to start the communications process early if it were to do any good. You also had to imagine yourself as the intended receiver so he would think, Hey, that’s me. And even when you did make contact, there was the potential that you were coming to an understanding with the wrong vessel. Throw in darkness or fog, and the VHF radio could actually be the angel of confusion.

The benefits of AIS are many, and they start with the ability to call a vessel by its name. In addition, knowing the names of nearby boats can help make sense of radio chatter so you can understand what is going to happen next. In addition to vessel name, standard AIS information includes position, course and speed. That data comes automatically from a GPS; crew can manually input other information, such as vessel dimensions, destination and operational mode.

Information about other AIS-equipped vessels can be viewed on the unit itself, or on radar and electronic charts. AIS gives boaters a more complete picture of what is going on around them, which is always good—but it’s not the whole picture. There’s still the human component, which can include inputting erroneous information that other boaters receive.

I recall monitoring a westbound ship in the Caribbean in broad daylight while the AIS said it was heading east. I have seen vessels securely tied to the dock while the AIS proclaimed that they were underway, and vessels underway while the AIS indicated that they were at anchor. I witnessed a towboat in the Mississippi River transmitting its normal dimensions—a length and beam of 145 by 40 feet—but the barges it was pushing made the total space occupied 1,360 by 175 feet, bigger than some aircraft carriers. Imagine making a decision based on AIS data and then seeing that behemoth coming out of the morning mist.

In some parts of the world, there have been reports of fishing vessels attaching AIS devices to their nets, to shield them from other vessels running them over. Not only does this practice vastly increase the number of targets to interpret, but it also sows confusion as to what is a vessel and what is not. A darker example of AIS misuse occurred when a freighter ran down a fishing vessel in the English Channel, then switched off its AIS and continued on its way. The captain lost his license and paid a whopping fine.

AIS is valuable on any boat, but treat the 
information it displays with a dollop of skepticism and remember that boats not transmitting on AIS are not as noticeable as those that are.

AIS is valuable on any boat, but treat the information it displays with a dollop of skepticism and remember that boats not transmitting on AIS are not as noticeable as those that are.

What I find most interesting about AIS is its capacity to foster new patterns of human behavior and perception. For instance, people weaned on AIS won’t even attempt the protracted, old-fashioned VHF radio call. For them, if a vessel’s name is not onscreen, then the call is not made, and the window for action shrinks ever smaller.

Flipping that scenario around, a few years back, the Hyundai Dominion and the Sky Hope, both merchant ships with professional crews, slammed into one another in the South China Sea. It seems that the AIS texting function seduced these officers into thinking that they could avoid a collision by communicating, rather than by simply altering course or following the traditional rules of the road.

I have come to believe that non-AIS vessels are simply invisible to individuals conditioned to expect AIS. Something like this occurred recently when a cargo ship steered between a tug and a towed barge, nearly sinking both. The night was clear. The tug and barge were displaying proper lights. They had been visible on radar for nearly an hour. But neither was transmitting on AIS.

Thus, treat your AIS information with a dollop of skepticism, just like other information. And recognize that, rightly or wrongly, vessels not transmitting on AIS—especially smaller ones—may not be as noticeable as those that are. 

This article originally appeared in the July 2019 issue.