AUTOMATIC IDENTIFICATION SYSTEM — N
CRUISING CLUB OF AMERICA
ow more than ever, the modern sailor has lots to choose from when it tempting to not worry about what you comes to navigation and safety instrudon't see. You can get blinded." ments. Communication devices such as With the advent of AIS and other the Iridium GO! and Garmin inReach devices, we recognize that the modern (which also has GPS capabilities) have mariner must learn an increasingly complemented the single-sideband radio and VHF. Chartplotters have digitized and dramatically simplified navigation, and radar has long been an important tool for identifying marine traffic, obstacles and weather. One of the more recent advances is the Automatic Identification System, or AIS, which has dramatically changed the way sailors observe and identify marine traffic. "AIS is one of the most significant marine safety innovations in a decade," said the Cruising Club of America (CCA). Relatively cheap and able to piggyback onto a boat's VHF antenna, AIS has helped cruisers manage harrowing passages in low visibility through invisible elec- Its utility is perhaps best expressed by its simplicity. AIS can piggyback off trical pulses transmit- your VHF, and is available on small beacons in case of a crew overboard. ting where you are, and delicate balance between utilizing the where everyone else is in relation to you. advantages of technology and maintain"It's a tremendously valuable tool ing their 'analog' skills for when (not if) that we didn't have 10 years ago," said something goes wrong. Frank Cassidy, the author of the CCA's There are two classes of AIS: 'Class AIS: Overview and Installation ConsiderA' is designed for commercial vessels, ations. "It used to be that at night, you is higher powered, and comes with a had to look for lights with your binocudisplay and keyboard. The majority of lars and quickly determine what they cruisers use 'Class B', which is 'interopmeant and what direction the ship was erable' or can transmit and receive with going. But AIS tells you everything." Class A units. But, like every maritime advance"Class B transmits position every 30 ment, a gizmo that starts to do the work seconds, is available as a 'black box' of a sailor has the potential to erode that
"The Automatic Identification System (or AIS) is one of the most significant marine safety innovations in a decade." sailor's seamanship skills. AIS, which is absolutely not required and by no means ubiquitous on the millions of boats throughout the world, may potentially lure sailors into a false sense of security. "I'm worrying about the targets I can't see," Cassidy said. "Because it's very Page 90 •
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without a display, is affordable, and is all that most pleasure boats need," Cassidy's CCA article said, adding that Personal AIS Beacons — sometimes called PABs — are available for life jackets in the event of a crew-overboard situation, something that offshore races, such as
the Transpac, are starting to require. Cassidy said he wrote the article because of two diverging opinions about installation revolving around choices about antennas. As mentioned, AIS will work off a boat's existing VHF system — but that requires some compromise of power, What's more, AIS signals stop transmitting when the VHF is in use. One school of thought is to have a second antenna for AIS, thus eliminating the VHF compromise and creating some redundancy. But having two antennas on most sailboats requires its own set of compromises, as most experts believe that electric aerials should be at least four feet apart, space that's not easy to find atop a skinny mast. One solution is to use a horizontal bar, with each antenna mounted at the end. "Another temptation would be to put an antenna on a spreader, but then it's between a stainless-steel shroud and mast," Cassidy said. "If you have a sloop, most people end up putting their second antenna on a pole off the back of the boat. Effectively, you're creating a second mast." Having a ketch, yawl or schooner obviously eliminates the problem of second antenna placement that sloops are faced with. Which antenna, between VHF and AIS, should be higher? Cassidy said that it's important to have the VHF antenna as high as possible to increase its range, where as with AIS, you're most concerned about boats that are within a few miles of you, making range — and therefore height — less of a factor. Cassidy said the Cruising Club of America wanted to be careful not to 'dictate' what installation choices cruisers should make — rather, those decisions come down to idiosyncrasies of people's boats, their budgets, the type of cruising they plan on doing, etc. We thought the best review of AIS was from the sailors on the front line. We asked our readers to share their experiences with AIS. Here's what we heard:
