AIS-enabled man-overboard beacons for sailors

A personal MOB beacon using the AIS system ups the safety factor for sailors

Andrew Taylor was working the foredeck of Derry-Londonderry-Doire, a competitor in the 2014 Clipper Round the World Race, on a stormy day in the Pacific when his worst fears became reality. “At some point, the boat moved pretty dramatically,” Taylor said. “The boat went down, and when it came back up, I wasn’t onboard anymore.”

Taylor survived in the near-freezing Pacific waters and gale force winds for an hour and a half before he was found by his crew and hoisted back aboard. The key factors in his survival were the seamanship of the 65ft yacht’s skipper and crew, the dry suit that kept hypothermia at bay, and— crucially—his AIS man-overboard beacon.

AIS (automatic identification system) is a method of tracking vessels via GPS and sharing this info publicly over certain VHF radio channels. The VHF channels 87B and 88B are reserved for transmitting and receiv- ing digital data. These transmissions are automatically generated and received by dedicated AIS equipment onboard every commercial ship and many recreational vessels. An onboard chartplotter, tablet or computer receives information from this AIS device. When your AIS equipment receives the data from other AIS-equipped vessels, small triangles are placed on your chartplotter screen to indicate where the other vessels are. With such information on your screen, you’ll have greater situational awareness and an increased chance of avoiding collisions. If you’re going to invest in an AIS MOB beacon, you must have an AIS transceiver or receiver installed on the vessel you are sailing on.

AIS is a great safety feature for cruisers, and its usefulness has been expanded by the increasing availability of personal AIS man-overboard beacons—small devices that can be attached to a lifejacket. They receive position data via an internal GPS antenna and transmit that data on the AIS VHF channels to any vessel within range. Upon receiving the signal from your AIS MOB beacon, your AIS-enabled chartplotter (or a smart-

to realize that a crewmember has fallen overboard, and they certainly will not be aware of your position once you’re out of sight.

An AIS beacon radically increases your chances of survival, since the vessel closest to you is the one you’ve just fallen from.

CHOOSING AN AIS MOB BEACON

I’ve recently reviewed some of the most popular devices on the market. Here are a few of the things you should look for.

First, check out the transmit range. Some manufacturers have listed a transmit range of 4 miles for these beacons, while others have boasted as much as 10 miles. It’s important to remember that these are transmitting over VHF, whose range is line-of-sight. The height of the receiving antenna and the prevailing wave conditions will have a big impact on transmission range.

Then there is the question of DSC (digital selective calling). DSC is a feature built into modern VHF radios that, among other things, allows for private radio calls between vessels. DSC also has a distress feature that, when activated, will trigger an alarm on the radios of all nearby DSC-equipped vessels. Some AIS MOB beacons will trigger a DSC distress call as well. That said, some of this functionality varies by region, and unless you already have one you’ll also need to acquire and enter an MMSI number. So before buying a beacon for its DSC feature, be sure to do your homework.

SUMMARY

Although AIS beacons are currently the only way for an MOB to be directly located by nearby vessels, they are not a complete solution. With worldwide coverage from satellites, PLBs offer direct alerting of rescue services, which will then initiate search-and-rescue operations. Most PLBs also transmit a signal on the 121.5 Mhz emergency aircraft radio frequency. This feature can further aid rescuers in locating the victim.

Considering that PLBs and AIS beacons work on different principles, wise offshore sailors will actually fit their lifejackets with both types of device. Ah, you ask, but why isn’t there a unit that combines the functionality of AIS beacons and PLBs? Perhaps we don’t have much longer to wait. Not yet on the market, but listed as “coming soon,” is the Seaangel SA16+. Nearly identical to the company’s AIS Eco Flare, this device will function as both an AIS beacon and a PLB. Could this two-in-one product be the first of a new generation of lifesaving personal distress beacons? s

Phillip Gutowski, a regular contributor to SAIL, owns a Tayana Vancouver 42 and runs BoatRX (boatrx.com), a marine systems installation business.