When You're Adrift in the Sea

On May 9, when the Pacific Fleet's Vortex, with no one at the helm, ran aground on one of Mexico's isolated Revillagigedo Islands, passenger Peter Mesley, an expert tech diver from New Zealand, triggered his Personal Locator Beacon. Nearly 6000 miles away, the New Zealand Rescue Services picked up its signal via satellite. They contacted Mexican authorities and initiated an emergency rescue plan with the Mexican Navy.

A PLB is an essential device for diving in remote locations and should be in every liveaboard diver's kit. Depending upon where they are headed, land-based divers ought to give them a thought as well. There are two devices useful for divers.

Iridium satellite-based beacons, like the Garmin Inreach, allow rudimentary two-way conversation with a friend or rescuer by SMS text. It's a good device for people going to remote locations. Divers need a good holster to get it on a web belt. The Garmin is waterproof, but not to diving depths, and requires a $34.95 annual subscription. https://www.garmin.com/en-US/

Peter Mesley told Undercurrent he uses an Ocean Signal RescueME PLB1. Like the Garmin Inreach, when it's activated the RescueME PLB1 transmits your position and your ID to a Rescue Coordination Center via satellite link. Rescue services near you are promptly notified, and to assist rescue, are regularly advised of your current location. For diving, each needs a suitable waterproof container. https://oceansignal.com

The Nautilus LifeLine is probably the best for divers because it's designed to go to diving depths. Mike Lever, the owner of the Nautilus liveaboard fleet, created and brought it to market in 2011. The latest model features dual technologies: DSC and AIS.

Digital Selective Calling (DSC), essentially a line-of-sight technology (but may travel up to 34 miles), connects to nearby boats' VHF radio. Lever says DSC has been incorporated into every VHF radio, even handheld models, since 2003, so virtually any nearby craft with a radio will get your alert.

If someone presses the distress button on their LifeLine, the VHF radio on every nearby boat will automatically switch to channel 16; a horn or beeper will start chiming, a red light will flash, and the message "man overboard" with GPS location accurate to five feet will display on the face of the radio.

The LifeLine also uses Marine AIS (Automatic Identification System). The LifeLine transponder provides position, identification, and additional information about the diver. A signal can be electronically exchanged between AIS-receiving stations onboard ships or ashore via satellite.

Not every small boat has an AIS transceiver since only commercial ships, tugs, fishing boats, and larger yachts are required to have one. Some dive boats have them, and, as you would expect, that includes Nautilus vessels. They can pick up your signal, identify where you are, and track you down.

Lever calls it "amazing technology, simple, free to use with no special receivers, great range, and completely automatic. The fist-sized LifeLine weighs 4.6 ounces, has a 28-hour battery life in a stress mode, and retails for $199.

If you wish to carry a LifeLine into remote areas, there may be no other boats with an AIS transceiver, so first verify whether your liveaboard has one. If you were going to Cozumel, for example, and looked at www.MarineTraffic.com, you'll see that the big boats, like the ferries or cruise ships, seem to have AIS. But not the dive boats or other small boats. A DSC transmitter might be of little use if you were around the island's south end, more than a few miles from town, unless your boat is looking for you. That's where LifeLine's AIS technology comes in.

Most importantly, ensure you have studied the manual and understand how your LifeLine works. Ensure the boat skipper knows you're carrying one, so he or she will be prepared too. Of course, you can't test the effectiveness of your device until you actually need it. We hope you won't.

For more information on the Nautilus and to purchase one, click here, www.nautiluslifeline.com

P.S. The original (yellow) LifeLine used an in-built VHF radio but fell foul of international regulations because the user needed an MMSI (Maritime Mobile Service Identity) number. The user was required to obtain a Ship's Station License to get an MMSI number valid for international cruising. You can't get an MMSI number unless you have a ship's radio (i.e., own your own vessel). One liveaboard operator purchased such Lifelines for use by its passengers but found they were not robust enough to suffer the rigors faced by rental equipment.

- Roger Carlson and John Bantin