Getting personal with rescue


For mariners in distress, technology has significantly increased the chances of rescue. With modern electronic devices, from digital selective calling (DSC)-equipped VHF radios, to satellite phones, single sideband radios to cell phones, today’s mariners maintain closer communication ties with the shore and other vessels than ever before.

Also critical to the success of search and rescue (SAR) operations has been the introduction of a variety of electronic signaling devices such as Emergency Position Indicating Radio Beacons (EPIRBs), Personal Locator Beacons (PLB), Search and Rescue Transponders (SARTs) and personal Automatic Identification System (AIS) transponders.

EPIRB: One of the earliest electronic emergency signaling devices, EPIRBs have gone through two big stages of improvement. The first was the transition from early models that broadcast on 121.5/243 MHz (phased out on Dec. 31, 2006) to the more tightly regulated 406-MHz units. The second was the incorporation of GPS positioning into the EPIRB signal. This latter development makes the job of SAR teams much easier as they have a smaller patch of ocean to search.

Courtesy McMurdo

A GPS-equipped 406-MHz EPIRB.

EPIRBs work by transmitting to National Oceanic and Atmospheric Administration (NOAA) satellites. NOAA operates a series of Polar Operational Environmental Satellites (POES) and Geostationary Operational Environmental Satellites (GOES) that detect signals sent by mariners, aviators and land-based users in distress. These satellites along with a network of ground stations and the U.S. Mission Control Center in Maryland, are part of the Cospas-Sarsat system, whose mission is to relay distress signals to the international SAR community.

SART: While an EPIRB sends a radio signal to satellites, SARTs are designed to respond to radar signals. When a SART is turned on and receives signals at radar frequencies, it responds by transmitting a response on that same frequency. This response is displayed on the radar screen of a nearby vessel or search aircraft as a sequence of dots. These dots guide rescuers to the position of the vessel in distress or lifeboat.

PLBs: While an EPIRB is often intended to be associated with a vessel, a PLB is designed to be carried on a PFD.

In October 2002, the Federal Communications Commission granted a request by NOAA to permit the nationwide use of PLBs. The landmark decision meant that individual mariners as well as other outdoor enthusiasts could take advantage of satellite-aided search and rescue technology that was previously limited to shipboard and aircraft use.

The simplest of these PLBs transmit a 406-MHz signal when activated. When the person in distress activates the PLB (either manually or automatically) it transmits the digital 406-MHz signal to POES and GOES satellites. The signal is encoded with a unique identifier, which is relayed to a ground station, which processes the signal using Doppler technology to determine the location of the beacon so that SAR assets can respond. Accuracy for Doppler generated positions is within about two miles. For greater accuracy, many PLBs, like EPIRBs, are also equipped with GPS, which can provide an accurate position within about 100 yards. And, like EPIRBs, a PLB is also equipped with a low-power 121.5-MHz homing beacon for final position finding using radio direction finding equipment on Coast Guard vessels and aircraft.

Courtesy Kannad Marine

Personal AIS units can be clipped to life jackets.

PLBs purchased in the U.S. must be registered with NOAA through a simple process that can be done online, through the mail or via fax (see Some manufactures also offer enhanced subscription-based services, which include contact information and other details. The mandatory NOAA registration is free.

The market for PLBs has grown in recent years and manufacturers now offer a wide variety of 406-MHz devices, with or without GPS, manual or automatic activation, a variety of waterproof housings, etc.

Courtesy Datrex

PLB units are small form factor rescue devices that can be carried in a foul weather gear pocket.

Personal AIS: An automatic tracking system, AIS is used by all types of vessels and vessel-tracking services. It uniquely identifies vessels through an exchange of data via VHF and is primarily used to supplement radar in collision avoidance. The system typically presents the information on a chartplotter or radar screen.

It was inevitable that PLBs and SART devices would begin using AIS technology as a tool in search and rescue. Kannad Marine, a manufacturer of electronic rescue aids in the U.K. is now offering AIS built into a handheld device. Their SafeLink R10 Survivor Recovery System is the first of its kind, a personal AIS device designed to be fitted to a life jacket and assist in man-overboard recovery.

According to Kannad, “The SafeLink R10 SRS is specifically designed as a personal search and rescue locating device. It enables those on board a vessel with an AIS receiver to quickly and efficiently locate and retrieve a missing crewmember. The SafeLink R10 transmits target survivor information, including structured alert messages, GPS position information and a unique serialized identity number back to the onboard plotter. A built-in high precision GPS receiver provides accurate position information to assist in quick recovery of survivors.” In addition to the personal device, Kannad Marine also manufacturers a larger AIS SART device as an alternative to a radar-based SART.

By Ocean Navigator