Before explaining what an AIS SART is, it is necessary to understand what AIS is. AIS (Automatic Identification System) is a means by which vessels can ‘see’ each other on radar screens and plotters. An AIS-equipped vessel is able to see all the other vessels around it which are transmitting AIS data. Some small boat AIS products are receiver-only, enabling the boat to see other craft, but not to be visible themselves to those other vessels. All ships over 300 tonnes are required to have AIS transponders (transmit and receive). AIS can the position of vessels on compatible radar displays, chart plotters or PCs. As well as showing a vessel’s position, speed, course, vessel name and MMSI number are also transmitted.

An AIS SART (Search and Rescue Transmitter) is an emergency beacon for use on a life raft. It transmits a signal which is received by all AIS-equipped vessels within range, enabling any of those vessels to home in and offer assistance. The alert message contains GPS position, course and speed, ships name and a unique ID. AIS SARTs which meet the IMO SOLAS specification can be used as an alternative to Radar SARTs. Vessels over 300 tonnes must either carry Radar SARTs or AIS SARTs.

Whereas an EPIRB or PLB is a 21st Century alternative to rocket flare, to raise a distress alarm, an AIS SART (or Radar SART) is a 21st Century alternative to a hand-held flare, to pinpoint your position. The difference being that it has much greater range, being limited only by line of sight between the rescuing ship’s VHF antenna and the life raft where the AIS SART has been activated.