EPIRB stands for Emergency Position Indicating Radio Beacon. An EPIRB is activated when a ship sinks. The water pressure releases the EPIRB from the ship and is activated by the contact with the water.
Then, the EPIRB will send an emergency signal via the satellite system, with the so-called G-EPIRB a GPS location will also be sent. An emergency signal will also be sent via the international emergency frequency so that you can be found by SAR ships, helicopters and airplanes.
As you have just been able to read, the emergency signal from the EPIRB is automatically released. Suppose your ship decays and you are in a life raft. The chance of findability is considerably increased with the SART. The SART must be placed as high as possible in the life raft to let the signal reach as far as possible.
In addition to the SART, there is also the AIS SART. The difference between these two lies mainly in the fact that the AIS SART has built-in GPS, this AIS SART transmits a signal on the AIS-VHF channels every minute. There is also a difference in rescue indication, with the ‘normal’ SART, there will be an indication of incoming help on the SART. This is not the case with the AIS SART.