AIS vessels on a B&G chartplotter
Some key data:
Vessel name: The vessel’s name is transmitted – some AIS transmitters may take a while to send this, but you will always have the MMSI (see below) should you wish to call a vessel.
MMSI: This is a unique identifier that is programmed into the AIS transmitter and the DSC radio, issued by a national authority (Ofcom in the UK).
Call Sign: The vessel’s unique callsign is assigned by the national authority and allows you to identify the ship or craft and call them if necessary.
SOG: Speed over ground.
COG: Course over ground.
CPA: Closest Point of Approach. This is the closest that you will come to the vessel in question should you both maintain your current course and speed.
TCPA: Time to Closest Point of Approach. This states when the closest pass will occur.