AIS does this by continuously transmitting a vessels identity, position, speed and course along with other relevant information to all other AIS equipped vessels within range. Combined with a shore station, this system also offers port authorities and maritime safety bodies the ability to manage maritime traffic and reduce the hazards of marine navigation.

Due to the great safety benefits offered by AIS, this technology was made compulsory throughout the world in 2002 for all passenger ferries and vessels over 300 gross tonnes.

How AIS works

The Automatic Identification System was developed to allow ships and coastal stations to accurately locate and identify one another. An AIS transceiver uses VHF radio and GPS technology to communicate with other nearby ships.

An AIS transponder determines its own position, speed and course using a built in GPS receiver. This information is combined with other important navigation information and automatically communicated between AIS equipped vessels without any user interaction.

AIS transponders on other vessels and coast stations receive this information and use it to build up a live graphical display of traffic in the area. The transponder can be connected to many types of chart plotter or PC charting software to give a RADAR type display of vessel positions. AIS does not require a radar, but can offer similar capabilities and even enhance a radar image if a radar has already been fitted to the vessel.

The range or coverage of the system is similar to a VHF radios. The system also has the advantage that VHF radio signals will travel around bends and over islands giving better coverage than RADAR or enhancing a RADAR picture when used together.