AIS is the shortcut for Automatic Identification System. Since  01.01.2005 all SOLAS-Ships above 300 tons and all passenger vessels have to be equipped withAIS. All ships equipped with AIS permanently broadcast via two dedicated VHF channels (CH 87 B and 88B) information about their MMSI-number, callsign, name, position, course, heading, speed, rate of turn and type of vessel. 

AIS enables all participants (ships and VTS stations) to receive information about trafic in there vincinity and to use these data for their own purpose, esp. for collision avoidance.

So  you no longer have to guess whether that High Speed Ferry that just appeared over the horizon might be dangerous for you as Yacht - AIS automatically calculates the CPA (Closest Point of Approach) and TCPA (Time to Closest Point of Approach) for you. And if in doubt, you know its name and call-sign and you can easily give the vessel a call on VHF or even make a DSC-call.

But the AIS-system is not a replacement for conventional radar but rather an amendment. AIS can only display targets transmitting AIS-data, but not other objects dangerous to save navigation like land, floating objects, fishermen, yachts any navy ships. 

Participating in the AIS-system is of great interested for pleasure boats. Up to now displaying AIS-data was only possible twith expensice vector-chart-systems. Now Yacht-AIS enables you to display AIS-data on your normal laptop in conformity with IMO and IALA recommendations. All you need is the Yacht - AIS software and a small AIS receiver.

By the way, if you want to get an insight how many ships are already equipped with AIS, take a look at  www.aislive.com (registering is free and easy; we don't have to do anything with that company). All these information you miss onboard without Yacht-AIS.