A stand-alone AIS transceiver is a must for both coastal and offshore sailing craft, especially around large harbors with lots of ship traffic and sometimes dense fog. AIS-equipped VHF radios are generally limited to receiving AIS transmissions and displaying them either on a small screen or a separate chartplotter.  To alert another vessel, the operator can either call by VHF radio or activate the DSC (digital select calling) function, which transmits the vessel’s name and position with the vessel’s Maritime Mobile Service Identities code. The advantage of a self-contained AIS transceiver is obvious: Every AIS-equipped vessel in your area is…