
The Universal Shipborne Automatic Identification System, or AIS, is required of all large commercial vessels in the air and on sea. The system “squawks” out basic information: name, call sign, heading, speed, length and destination. With the exception of military vessels, all other large ships are required to have complex, expensive transmitters that continuously send out this wealth of information to other vessels.
An AIS receiver is a little black box that doesn’t “squawk” but “listens” to the VHF channels that carries the information coming from the larger commercial vessels. This little box is available from an innovative Seattle-based company called Milltech Marine for $189. (Two other, more expensive units are also available, but the cheap one works fine).

The AIS black box and VHF antenna splitter both require a 12 volt power source, which you can wire from your main electrical panel. However two cheap 6 volt batteries joined in series will give you the necessary power while you’re testing the systems, particularly if you’re not comfortable going into the DC panel.
Milltech also tells you which GPS charting programs are compatible. They list about 15, including two that are Mac compatible.
The Milltech webpage is designed for recreational mariners. It gives you step by step info on setting up the system using your PC or Mac laptop. Bottom line: Milltech is a winner: reasonably-priced products, complete tech specs on the web, great customer service, and prompt replies to emailed questions.