An Automatic Identification System (AIS)  is an electronic device that allows you to see other vessels (who also have AIS) on a chartplotter.  Ships and ferries are required to have AIS, and it’s becoming more common for smaller vessels.  AIS for smaller vessels comes in two types–receive only that allows you to see others, and transmit/receive that allows you to see other and for them to see you.  AIS uses a combination of GPS and VHF to transmit and receive information.  A chartplotter will display a triangular mark for each vessel it is receiving a signal from.  Selecting a mark then brings up a screen showing information such as vessel name, home port, vessel speed and for ships, it shows what cargo it’s carrying.

The main reasons for having AIS aboard is for safety.  It’s kinda like an modern form of radar since it allows you to see other vessels electronically.  Radar of course also allows you to see land and rain squalls.   We’ve been in thick fog where we relied on our radar  to locate ships that were blasting foghorns.  Having a more accurate system at the helm will add redundancy and safety.  Also, on ocean passages the AIS can be used as a warning to sound an alarm when a vessel broadcasting AIS gets within a certain distance.

I decided on a class B AIS from West Marine that transmits and receives information.  It has a “silent” button on the case that allows you to silence the transmit function.  The installation involved lots of wiring–coaxial wire to a VHF antenna (fortunately my boat had a spare VHF antenna installed on the main mast with the wire coiled and labeled in the bilge–shows somebody was thinking ahead!), a cable to a GPS antenna (not sure where I will mount this antenna yet), PWR/GND wires to the electrical panel, and 2 strands on NMEA cable to the chartplotter.  I decided to tie the AIS into the Garmin chartplotter at the helm.  When I installed the cable for this chartplotter, I ran the data cables near the electrical panel so they will be easy to get to.