AIS Radio, My New Best Friend

One of the new additions to Tara’s inventory was an AIS radio made by Standard Horizon. AIS is a service that all ships over 100 tons must have on board and it’s a bloody good idea. When used with the Radar it makes life a lot easier at night.

While we only have a receiver (transponders are another $1000 but will be worth it if we’re going to make ocean passages), it is very useful.

The way it works is that the navigation information from a ship (speed, course, heading) is broadcast over the digital VHF channel 70 and updated every second. The computer in the radio then takes our information (speed, course, heading) and plots where the other guys are, and gives you their information and calculates their bearing (where they are from you on the compass), closest point of approach – how close you’ll come to one another; and when that will happen.


So when you’re out at night you can see lights at between 10-12 miles away. We then correlate this with the Radar, and the AIS radio. By using eyeball, Radar and AIS, you can keep all traffic straight as to who is where, and also understand whether you’re on a collision course or not. The toughest thing about navigating at night is figuring out which way a boat is going relative to you. The AIS system gives us the ability to understand that early in the process and do small course corrections to avoid traffic.

Awesome use of technology – right up there with Autopilots, GPS, bow thrusters, powerful anchor windlasses, roller furling, electric winches ….. and rum.