We now seem to be through he major shipping lanes off the Brazilian coast, and the last several days have made us very thankful for AIS.
AIS (Automatic Identification System) is a protocol that allows ships to communicate with one another via transmitting and receiving beacons. Each boat that has an AIS transceiver broadcasts its own name, vessel size and type, course, speed and other details. In return the beacon also receives the same information from other AIS-equipped vessels in the vicinity.
The system works on the same frequencies as VHF radio, and the range is about the same – more or less 20 miles for a boat like ours with the antenna at the top of our mast. So, this system allows us to “see” other vessels long before they appear over the horizon, and it alerts other vessels to our presence.
In theory, sailing vessels on the open ocean have right-of-way over power craft like freighters and tankers. In practice, though, it takes someone braver than us to assert a right-of-way principle when a 1000’ (300m) long ship is on a collision course with our 43’ (13m) sailboat. And while the requirement is that all ships maintain a watch at all times, our experience has been that that rule may not always be followed.
So, we use our AIS system to take early action to avoid other vessels, and we’re happy to have it.
All’s well onboard.
Day Nineteen
154nm
18 36.8S 36 13.9W
