AIS Location Tracking

AIS (Automatic Identification System)

The AIS location tracking system is a great tool. All vessels in excess of 300 gross tons or which are commercial passenger vessels are required to have (and use) a Class A AIS system. This digitally broadcasts information such as MMSI number, speed, and heading. Large ships use ECDIS systems and smaller ones use chart plotters to track this data. It helps plot courses to avoid vessels in busy areas and in bad visibility and is used to prevent collisions.  Class B systems send different data at lower power and less frequently and are meant for smaller vessels which are not required to have AIS but wish to do so. This is the system I’ve got on board, and I consider it to be one of my most important safety systems, if not the most important one.

Usage

I’ve got a transmitter on board (a Raymarine 650) which runs all the time, even at anchor.  My alarm has gone off while I’ve been at sea and warned me of CPA (closest point of approach) of under 5nm with a cargo vessel in 40 minutes time; I couldn’t even see the cargo on the horizon at the time. After 10 minutes or so, I checked the AIS again and saw that the cargo ship had actually changed course to increase our CPA! Nominally I am the “stand on” (right-of-way) vessel as a sailboat, but reality is often quite different. I’m very happy with AIS; not only is it an important safety device, but it is fun to get boat names and speeds when the boats are just a bit too far away to make out the name.

Tracking

There are several sites online which offer free AIS tracking. The broadcast signals are collected from volunteers with receivers who get the terrestrial signals and feed the websites with that data. There are also satellite receivers, but those services are geared towards fleets of commercial vessels and are pricey. Many of the anchorages and areas that I frequent are out of reception range of the volunteers. This means that the free location services all just show “Pleasure Craft. Position received by satellite” rather than the boat name. If I want to be seen and recognized on the internet, I’ll use an app for MarineTraffic. This lets me self-broadcast the AIS information. Which assumes that I’ve got my StarLink turned on and broadcasting.

Below is the current location of Zanshin according to MarineTraffic.Com. If nothing shows on the map, then my AIS is either turned off or temporarily out of range.