What is AIS?
AIS (Automatic Identification System) is a technology used for collision avoidance, similar to radar. A special transceiver is installed and programmed with a unique ID (MMSI number) obtained from the FCC or other federal agency. Additional details about the ship such as name, type of ship, VHF call sign, and draft can also be programmed into the device. It then uses GPS to calculate the ship’s position, course, speed, and heading, and transmits all of this data digitally across the VHF radio. Ships and other land-based stations within range (about 10-20 miles) can receive that information and display it on their navigation systems.
Advantages of AIS
Received AIS data is typically displayed on a ship’s navigational system. While larger ships use an ECDIS (Electronic Chart Display and Information System), smaller ships will typically use a chartplotter or other AIS-enabled device. On Shantí, we have a Class B AIS transponder, which is active whenever we are motoring or sailing. It allows us to transmit our data to area ships, and also allows us to receive other ship’s data, as well. Each ship is displayed on our chartplotter as a small triangle, which we can click on to get more details. Both our VHF radio and laptop can also receive AIS data and display it on their screens. In addition to radar, AIS is a wonderful safety feature!
Here are a couple pics of what AIS looks like on our chartplotter, and the detail screen we can see:
AIS and the internet
Many land-based stations receive AIS data and feed it to the internet. This allows websites and smartphone apps to display the data in various ways. Some websites have fully interactive maps with icons showing each ship’s location, while others are simply text-based. While we would never rely upon any of these sites for navigation, they are useful for tracking ships and providing information about them. Because we transmit our data, these websites can track us, too.
AIS tracking websites
We have provided what we feel are the two most useful AIS tracking services available: MarineTraffic.com and VesselFinder.com. Both services include interactive maps that will show our position as well as the other navigational data we transmit. They differ in their timing and how long their maps display (persist) the information. The first, MarineTraffic.com, displays information in real-time. If we are in range of a station, you should see us on their map. However, if we go out of range, and there’s no other station in the area, we immediately disappear from their map. The second will display our last known position and persist it on their map for several days (or even weeks). However, their system is delayed by 12 hours, so everything you see is a half day old. Using both together, though, should give a pretty good idea of where we currently are.
On a smartphone?
If you are viewing this page from either an Android or iPhone, there are several apps which are better suited for displaying the maps and other information. We currently use FindShip, which is available for both Android and iPhone, but there are others as well. These websites or smartphone apps may ask for our MMSI number or possibly our VHF radio call sign:
NOTE: There are many places that do not have ground-based AIS stations. If you do not see us, or you know the location they show is not up to date, then we are probably in an area that has no ground-based AIS stations to receive our signal. Also, we have noticed that many places will show SOME ships but not others. We believe this is due to the fact that many vessels carry satellite-based AIS, which these websites and apps might pick up. But, since ours is Class B, it relies upon ground-based receivers to pick us up.
Call sign: WDH4988