Range for AIS 600/800 ?

[baz]

Subject: Range for AIS 600/800 ?

If you have an operating AIS 600/800 what is the typical range for other boats seeing you displayed on the Chart plotter ? I've had one experience of a boat with AIS 600 and was able to track the boat when it was at around 1 mile from me and this was with a clear line of sight with the boat slowly disappearing in front of me.

Is AIS 600/800 restricted to line of sight ?

My research brought this info up.... https://www.westmarine.com/WestAdvisor/Be-Safe-and-Be-Seen-with-AIS

The system’s range is similar to that of your VHF radio, essentially depending on the height of the antenna. Its propagation is slightly better than that of radar, due to the longer wavelength, so it’s possible to “see” around bends in rivers or over islands if the landmasses are not too high. AIS information is not degraded by rain-clutter like radar, so it works the same in all weather. The consensus among safety experts is that AIS is extremely valuable, especially if you travel at night or in crowded shipping lanes with restricted visibility.

 

[ixlr8]

Unlike radar, AIS is not line of sight. AIS value is limited to how many of the other boats around you are equipped with a transmitting AIS. I would say that at least 90% of the vessels in the waters I normally travel do NOT have a transmitting AIS, thus limiting its effectiveness.

 

[fishheadbarandgrill]

AIS operates within the VHF band. Therefore it is Line Of Sight. That doesn't mean that you can't get ducting of your transmission and reception. Height of the antenna will also make a difference as well as power.

 

[Chimo]

I also find that ais positioning sometimes has a lag. I can see a vessel and have it on radar but the ais signal has the vessel plotted behind where it actually is located. That being said I find it very useful for seeing freighter/tanker traffic “around corners” in situations where the radar may be blocked by an island.