Originally Posted by twistedtree
I always assumed the different sites were all using the same underlying data. I'm not sure if I read that somewhere or just assumed it out of thin air.
Originally Posted by cappy208
@Capttom: The websites don't work like that. You enter your. Desired vessels name, If it's in range is shows up. If not it doesn't.
Twisted, I can confirm that they don't all use the same data, since when I turn on my AIS, even if I leave it on for hours, I show up on some sites, but not others. Looking more closely, other large commercial boats in the same area also show up on the same sites as me, but not on the ones I don't show up on. Moral of the story: not all sites have receivers near my marina.
Cappy, I tend to use the sites the opposite way; select an area of interest and see what ships are there. Some harbors show no ships on one web site, but a bunch of them on another. So again, I know the coverage is not consistent from site to site.
What I'd really like is some way to know which sites cover a given area of interest, like where I am right now (for the people ashore) or where I'm going (for me.)
As I said, one of the sites does allow you to display receiving stations, but I can't find that option on the others. The ideal would be a "coverage map" like you see for cell phone companies. But there's no competitive advantage for AIS web site companies to do that, so it would have to be a 3rd party.