I just received a SR162 dual-channel AIS receiver, which I will be using on
my sailboat -- the old single-channel SR161 will end up at home. I've been
testing at my house it these last couple of days, and have been amazed at
the range I have been getting. I've seen many ships 100 to 200 nautical
miles from my position, and last night saw one at 492 miles, and another at
673 miles" (this one was "Ikarugu", a freighter heading to Long Beach, CA)

Of course, I also moved my whip antenna from the deck railing to the roof,
which has to help a tiny bit. I am at about 1000ft elevation, 4 miles from
the coast, and 40 miles north of the Golden Gate Bridge. Still, this is so
far beyond line-of-sight that it has to be tropospheric ducting.
Occasionally, VHF signals make the trip from Hawaii to California (about
2000 miles), and an interesting by-product of widescale AIS deployment is
that there are now all these AIS "beacons" spread out all over the oceans,
running continuously.

AIS DXing - who holds the record?

-Paul