Holger wrote in news:Holger.1zo5c7
@news.boatbanter.com:

Well, at least in the Malacca Straits some buoys are equipped with AIS
transmitters sending information on their type, position, light status
and weather information.
On the Great Lakes meteorological and hydrological data is broadcasted
every 15 mins.



None of the bouys have AIS transmitters on them. There is a shore
station with a tall antenna in the area that transmits all the data for
all the stationary objects every, I think the specs say, 10 minutes, so
as not to jam up the time as the objects aren't moving, anyways. This
shore station may have a range of over 50 miles from its lofty antenna on
some communications tower. What you're hearing is the bouys' data sets
from it, not the bouys, themselves. Your VHF AIS system isn't a radar
looking for RF from an object. It's simply displaying data sent from
anywhere about the object at that location.

If someone reported a container had fallen off a containership at X
location and the end of it was sticking out of the mud, the guys running
the AIS fixed stuff transmitter (it doesn't listen, it's just a
transmitter) simply add the data on this container at X location to the
computer that stores and runs the transmitter, the container instantly
showing up on everyone's AIS display blinking away in some sort of new
warning mode I haven't seen, yet.

Instant, graphical, constantly updated and displayed notice to mariners
is one of the finest things AIS can do if the bureaucrats tasked with the
notice to mariners will cooperate and not treat AIS like they're being
forced to do slave labor in its upkeep. It replaces those way-too-late-
for-anything stupid paper reports of old in a very beneficial way.