Hello

Most of the marine traffic at sea uses satellite to pick up the AIS signals. These require a subscription to get the details of that specific ship.

The sites are straight forward to use. I also use. Marine Traffic.com. Some recreational vessels AIS will come up at sea. But their position is often delayed.
 
thataway":lg4rd87v said:
... The sites are straight forward to use. I also use. Marine Traffic.com. Some recreational vessels AIS will come up at sea. But their position is often delayed.

Marinetraffic.com requires an internet connection to use. I have found that in a lot of cases the position reports there can be quite old. I've seen ships plotted, allegedly nearby, but the position report is 3 days old. It is not something to use for real-time collision avoidance. Perhaps having a paid subscription makes it work better.
 
ssobol":3h37b69m said:
thataway":3h37b69m said:
... The sites are straight forward to use. I also use. Marine Traffic.com. Some recreational vessels AIS will come up at sea. But their position is often delayed.

Marinetraffic.com requires an internet connection to use. I have found that in a lot of cases the position reports there can be quite old. I've seen ships plotted, allegedly nearby, but the position report is 3 days old. It is not something to use for real-time collision avoidance. Perhaps having a paid subscription makes it work better.

The Class A signal is picked up on the satellite receivers. There are some class B or B+ transceivers which are also picked up by the satellite receivers.

Did you mean that only boats which tracked by the voluntary stations/AIS receivers along the coasts and waterways would show up? (B+ transceivers are 5 watts vs 2 watts for Class B. The Class B+ also grab time slots and should not be delayed by priority of Class A. If the vessel speed is >23 knots, the B+. will transmit every 5 seconds, vs 30 seconds with Class B.

If I were buying an AIS transceiver currently I would buy a B+ which start in the $625 range to about $780 for a Garmin black box unit. The B are a few hundred less.
 
thataway":3elqn19j said:
...Did you mean that only boats which tracked by the voluntary stations/AIS receivers along the coasts and waterways would show up? (B+ transceivers are 5 watts vs 2 watts for Class B. The Class B+ also grab time slots and should not be delayed by priority of Class A. If the vessel speed is >23 knots, the B+. will transmit every 5 seconds, vs 30 seconds with Class B.

I mean that people who use MarineTraffic.com as their source for AIS info via the web interface can only get the AIS info if they have a live internet connection. While this is not the best way to get AIS info from vessels in your area, I'm sure that there are people who do it because "Hey, it's free."

Of course, most things are worth what you pay for them.
 
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