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Hi all,

Not directly a Raymarine question but very relevant. I understand the difference between a Class A and Class B but i'm still unsure about journey details.

There seems to be no way of setting origin or destination with a class b transeiver ( particularly the AIS700 or AIS650), this feature is only available on a class A. However, when looking at online tracking websites ( Vessel finder, Marine traffic) journey details appear for some vessels that are definitely equipped with class b systems rather class A.

Question is: do these websites just automatically establish journey details from track and heading or are they entered some other way?

Many thanks,

Rom
Hello Rom,

I don't know where those sites source their information from, but the Class B AIS standard has no support for 'Voyage related data' as Class A does in its Message 5 (see https://www.itu.int/rec/R-REC-M.1371-5-201402-I/en for details and [url=https://en.wikipedia.org/wiki/Automatic_identification_system[/url] for a more-readable explanation.)

Many larger private vessels do in fact fit Class A - are you sure that the vessels in question aren't doing so?

Regards,
Tom
It appears that these Internet based apps build a database of various points from where AIS data is received. I have noticed that the Ferries on Long Island Sound will show multiple runs between two points as the ferry traverses it’s daily schedule.

I would expect that what you are seeing for class B AIS systems for not AIS defined start/destination data, but historical data based on where the vessel has been.

Just an observation.
I’ve used a smartphone app called OnCourse to report my position and destination to MarineTraffic. I do not have AIS onboard.
Hi Tom,

Thanks for the information. I believe i got my answer from Marine Traffic.

The reason the vessel name and other class b information wasn't available was because the information was being received via a satellite as no shore receiver was in the vicinity. Voyage data is determined from vessel location, so for a class B, if the vessel is underway you will see the origin but not the destination. If the vessel is stopped you will see it's last voyage. Class A will show origin and destination as you indicated.

That's for marine traffic, I am not sure how it works with other sites.

Thanks again,

Rom
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