AIS Display with 2 Boats with same MMSI

[SoggyPaws]

I thought ya'll would find this interesting.
We are in Singapore with a jillion ships. I noticed 2 ships with the purple track between them (first screen shot). Then later, one of the two ships started moving. Both have same MMSI 000000000.
Interesting, huh?
BTW, OpenCPN performs well even with all these targets (and I'm sending them off via internet UDP to Marine Traffic)

[Corsair63]

Most of the times one MMSI 000000000, it means that the transceiver has not been properly setup and it's transmitting as per factory defaults.

but should be old one non decent quality, because most of the modern transceivers do no transmit if compulsory fields are correctly filled.

by the way, S-pore straight and anchorages are terrible areas because of traffic and tropical weather too.
I had too many uncomfortable situations in those waters.

[requiem]

Sometimes people just put in dummy numbers as well, e.g. 111111111.

With two vessels and the same number, I'd be curious how the plotter handled it. How well was it able to differentiate them? E.g. treating it as one ship that jumped around, or using some other properties to recognize there were two vessels?

If you're near the US you can check what you're transmitting here (if it's been picked up by a coast station: https://www.navcen.uscg.gov/ais-vess...cation-service

[Hakan]

if ships are not following the AIS standard all strange thing can of course happen. The MMSI number is the identification for a ship. If two or more are using the same number it's seen as the same ship and consequently "jumping" in OCPN or any other nav-system. Two ships can't have the same number if a legal installation.
What you can do in OCPN if you're disturbed is to use MMSI Properties to exclude that MMSI.