Tracking problem OpenCPN 5.8.2

[YotMax]

Hi, hoping someone can help with an issue I'm having.


Our vessels are AIS equipped and we routinely plot their positions at our base using OpenCPN. Recently the question arose that we may want to provide our vessel tracks for any subsequent review. No problem, right? I just go to Options>Ships>MMSI Properties>New>Track Mode enter our vessel MMSI and mark it "Always, Persistent".


Except that this doesn't always work. It's quite annoying. The first time the vessel turns on its AIS, OpenCPN will track it as required and record that track in the Route & Mark Manager>Tracks tab.



The vessel eventually returns to base and shuts down. Some time later (could be same day, could be several days later) it powers up again and transmits AIS data. OpenCPN will plot its position and even show a track. But there's no record of the track kept in the Route & Mark Manager. Or at least not consistently - it does sometimes record it but I've no idea why sometimes it does and sometimes it doesn't.



I now have 3 separate computers running this with slightly different configs and they all seem to have this problem:


1 x Windows 10, 2 x Windows 11
1 x serial AIS input direct from the AIS receiver, 2 x network TCP/UDP input
2 x have Options>AIS Targets>Lost Targets both options ticked, 1 x does not have options ticked

All running OpenCPN 5.8.2



I know there are other means I can get this info (eg MarineTraffic.com, AIS filters, etc) but we really want to be able to extract a gpx file and we are already set up with OpenCPN which does everything we're wanting. When it works.


Anyone?

[YotMax]

OK, I've made progress through trial and error and come to understand these options much better to the extent that it now does what we need. For the benefit of anyone wanting to do something similar here's the story.

Turns out that there are several settings at play in this scenario and how they interact can be quite subtle and even unexpected.

The settings are:

o AIS>Show AIS Target Tracks [aka AISTracks]
o Options>Ships>AIS Targets>Lost Targets (both settings) [aka LostTargets]
o Options>Ships>MMSI Properties>New>Tracking [aka Tracking]
o Options>Ships>AIS Targets>Show targets tracks length (min) [aka Tracklength]


Also Options>MMSI Properties>New>Tracking>Persistent is always required to be checked.

So I add an MMSI into the MMSI Properties table. If Tracking is set to "Always" then it will be tracked when the vessel begins to broadcast AIS data. Trouble is, if LostTargets values are checked then once the vessel stops broadcasting, it will eventually be marked as "lost" and deleted. The track stays but the vessel seems to remain "lost" even if it recommences broadcasting and it doesn't get tracked until OpenCPN is restarted. If instead LostTargets are not checked, the vessel is always tracked as one single very long track from whenever the vessel starts broadcasting to whenever OpenCPN is shut down. Recording recommences once OpenCPN is restarted and the vessel starts broadcasting.

What I ended up with was Tracking set to "Default tracking". That required AISTracks to be checked and meant that all AIS targets are tracked. Tracklength was set to a reasonable value so as to avoid too much screen clutter. I found 10-20 minutes was OK. Most importantly, LostTargets were both checked and set to reasonable values (for us that's 20 and 30 mins). So when the vessel hasn't transmitted for 30 mins it is marked "lost" and removed from the AIS target list. The track however remains indefinitely, unlike most targets whose track is removed once they are lost. Once our vessel starts broadcasting again then a new track is recorded in the Route & Mark Manager.

So there we have it. Our selected vessels (only) are tracked every time they go out. Should we ever have need to provide evidence of our vessel track or location then we can get that. This can be essential for us given our vessels perform search and rescue operations.

[YotMax]

Spoke too soon... this morning our vessel powered up and went out. OpenCPN recorded nothing. It was tracking the vessel as an AIS target but no recorded track in Route & Mark Manager. There were no settings changed, about all that was done was to clean up some of the earlier tracks from the testing.

I should've known something would break as soon as I posted! Seems more testing is needed.

[Hakan]

I made some tests and can reproduce your report.
I've a mmsi properties rule for the ship "Polstjernan" that has survived a couple of Win/OCPN restarts. The rule is "Always track" and "Persistent". See screen shot.
To test your reported scenario as I understand it:
While O is running I stopped data update and when "Polstjernan" disappeared due to time out I restarted data update. And no new track was started after that. Also it not continued a present track.

So, for a ship with a persistent track and the ship symbol is lost due to time out the persistent track is not restarted when the ship appears again. I'd call it a minor bug and will file an issue.


See https://github.com/OpenCPN/OpenCPN/issues/3330

[YotMax]

Yes I can confirm that is the issue I found. Thank you for checking and for the confirmation Hakan. Also thank you for raising a problem report. Or if you prefer and could point me in the general direction, I'm happy to raise a problem report if that is appropriate.

As per my last post, I think may have stumbled across another bug in this general area but I am still trying to get a handle on how or why it appears.

[Hakan]

YotMax..
The issue mentioned above is corrected in Github master to be included in next OCPN release.
If you want to try you can test a alpha version here but beware it's a version from ongoing development and not beta tested so maybe not for navigation.

[YotMax]

I've installed the beta test on one of our computers (not used for navigation!) and will check it out over coming days. Thanks again.

[YotMax]

Thanks for your help Hakan. I've tested run the alpha fix over numerous days and variations and can confirm it rectifies our problem. I now have a suggested enhancement but I'll raise that separately.

[Hakan]

Very good. Thanks for your confirmation.