Problems with intermittent bad GPS data

[tkurki]

My bet was for a device malfunction but now it seems an OpenCPN beta issue.

My money would be still on device malfunction - the issue not appearing after a new beta does not mean that there were a bug, if it is an intermittent problem with the gps.

If you really want to troubleshoot something like this you need to look at the data moving in the system, from where it is coming from to where the error appears, to try to reproduce the issue,