Mail me a sample of the data from the raw data window and a screen shot of the instrument connection page in Exp.

It is still probably a problem with your GPS.

DuncanR wrote:

Fredrik, again, this is not an Expedition problem it is certainly a GPS problem.  Try a different GPS, preferably hooked up a different way, and see what happens.
From your tracks above you can do that at a mooring, you will know soon enough if it has worked!

There's no doubt it's a GPS Problem, I've seen it too on old plotters.  
I've cleaned the resulting corrupted log files using smart sorting and filtering techniques then MS Excel commands to fix the GPS outliers (where there's a big jump in Lat or Lon, ignore the error value and replace it with the average of the two either side - works pretty well)
The KND log File Cleaner may also sort out the error data post fact - haven't tried as I don't currently have the problem.  I believe it's freely available.
For a quick fix for use on-water, buy a simple $30 USB puck GPS, stick it on the nav desk with blu tack and use it as an alternative GPS source in the interim while you work out the GPS issue.  Easy to set up in Expedition.  I ran a race boat for about 5 years with this setup until we eventually ditched the old plotter.

Last edited by David (9/04/2018 3:48 pm)