Richard Ray informs us :
I noticed after updating to iOS 5 that all my maps downloaded in iNavX were gone. This happened because the iOS update 5 update requires a full restore of the device and the charts are not stored in the iOS backup (because of iCloud). Let me know if you experience any different operation.
To restore any NOAA charts, Select any NOAA region, then select the Recent filter (looks like a clock), then select "Update Maps".
To restore any charts from X-Traverse (Navionics charts, NV-Verlag, Solteknik, aso.) : Select the folio you want, select "Update Map List", select a map and then "Download all".
If you have any problem with your X-Traverse account, Contact support@x-traverse.com