what is the purpose of hooking up gps to this unit if you cant store waypoints to it. and will a gr 16 gps module work with this unit.
The 47 and other Matrix trackplotters are very capable, even without charting.
You can record and plot waypoints, tracks, and routes. This makes it easy to return to productive areas. Using HumminbirdPC to export these features in GPX format makes them available for analysis in a number of database, spreadsheet, or geospatial applications. This analysis can help develop strategys for future fishing.