Create Bottom Structure Mapping from Sidescan Mosaics in GME
Mosaic 1
Simply add the mosaic image into the chart using "File - add - now choose either an ecw, a jp2 or a map (ozi) format image. Its best to remove the background water for doing this, and add it in later, alternatively you can open 2  instances of GPSMapedit and work in one - copying your work directly across to the other as you progress. Simply copy in one window, and paste in the other. It works seamlesslessly.
Mosaic 2
 You can zoom in and select areas you want to mark. In this case I am going to mark the edge of the soft mud
Mosaic 3
Now select the create object - polyline  - tool, and draw your polyline. Right click at the end of each line and select "Navico Bottom Structure"
Mosaic 4
When your editing is complete simply export to shapefile. The line will appear in your Lowrance chart, and can be activated / deactivated by using the "fishing Ground" category. This also activates bottom structure areas - see next page.
Mosaic 5
A Bottom Structure area - an Information Point could be put nearby.