I was pretty unhappy when my 12-year-old Raymarine depth
instrument failed but after researching options I ordered a Garmin fish
finder/chartplotter combination that has a feature I'm excited about. I won't know more until the unit arrives and I get it installed.
It's called Quickdraw Contours Mapping. You turn on the recording feature, drive your boat
around and it produces a bottom map with 1' contour lines. The chartplotter
saves those maps on a MicroSD card and they can be uploaded to a Garmin
Website for sharing (https://connect.garmin.com/start/quickdraw/
As you would expect from Garmin, there's not a word about the format of those files.
Has anyone looked at them with an eye to incorporating them with OpenCPN
? There are many small basins which are not well charted. Running one's own survey
of those areas would yield an excellent supplement to the NOAA charts
which include those basins.