Boyd, you say "that tutorial says they may be available as geoTIFF. If possible, that is what you will want. If not, that tutorial mentions a program that can convert to geoTIFF.
Once you have the geoTIFF you should be able to use a couple different programs to convert to Garmin's "custom map" (.kmz file) format. Have at look at g-raster "
So with my Montana, get the raster chart in TIFF, and convert it to .kmz with g-raster
That is my mission?
Thanks.
-Bill