Humminbirds read Navionics and Lakemaster map products. The best for you is the one that has the coverage you want with the detail you want. You can view the current Navionics maps on their website's Web App. There are two map layers. One is Nautical Charts ( Navionics data) and the other is Sonar Charts ( map generated from unit user sonar logs). You can download the Lakemaster lake lists from the Humminbird Lakemaster site.
Auto Chart Live is a unit version of Auto Chart and Auto Chart Pro computer software that creates contour mapping from sonar logs. It will generate contours overlayed on the mapping you have in the unit either in the unit's memory up to 8 hours or directly to a Auto Chart Zeroline card. If you use the unit's memory to record the contour mapping, when the memory gets full, you have to transfer the mapping to a Zeroline card to clear the memory and get 8 more hours of contour mapping.
It is real simple to do Auto Chart Live, just turn it on and watch the contours being created on the Chart View. The contour accuracy will be as good as the time you take to pass over all of the bottom of a body of water.
Since it is mapping you have to start the map creation in the Chart View. Just push the Menu button to get the Chart Express menu and select Auto Chart Live. Then turn Record ON. The next few menu items will control how the mapping is viewed.
This is a couple of Auto Chart Live tracks overlayed on a Navionics Sonar Charts map:
With either of your units, you can do sonar log recording to a blank memory card and have that data processed by Auto Chart computer software or by the Navionics Sonar Charts program. Sonar Charts is a FREE service for Navionics Hotmaps Platinum and Navionics+ map products.
Auto Charts is private contour mapping and Sonar Charts is shared contour mapping.