Check out this video : https://www.youtube.com/watch?v=uJCjNZQWx9s .... it shows you how to select between the base map (preloaded map) and the sd card maps. You don't really "load" the map info off the card into the unit ... you just have to tell the unit which "map" you want to see/use.

I still don't have a sd map card for my unit, and just use the preloaded outline maps. Some lakes do have contours marked in 7ft - 17ft - 27ft contours, but not the larger lakes in the state.

Hope that helps !!

... cp