After furthur research found out that the newer Navionics chips don't have the old structure, roads, channels etc. Decided to get another SI for use on the trolling motor and will move the 797 next to the 997 by the steering wheel and use the 797 for following the creek channels etc unless someone has a 2008 Navionics for NC they would be willing to part with. Next question will the 997 let me access an earlier version of Navionics if I use a chip?