I have the Lowrance LMS-522-IGPS and I love the unit, but I have a friend who has the eagle version listed above and it seems to be almost identical to mine with a small exception.I am not able to see the river channel darker color on his that I can on mine.Am I missing something, or does he need to buy a chip map of the local lake and install on it or what? Any help is appreciated.Would like to be able to follow the river channel by site on the gps is what I want to accomplish.I am talking about on the eagle unit now, not the Lowrance. Thanks for any help.