I own a few Garmin high end units all with base maps the cards I use are the vision card , bluecharts , lakekeview Hd card and a navionics great lakes card and I have not had that problem . I am not sure if the entry level units with installed cards have the same detail that I have with my cards but I sure have not had that sort of problem but my charts are all area specific . The fishing chart and travel charts have completely different details both should be available on the card.