I have the same unit on my Nucanoe. I have not experienced anything like that, I pretty much leave sonar on high chirp. I think C-Map social maps is your only option for creating chart with the sonar log files from Lowrance. I never could get the Navionics+ card self-map to work right, so I'm using C-Map for a lake I fish that Navionics has no data on. I've contributed logs, and it took a few days but I get an email the logs had been processed. I just go to the website and re-download that map whenever it is updated. Its all there is for that particular lake. When I fish the big lakes that have detailed coverage in Navionics, Like Lanier, Allatoona, Oconee, I reinsert the Navionics+ card.