I have a Furuno Navnet VX2 with a C-Map SD card (West Coast). The chart will sometimes display of mix of chart color/detail with white sections showing nothing. The boat icon will even transition from the color/detail section of the chart to the white section. I called the local Furuno dealer who said the chart software has varying levels of detail depending on location and zoom level. Is that right? Wouldn't chart data be displayed up and down zoom levels for the same location?