What does it mean when a Garmin Chartplotter goes into overzoom mode?

Most Garmin chartplotters have the ability to add optional navigation charts or come with preloaded navigation charts. The charts are a digitized version of existing government and other official charts.

The term overzoom means the map is zoomed in on an area to the point that you are no longer getting optimal presentation of the mapping detail.

BlueChart contained multiple charts with different scales. One region of BlueChart could have several dozen charts of different scales. Because of these different scales, some areas will go into overzoom at 2 miles, while others will not be in overzoom until 120 feet. Older Garmin devices will show "Overzoom" on the chart when zoomed closer than the scale allows.

BlueChart g2 and g2 Vision take multiple charts and combine them into a single chart with a single scale. This change allows BlueChart g2 and g2 Vision to be scaled down to 200 feet without overzoom while in covered areas. When zoom is set to a scale smaller than 200 feet, the chartplotter will be in overzoom mode, though no indication will be made on the screen.

To leave overzoom mode on your chartplotter, simply use the zoom out option on the chart screen until the map returns to the optimal mapping detail.

"WARNING: Digital charts are intended to be used as an aid to traditional navigational charts, not as a replacement. Please read the full disclaimer here before purchasing or using Garmin charting."