Lowrance Hook Reveal Series Operator's Manual page 27

You can also get a message if you try to use a restricted feature
when the Navionics chart card is not activated. To activate the card,
contact Navionics.
Navionics specific chart options
Chart overlay, orientation, and look ahead options (previously
described in this section) are common to both C-MAP and
Navionics charts. The following describe Navionics specific chart
options.
Community edits
Toggles on the chart layer including Navionics edits. These are user
information or edits uploaded to Navionics Community by users,
and made available in Navionics charts.
SonarChart
The system supports the Navionics SonarChart feature.
SonarChart displays a bathymetry map showing high resolution
contour detail and standard navigational data.
SonarChart Live
SonarChart Live is a real-time feature where the device creates an
overlay of depth contours based on your own live sonar soundings.
When you select SonarChart Live overlay the menu expands to
display SonarChart Live options.
Transparency
The SonarChart Live overlay is drawn on top of other chart data. The
chart data is completely covered at minimum transparency. Adjust
the transparency to allow the chart details to be seen.
Minimum depth
Adjusts what SonarChart Live rendering treats as the safety depth.
This affects the coloring of the SonarChart Live area. As the vessel
approaches the safety depth, the SonarChart Live area will gradually
change from a simple grey/white to red.