Furuno FEA-2107 Operator's Manual page 239

Areas
To include areas in the chart alarm, check the Danger Area box in the Area page of the Plan User Chart dialog box.
Danger Area must checked, otherwise danger areas of a user chart cannot not be used in the chart alarm. The
dangerous area is drawn in red instead of dark yellow (color may be different depending on Palette in use).
In the Area page, you can
include areas in the chart
alarm by checking Danger
Area.
The figure below shows the behaviour of a dangerous symbol, line and area in the chart alarm check.
Presentation of
Dangerous Area
Presentation of
Dangerous Symbol
Presentation of
Dangerous Line
11. Chart Alarms
11-7