Furuno GP-1871F - Bottom discrimination display

6. FISH FINDER
6-3
To show or hide the A-scope display, swipe the bottom of the screen upwards to show
the layered menu, then tap the toggle box at [A-Scope]. Select [ON] to show the A-
Scope, or [OFF] to hide the A-Scope.
A-Scope peak hold
You can show the "normal" A-scope display plus the peak-hold amplitude picture for
the last five seconds in dots. To show the peak hold display, turn on [A-Scope Peak
Hold] in the [Settings] => [Fish Finder] menu.
6.4.3 Bottom discrimination display
The bottom discrimination display analyzes the seabed echo to categorize seabed
hardness in one of four types (rocks, gravel, sand, mud) and shows the results in a
colorful graphic display. A transducer that supports bottom discrimination is required.
See the installation manual for a full list of transducers which can be connected to your
GP-1x71F. CHIRP transducers are NOT compatible with the Bottom Discrimination
feature.
There are two bottom discrimination displays: graphic and probability.
A-scope display
Fish echo
Single frequency display
Strong
reflection
(bottom)
Weak reflection
(small fish or noise)
*: The probability bar indicates
the degree of trust for the
seabed composition estimate.
(Green=Normal; Yellow=Caution;
Background color=Abnormal)
Probability
bar*
Graph example
Mud probability
(Approx. 25%)
Sand probability
(Approx. 25%)
Rock probability
(Approx. 50%)
Graph example
Graphic: The most probable material on the seabed
(mud, sand, gravel, rock) is indicated graphically.
Probability: The most probaility of each seabed
material is indicated in graph form.
Composition legend
Rock
Gravel
Sand
Mud
Composition legend
Rock
Gravel
Sand
Mud