Garmin gpsmap 4008 User Manual

Using Sonar

When connected to an optional Garmin GSD 22 sounder module and a transducer, your chartplotter 

can be used as a fishfinder. The GSD 22 connects through the Garmin Marine Network and shares 

sonar data with every chartplotter connected to the network.

Select the 

 option to view a full-screen graph of the sonar readings from the transducer. 

The range scale along the right side of the screen shows the depth of detected objects as the screen 

scrolls from the right to the left.

From the Home screen, select 

 > 

.

Use the Split Zoom screen to view the full sonar data from the graph and a zoomed-in portion on the 

same screen.

From the Home screen, select 

 > 

.