Garmin gpsmap 521 User Manual

Using Sonar

When connected to a transducer, the following chartplotters can be 

used as fishfinders: 
GPSMAP 420s  GPSMAP 450s 

GPSMAP 421s  GPSMAP 451s 

GPSMAP 520s  GPSMAP 525s 

GPSMAP 521s  GPSMAP 526s 

GPSMAP 550s  GPSMAP 555s 

GPSMAP 551s  GPSMAP 556s

Select the Full Screen option to view a full-screen graph of the 

transducer’s sonar readings. 

  From the Home screen, select 

 > 

.

Use the Split Frequency screen (dual-frequency transducer only) to 

view both the 50 kHz and 200 kHz frequencies on the same screen. 

A 50 kHz frequency graph appears on the left; a 200 kHz frequency 

graph appears on the right.

  From the Home screen, select 

 > 

.