Garmin 521 User Manual

Using Sonar

Medium—many strong returns are highlighted in white.
Low—the least-sensitive setting. Only the strongest returns 

are highlighted in white.

Color Scheme—select 

 or 

. This affects the background 

on all sonar screens, but does not change the Temp Log screen.

To adjust advanced sonar settings, press 

 while viewing a 

sonar screen.
Pause Sonar—Stops the scrolling of the sonar screen.

1.  While viewing a sonar screen, press 

 > 

.

2.  Use the 

 to position the pointer over the fish or structure 

you want to mark.

3.  Press 

.

  From the paused screen, press 

 > 

 to 

continue scrolling.

Range—adjust the range of the depth scale on the right side of the 

screen (auto, or to adjust manually, Manual Range).
gain—controls the sensitivity of the sonar receiver (auto, or to 

adjust manually, Manual). To see more detail, increase the gain. If 

the screen is cluttered, decrease the gain.

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◦

frequency—when using a dual frequency transducer, select how 

the frequencies appear on-screen (200kHz, 50kHz, dual,

or auto).

Zoom—zoom in to a section of the full screen. The zoom is off, or 

set to No Zoom by default. Four options are available:

No Zoom—turns zooming off.
auto 2x Zoom—twice the magnification.
auto 4x Zoom—four times the magnification.
Manual Zoom—set the depth range of the magnified area 

manually. Select 

and then use the 

 > 

 to set 

the depth range of the magnified area. Select 

and then use 

the 

 > 

 to increase or decrease the magnification of 

the magnified area.
bottom Lock—locks the zoom window to the bottom. 
Split Zoom—displays the Split Zoom screen (

Noise Reject (available only when gain is set to Manual)—reduces 

on-screen visual clutter (usually from electrical sources) on the 

screen. Select the top slider bar to manually adjust the value of noise 

rejection. Manually adjusting the amount of noise that is rejected 

helps fine-tune the sonar to show the most detail with the least noise.
When frequency is set to dual (and gain is set to Manual), you 

can individually adjust noise rejection for each frequency.

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