Garmin Sonar Settings Explained

Controls the sensitivity of the transducer affecting its ability to see smaller targets.

• High gain is best in clear water

• Lower the gain to clear the clutter

• If unable to see fish arches or other detail

• Cluttered image

• Picture distortion

The traditional transducer mounted to the boat sends sound waves down into the water in a cone shape. These sound waves reflect off objects they hit (fish, seaweed, bottom structure). The soundwave is received back and transmitted to the sounder that outputs an image on the sonar page.  Traditional frequencies are 50 kHz, 77 kHz, 80 kHz, and 200 kHz. Traditional beams are cone shaped and are either wide or narrow beam widths. 

• Narrow beam widths penetrate deeper and provide crisp detail of what is under the boat

• The wide beam widths gives a wider cone expanding beyond the sides of the boat when in shallow water

• Single Frequency: With a single frequency transducer, it is not selectable as there is only a single frequency

• Dual Beam: Works best in shallow water or freshwater purposes

• Dual Frequency: Is best for deep water fishing (offshore) Dual Frequency alternates between 50 kHz and 200 kHz

Chirp frequencies send a continuous sweep of frequencies within a range from low to high. Chirp technology allows for a clearer, high resolution image with greater target separation and crisper fish arches.  

High Band Chirp: Frequencies from 145-230kHz

1. Better target separation on bait and schooling fish

2. Best for shallow water fishing (under 800 feet)

3. High band frequencies deliver a narrow beamwidth that assists in pinpointing fish that hold tight to structures

High-Wide Chirp: Frequencies 150-240kHz

1. Perfect for freshwater anglers

2. The beam angle covers more area in the water

3. High-Wide beam draws bigger fish arches than the standard high chirp transducer

Medium Band Chirp: Frequencies from 85-165kHz

1. Mid-Band Chirp is excellent at targeting Tuna, Marlin, and other billfish

2. Best range for most anglers with a good range between both the lower bands and higher bands

Low Band Chirp: Frequencies from 40-60kHz

1. Best for deep water fishing

2. Helps find the thermocline

3. The stronger the transmit wattage the deeper this transducer reaches. It's important to note that image quality is sacrificed for lower depth readings    

Manage Frequencies: Allows addition or removal of discrete frequencies from the standard frequency menu when using a CHIRP-enabled sounder and transducer

Allows the user to adjust the level displayed on the sonar page. Zoom turned on shows a green mark, and the arrow to the right opens additional settings.

•   Auto: Automatically adjusts based on pre-set depth number

•   Manual: Sets the depth range of the magnified area manually

•   Magnify: Enlarges a portion of the screen

•   Bottom Lock: Sets the sonar data from the bottom depth

Adjusts the range of depth scale for traditional and ClearVü™  scanning sonar views. Under SideVü™ scanning sonar menu the range adjusts the width scale.  

•  Auto: option that will change the range keeping the bottom within the lower portion of the display

•  Manual: option enables the user to view a specified range

Transmit: turns on or off the transducer when not needed.

Sonar Setup Sonar settings are found from a Sonar view. Select Menu > Sonar Setup. Not all sonar settings are applicable to all GPSMAP® chartplotters and ECHOMAP™ combo units. Refer to the owner's manual for menu options.  

Scroll Speed: Allows users to adjust how fast the sonar loop scrolls.  

Ultra Scroll: On legacy series devices controls the rate of the scrolling speed on display. Ultra Scroll settings from "Pause" to "100%".

Pic. Advance: Adjusts the sonar picture to advance faster by drawing more than one column of data on the screen for each column of sounder data received.

• Especially helpful when using the sounder in deep water, as the sonar signal takes longer to travel to the water bottom and back to the transducer

• The 1/1 setting draws one column of information on the screen per sounder return. Options are 1/1; 2/1; 4/1; 8/1

Interference: Adjusts the sensitivity to reduce the effects of nearby sources of noise.

Color Limit: Adjusts the intensity of colors and highlight areas of interest on the sonar screen.

• Works best after changing the level of detail shown on the screen using the gain or brightness settings

• Increase the color gain to highlight smaller fish targets or create a higher intensity display

• Adjusting the color gain causes a loss in the differentiation of the high-intensity returns at the bottom. To reduce the intensity of the return, lower the Gain

Smoothing: Removes noise that is not part of a standard sonar return, and adjusts the appearance of returns such as the bottom.

• Use Smoothing and Interference together to filter out low-level noise on the image

Surface Noise: Hides noise close to the surface. Wider beamwidths can show more targets but can generate more surface noise.

TVG: Adjusts the appearance of returns to compensate for weak sonar signals in deeper water, and reduces the appearance of noise near the surface.

• Increase the setting and the colors associated with low-level noise and fish targets appear more consistent through various water depths

• TVG allows for the display of targets near the surface that are otherwise hidden or masked by surface noise. This is used when surface noise is very cluttered

Color Scheme: Changes the color scheme. There are many color options. Below are two examples of color options available. Color schemes are user preference.

Color Gain: Adjusts the intensity of the color 

A-Scope: A vertical flasher which displays along the right side of the screen showing what is under the transducer right now.

• A-Scope helps to identify target returns when boat is moving at higher speeds

• Useful for detecting fish that cling to the bottom

A-Scope set to Variable - Peak hold set to Off will display straight lines	A-Scope set to Variable - Peak hold set to 5 seconds

Depth Line: Shows a quick-reference depth line.

Edge or Whiteline: This highlights the strongest signal from the bottom to help identify its hardness or softness. The strongest signal from the bottom appears as a high contrast color. A hard bottom displays a thicker layer while a softer bottom displays a thinner layer. The Edge or white line assists in determining the bottom surface for anchoring purposes.

• Also used for seeking out a specific species of fish by the bottom type they inhabit

Fish Symbols: (Not available on all models) Allows users to set how targets are displayed.

Echo Stretch: Echo Stretch makes targets more pronounced and easier to see on the screen. Set too high, targets will blend together; set to low targets become to small and more difficult to see. 

• Echo Stretch and filter width together to obtain a preferable resolution and noise reduction. Set the Echo Stretch and filter width to low, the display will have the highest resolution, but most susceptible to noise

• Set Echo Stretch to high and filter width set at low, the screen resolution will be lower but have wider targets

• Set both Echo Stretch and filter width to high, screen resolution will be lowest but least susceptible to noise

Figure #1 - shows the Echo Stretch value too high, targets blend together. Figure #2 - shows the Echo Stretch value too low, target are small and difficult to see.

Overlay Data: Customizes the data displayed on the sonar page. Examples:  Depth, Water Temp., Unit Voltage, Speed, Time of Day.

Shallow Water - An alarm sounds when depth is less than the specified value.

Deep Water - An alarm sounds when depth is greater than the specified value.

FrontVu™ Alarm - An alarm sounds when the depth in front of the boat is less than the specified value.

Water Temp. - An alarm sounds when the water temperature is below or above a specified value.

Contour - An alarm sounds when a target suspended within the specified depth from the surface to the bottom.

Fish - An alarm sounds when a fish suspended within the specified depth. There are three size options to choose from All, Medium to Large, and Large.

Shift -  Sets the depth range on which the sonar focuses. It allows the user to zoom in a higher resolution in the focused area.

Btm. Srch. Limit - Limits the search for the bottom to the depth selected when the Range setting is Auto. Bottom Search Limit minimizes the time it takes to find the bottom but does not search beyond the specified depth number.

Transmit Rate - Sets the length of time between sonar pings. Option available only on the traditional sonar view.

Transmit Power - Reduces transducer ringing near the surface. Option available only on the traditional sonar view.

Filter Width - Defines the edges of the target. A shorter filter gives clearly defined edges but allows more noise. A longer filter softens target edges and reduces noise. Option available only on the traditional sonar view.

Restore Sonar Defaults - Restores the sonar settings to the factory default values.

Transducer Diagnostics - This is intended for use when requested by Garmin for troubleshooting purposes.

All of the Installation options have additional information listed in the owner's manual for the chartplotter.