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Improving Returns on Garmin Traditional, ClearVu, and SideVu Sonar

Notes:   
   • See Garmin Marine Device Shows No Sonar Option or Depth Reading for troubleshooting steps if there is no sonar option or depth reading.
   • See Troubleshooting Poor Returns with Panoptix LiveScope for steps to resolve LiveScope sonar quality issues.

If the traditional sonar, ClearVü™ sonar, or SideVü™ sonar views show unclear images or fails to display targets on a Garmin chartplotter or fishfinder, they could be impacted by one or more of the following factors:

  • Cavitation, or air bubbles going across the transducer that interfere with sonar readings

    • This may be caused by boat speed, transducer placement, or water turbulence

  • Transducer condition

  • Transducer frequency

  • Trolling motor noise

  • Water clarity

Before troubleshooting the device, disable the zoom or bottom lock by selecting Menu > Zoom on a sonar page.


Sonar settings

Changing water conditions can have a significant impact on the clarity of a sonar reading or its ability to display targets of certain sizes. Some settings can be adjusted to compensate for this:

Sonar settings

    • Edge: highlights the the strongest signal from the bottom to help identify its hardness or softness

    • Gain: adjusts the transducer's sensitivity

      • Increase the gain in deep water and higher speeds

      • Reduce the gain in shallow water and slower speeds

      • If the sonar display fails to pick up all returns, increase the gain until it shows the returns, then reduce the gain to the preferred level to reduce noise

    • Interference: reduces the effects of interference from nearby sources of noise, such as a trolling motor

      • Use the lowest interference setting possible

      • If the highest interference setting does not resolve the issue, the transducer installation may need to be adjusted

    • Range: the specified depth of the water column shown on the sonar display

      • It is recommended to set the range to Automatic to allow the device to track the bottom

    • Surface noise: hides noise on the surface to reduce clutter on the sonar display

    • Time-varying gain (TVG): reduces surface noise and the appearance of returns to compensate for weak sonar signals in deeper water

      • Increased TVG will make the colors associated with fish targets and low-level noise appear more consistent in various depths

    • Ultra-scroll: controls the scrolling speed of the sonar readout

      • Ultra-scroll is not available on all devices

Some transducers give the option to change the frequency to get better returns in certain water conditions or for targets at certain depths:

    • The lower the frequency, the deeper the sonar's range

    • The higher the frequency, the clearer the image

    • Higher-frequency sonar readings can compensate for surface turbulence

See the device's owner's manual for steps to adjust sonar settings.


If necessary, the sonar settings on the marine device can be restored to their factory defaults.

Steps to restore sonar default settings

To restore sonar default settings on a STRIKER™ fishfinder:

    From any sonar page Press the Menu bar icon transparent Menu button > Sonar Setup > Restore Sonar Defaults > Yes


To restore sonar default settings on an ECHOMAP™ chartplotter: 

    From the sonar screen select Menu > Sonar Setup > Installation > Restore Sonar Defaults > Yes


To restore sonar default settings on a GPSMAP® chartplotter: 

From the sonar screen select Options > Sonar setup > Installation > Restore Sonar Defaults > Yes


The device will restore settings on all sonar views to default. 


Transducer troubleshooting

Transducer placement can have an impact on the clarity of a sonar reading.

General troubleshooting:

    • High boat speeds create cavitation that may prevent the transducer from picking up a sonar reading

    • If there are crimps or cuts in the transducer cable, the transducer may not be able to transmit information and will need to be replaced

    • The transducer must be clear of any fouling or scratches to get a depth reading


Mounting-specific troubleshooting

Select a transducer mounting type for troubleshooting steps:

Transom-mounted

    • The transducer must be level with the water's surface

      • Installing a transducer at an angle, regardless of the degree, will result in inaccurate depth readings and bottom returns

    • If using a boat with a stepped or V-shaped hull, mount the transducer on the lowest point on the hull

      • Transducers mounted above the lowest step may experience cavitation

      • Some boats may require a thru-hull transducer if the transom-mounted transducer experiences cavitation even on the lowest step

    • If using a pontoon boat, transom-mounted transducers will experience cavitation at lower speeds than most power boats

      • It is recommended to use a pole mount, a plate, or a thru-hull or in-hull transducer on a pontoon boat


Trolling motor-mounted

If the marine device has a trolling-motor transducer and shows a bottom reading but no fish or suspended targets, this may be caused by either transducer placement or noise from the trolling motor.

Transducer placement:

      • The transducer must be mounted correctly on the trolling motor

      • If targets begin to appear when the trolling motor is turned off, adjust the transducer placement

Trolling motor interference:

The vibration of the trolling motor can create interference on sonar readings from trolling motor-mounted transducers. To test whether or not the problem is caused by trolling motor noise, run the boat at speed and turn up the sonar gain to 100%. See the device's owner's manual for steps to increase the gain. If targets begin to appear at 100% gain, trolling motor noise is the most likely cause of interference at normal gain levels.

The following steps can help reduce trolling motor interference:

      • Connect the trolling motor to a separate battery from the Garmin marine device

      • Run the trolling motor and transducer cables in opposite directions

      • Use ferrite beads on the transducer cable.

      • Check for any corrosion to the trolling motor wires

      • Connect the trolling motor to a water ground, a grounding plate, or a post on the battery

      • Check the fuse of the trolling motor if it has one

        • Blown fuses can create electrical interference even if the trolling motor is still able to operate


In-hull transducers

    • The transducer must be appropriate for the boat's deadrise and correctly mounted

      • Go to garmin.com to search for the transducer and find the maximum deadrise on its Specs page

    • The transducer must be mounted in a solid fiberglass hull

      • 500 W in-hull transducers must be mounted in solid fiberglass hulls no more than 3/4 in. thick

      • 1 kW transducers can be mounted in solid fiberglass hulls up to 1 in. thick

      • The transducer will not work with cored fiberglass hulls, hulls with air spaces, or any other hull material

    • The transducer must not be mounted over any strake or other parts of the hull that will create turbulence or cavitation

    • If the in-hull transducer is in a fluid tank, check that the fluid reservoir is full and does not have a leak

      • If possible, fill the fluid tank with marine-safe antifreeze, such as propylene glycol, to cool the transducer elements


Thru-hull transducers

    • The transducer must be appropriate for the boat's deadrise and correctly mounted

      • Go to garmin.com to search for the transducer and find the maximum deadrise on its Specs page

    • If using a thru-hull pairing, check that the adapter cable is secure and has no visible damage

      • If necessary, replace the adapter cable

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