Losing depth readings on my Garmin chartplotter at high speeds

There are several reasons you might lose your depth reading when travelling at high speeds. It could be related to the transducer's mounting location, device settings, or you could be outrunning the return signal if you are moving too fast.

If the transducer is mounted on the transom, here are a few troubleshooting steps to follow:

• Transom mount transducers will not work at any speed if they are installed on a powerboat with inboard motors, or any sailboat.
• If you have a single engine outboard, or Inboard/Outboard, make sure that the transducer is mounted on the starboard side of the boat, so it is free from most propeller wash.
• If you have a twin, or triple engine outboard, or Inboard/Outboard, make sure that the unit is mounted between the motors, as low as possible, either on the flat section of the keel (if any), or slightly left or right of the vee.
• If you are still seeing poor performance at speed, this usually indicates that the transducer needs to be mounted lower so that face of the transducer is in contact with the water at speed.
• To make this adjustment, loosen the mounting screws, and slide the transducer 1/2" lower and re-test. You may need to drill new holes. If you do so, be sure to seal the old holes with a manufacturer approved sealant below the waterline. Some recommended sealants are Boatlife, Sikaflex, 3M5200, or 3M4200.

If the transducer is a thru-hull transducer, this could also be an indication that air bubbles are flowing over the transducer. Re-locating the transducer may help in this situation. Some thru-hull transducers have a High Performance Fairing Block (not offered for GT and CV transducers) installed, which is designed to improve a transducer's performance at speeds above 17 MPH. The elongated, streamlined shape of the fairing block cuts smoothly through the water, resulting in fewer air bubbles flowing over the transducer's face.

Another troubleshooting measure to try would be to adjust the following settings:

• Adjust the Gain setting on your device. Leaving the Gain setting on Auto will not guarantee that the device will receive a signal at any depth. The Gain may need to be reduced or increased manually.
• Change the Frequency setting on your device if using a dual frequency transducer. The higher frequency setting is generally used for shallow depths where the lower frequency setting is used for deeper waters.

Keep in mind that some makes and models of boats do not always allow depth readings at high speeds.