How to Stop Interference Between Two Depth Finders

How to Stop Interference Between Two Depth Finders
If you use a fishing boat with two depth finders, you may encounter some problems with signal interference. Depth finders use sonar -- sound waves -- to bounce off the bottom of a lake, bay, river or ocean. The sound wave returns to the depth finder, which translates the signal into data for display on a monitor mounted on the dashboard of a boat. If two sound waves collide or become blocked by other vibrations in the water, the signal interference can scramble monitor readings. Follow these steps to stop the interference between two depth finders.


Difficulty: Moderate

Things You’ll Need:
  • Boat Two depth finders
  • Boat
  • Two depth finders
Step 1
Switch off one of the depth finders while using the other. If one depth finder is dedicated for navigation and the other is used for fishing, turn off the fish depth finder while navigating.
Step 2
Shut off the trolling motor while using the depth finder. A combination of two depth finders and a trolling motor operating simultaneously is a recipe for confusion. The depth finders are reading each other and the vibrations from the trolling motor. The result is a scrambled signal.
Step 3
Rearrange the transducers below the boat. Transducers send the sonar signal into the depths and receive the return signal for translating depth onto the viewfinders on the boat. They are typically attached to the stern and the shaft of the trolling motor. Moving the transducers to another location, or simply adjusting them to point slightly away from each other, may cut down on interference.
Step 4
Adjust the sensitivity controls on the depth finders. Turning the sensitivtiy dial from 85 percent to 75 percent or lower could eliminate interference with the second depth finder.
Step 5
Switch off other electronic devices on the boat while using the depth finders. Turn off the radio, the wind-screen defroster, running lights and any other powered device to see if the interference goes away.

Article Written By James Clark

James Clark began his career in 1985. He has written about electronics, appliance repair and outdoor topics for a variety of publications and websites. He has more than four years of experience in appliance and electrical repairs. Clark holds a bachelor's degree in political science.

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