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Tips, Tactics, and Tackle

Fish Finder Tuning
By TomT
Dec 22, 2004, 13:30

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The key to getting the most information from any depth finder is in learning how to peak the transducer. Too much power will fill the screen with clutter and overpower the machine. Too little power will not show such important underwater features as thermoclines, schools of baitfish and even game fish. The gain or sensitivity knob controls the signal power output of the unit. The first step in peaking the transducer is turn off any automatic gain controls the unit might have and go to manual control of the power output. Now, select a deeper depth range setting than the actual bottom depth. If you're in 300 feet of water, set the depth range for 900 feet. If you're working shallower, say in 60 feet, set the range for 180 feet. Tripling the actual depth is necessary for this operation.

Start to turn up the power gain. First, you'll see the bottom, which only makes sense since the harder and larger the object, the stronger the return signal. The ocean floor provides a solid return. Continue to increase the gain until you get a "second echo."

The second echo is nothing more than the return signal bouncing off the bottom once and then having enough energy to make the trip back to the bottom and up again to the transducer. The second echo shows up on the screen as a second bottom reading at double the depth of the real bottom. The screen will now be showing a bottom reading at say 250 feet and another bottom reading at 500 feet. Now you can understand why you need to have the depth range set at triple the actual depth to accomplish this procedure.

Once you have a strong second echo reading, you can return the unit back to the normal depth setting for actual fishing conditions. You have maximized the power being sent through the transducer so you will be able to acquire the most information from the depth finder screen. You will begin to notice things on the screen that you were missing on lower power settings or on an automatic sensitivity mode. You'll mark fish, bait, temperature changes in the water column and more.

Do realize that once you peak the transducer for a specific depth range, you have only about a 20 percent window in actual depth before you have to repeat the procedure. In other words, if you peak the unit while fishing in 200 feet of water and you begin moving into deeper water, say into 300 feet, you will have to repeat the procedure for the deeper water.

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