Over the weekend at the Pasadena fishing show, I bumped into a buddy who needed some fishfinder help. Seems that when he pulled his boat this fall, he knocked the transducer out of whack. He might have been upset, except that it needed an adjustment anyway because whenever he broke a plane, the fishfinder screen went blank. When I swung by his house and took a look at the unit, the reason why was obvious – he’d mounted it a full inch lower then the hull bottom of the boat, so it caused turbulence when he got some speed up. It’s a common problem; transom-mount transducers can’t be too high nor too low (about 1/8 of an inch below the hull bottom is about right) or they won’t perform well. If your fishfinder blanks out at high speed, there’s a good chance improper mounting height is the reason why. And if you’re not satisfied with its performance, try these tricks to get it working right:
2. Check Frequency Frequently – Many units have two frequency settings, and often they get changed to low (usually about 50-khz) by accident. In 90% of common fishing applications it should be set to higher frequency (usually about 200-khz). Only try low when you’re in water 300′ or deeper, and often, high frequency works best until you go deeper then 600′ or 800′.
3. Go Auto – Most modern units have extremely good auto settings, and the machine can tune in all by itself better then you can. In most cases, auto mode will give you a better reading then custom settings.
4. Unless… – One exception to this rule is in ”goopy” water with mixing densities. In the Chesapeake during the summer, for example, a montague of jellyfish, algae mixing salt and fresh flows, and temperature barriers tend to confuse auto modes. In this scenerio, go manual and tone down sensitivity until the screen cleans up.
5. Sensitive Skin – When you do have to tone down sensitivity and go manual, use a 6-ounce lead jigging spoon to test it; this type of spoon presents an excellent return on fishfinders, and by dropping it overboard right next to the transducer you can “look” for it, and decrease or increase sensitivity as necessary, until you see the spoon without seeing clutter.