Most of you have probably invested a lot of your hard-earned dollars on a quality fish finder. Good move - nothing has revolutionized sport fishing in the past half-century as much as the arrival of quality sonar.
Now here's the big question: are you allowing yourself to be misled about what the sonar says is beneath your boat because of a simple, yet common, error most fishermen make when on the water using the devices?
That issue is paramount because we are entering the time of the year when fishing for bass vertically will be the dominant pattern, and having confidence in what the sonar says is under your feet is vital.
I have "graphs" or fish-finders on the front of my boat that cost many thousands of dollars, so I want / demand accurate information about what is directly below the transducer mounted to the bottom of my trolling motor. It's a reasonable demand and it's one all anglers should make.
Between the fall turnover and the arrival of spawning season a huge number of bass will take up residency in depths of 40 to 80 feet of water. I find that they are actually easy to catch...once you "see" them on your graph, but here is where the problems begin.
Your graph displays the water column through which your transducer sends out its signal, but is that signal aimed in direction that is NOT straight down?
Many fishermen are "seeing" a display on their graphs of an area that can be twenty feet or more away from what you think you are seeing simply because your transducer is shooting at an angle.
"But I carefully mounted the transducer myself," many argue. "I did it in my garage and I could see that the transducer pointed straight down."
That is the source of the error so many fishermen make; they assume their transducer is sending out a signal that goes straight beneath their boat, but quite often it isn't. They equate the set up they built in the garage is the same one that exists when they are afloat.
Not always, but here is how you can tell if your set up is true and then make any needed adjustments.
Take a buddy as well as two levels (the kind a carpenter uses when building a house) with you to the lake. I use one that's 48-inches in length and one that's 24-inches long. I use red marker to color a small spot on each level so I know which side is "up" when I make my comparisons.
(See photo accompanying this blog.) Once the boat is in the water lay one level across the front of the boat, with the red mark up, from starboard to port. Lay the second level, also with the red mark up, perpendicular to the first level.
Now stand on the forward deck as if you were fishing. Have your buddy mark with a pencil on the level itself where the bubble is located. Do that for both levels.
Don't be surprised if the levels are not centered because your weight on the front deck has probably caused the bow to tilt down towards the water, but that is exactly what leads to erroneous information being displayed on your sonar unit.
If you are looking for fish in 50-feet of water and your sonar cone is tilted out of perpendicular because you didn't consider your body weight when setting up your transducer, you will waste a lot of time trying to catch fish that don't want to swim twenty feet or more to get your drop shot presentation.
So what's a man to do? Here's the solution.
Return home, place the levels back on the front deck of the boat and duplicate the boat's position by finding a parking spot where the levels match the marks you made while afloat. You may need to use pieces of lumber placed beneath the trailer tire on one side to match the left-right angle and the boat tongue jack to duplicate the forward-aft pitch of the boat.
Now you are ready to lower your trolling motor and adjust your transducer. I point the motor forward (then on the lake I know my best position) and make sure my transducer is pointed straight down.
You are now ready to fish with confidence. Your fish finder is now accurately telling you what lies beneath your boat, and you will probably catch more of those deep bass as a result.
Enjoy.
