Sonar help please

[Tomcat]

Thanks Art for your explanation. There's lots of expertise in our OFC community and I'm thankful you shared some of yours. I finally remembered reading an article about blind areas within a sonar cone. Took me a while to find the article again - see http://www.vexilar.com/help/tips/tip006.html The vexilar article provides a plausible explanation of why my colleague could catch keeper walleye (vertically jigging while anchored) without marking any fish on his sonar. Here's a great descriptive picture from the vexilar article:

 

The vexilar explanation:

 

The Dead Zone is the area within the transducers cone of sound that is blind to you. The wider the beam angle the greater the possible dead zone. The sonar will mark bottom as the nearest distance it sees. If you are fishing over a slope it may see the high side of the slope, at the edge of the cone, and mark that as bottom. The fish that are hanging on the bottom in the center of the cone will be invisible to you because they are actually within the bottom signal on your depth finder.

[Zib]

If fish ID was turned on then that may be the reason he wasn't having fish show up on the bottom. Fish ID is nothing more than a marketing ploy to help sell the unit. You should always have fish ID turned off to get more detail of the bottom. Was he using bottom zoom?

 

Always make sure that the sensitivity is turned up just enough so that you have interference on the top of the screen. The transducer should be mounted a foot away from the motor as well.

 

If anyone is considering getting good sonar then buy a unit that has a minimum of 480 vertical pixels. You will pay more but it will pay off when you locate & catch more fish.