Lowrance problem reading depth greater than 20ft

I am having a problem getting a depth read at depths greater than 20ft. This unit is mounted on my trolling motor. I also have a Humminbird Matrix 67 on the console with a transom mounted transducer. The console reads fine but the bow is reading erratically. Any suggestions?

Welcome to the site Cull;
I can’t help ya, but there are a number of good Lowrance guys here that maybe be able to help you trouble shoot.

Also, try and get ahold of Wade at Jolly Ann Marine, here on the site. He is pretty knowledgeable about Lowrance.

Is it wired to the same battery as the trolling motor? Is it happening only when the trolling motor is on? Does the depth on the screen jump up and down? How old is the transducer?

What kind of transducer are you using? Skimmer, puck, or a universal one built into the trolling motor? I’ve seen problems on the MinnKota universals where air bubbles get trapped when you deploy the trolling motor which causes some pretty eratic returns if you get anything at all. Other things to check would be the angle on the transducer and if there are any big gouges in it.

I talked to Lowrance at the end of last week and they told me that it may be interfereing with the Humminbird I have on the console. They told me to turn off the Humminbird and try the Lowrance on the bow by itself. It seem to fix the problem. Although it seems strange to me that my buddy, whom I bought both units from, could have the exact same setup as myself with the exact units and be able to use them at the same time. I have been on several boats where people run both sonars and have no problems why me?
To answer your question I have a new skimmer on the trolling motor. I get a bouncing read if the console unit is on. If I turn off the console unit it works perfectly. The trolling motor doesn’t seem to effect it.

I forgot to mention. I have the unit wire into the fuse box. Lowrance had me go into “Overlay Data” and display my voltage on the unit. I am getting anywhere from 10.9-11.3v. They said it should be around 12

Since turning off the one unit solves the problem, it would seem that it is interference from the two transducers, most like on very close frequencies. You don’t notice it until about 20 feet or greater depths, because the cones from the transducers don’t overlap in shallower water.

I have heard of some success in changing ping times helping to alleviate some interference problems, however I’m not aware of how to do that. Hopefully someone else can share a bit more info. Good Luck, let us know how you come out.

dave