For what it's worth. I have to two lowrances and a humminbird side imager. Some of the things I notice fishing in several different lakes; Here in tennesse, I get great pictures from my dash mounted Humminbird and Lowrance. Very little "nusiance" returns. My trolling motor graph is different. When I first got it, it worked great. Now that it has hit a few logs, bottom (and a 20+lb stripe!), it has some nicks and gouges. I get a heck of a lot more nuisance or ghost returns like your picture shows from the front. This weekend I am going to sand it and buff it to see if it stops, I will let you know.
The other thing I learned was this past weekend fishing in the Harris Chain. The majority of the lake is 7-10feet deep in the middle, although there were gredge holes down to 20-25feet. I had so much "crap" showing on my graphs. I had to reset all of my settings and lower the sensitivity to elminate the "columns" like yours is showing. I only got them when I was in less than 10 feet of water, but after adjustment, they went away. Harris chain also has solid clay bottoms and when you are sitting on them in 5 feet, you can imagine how much echoing is going on.
It's funny, I was able to see/hear a class put on by Wilson Fraizer (
http://www.itainttv.com/index.php). He stated that with todays electronics, you want it on "auto" a lot more because the strength of the signals and what is returning the signal can create a lot of nusiance returns (5 feet sensitivtiy is a lot different then 25 feet sensitivity). If you are new, he suggests you leave it on auto until you get used to changing it for different depths.
I suspect you have a nusiance return, particurlarly if you can't recreate it in the same spot. If it is a nusiance, check for damage to the wiring and transducer. If you have a shoot through, see if you can "borrow" another one, hook it up and see if it goes away. If it's is that much problem, by using some sort of elimination, you can probably figure it out.
just suggestions if you get them alot.
Fuzz
