Only time I had mine give me false readings is when I had ice on the transducer. Cleaned it off and all was fixed for me.
Did you try it in more then one hole?

chad1

 

Are you sure you were reading bottom and not weeds or fish, or someones spud sticking staight up from the bottom?

 

I thought of weeds myself but 6' are allfull tall weeds.

 

How deep of water were you in?

 

I have gotten false readings when my transducer has not been below the ice as well.

Was it on the correct setting for the depth of water you were in, that could lead to a "false bottom" I think?

A question for anyone to answer: Ever used your Vex in smelt town? I did two weeks ago and was wondering if the lights had any impact on it? I seemed to be marking fish throughout the whole water column (possible-yes)(probable-no). We caught about 70 between 4 of us, but if there were that many below us I would imagine we should have done better. Just trying to learn for next time. Thanks in advance.

 

It could have been weeds, but we never hooked any. We checked to make sure the ducer was below the ice. It may have been ice on the ducer.
What is it like fishing in weeds, is it alot harder to see the fish, do the weeds just cover the bottom few feet so you can't really see fish moving?
Just curious.
We should have tried in another hole in the same area. We fished ealeir in the day about 100 yards from there and had no probs with bottom
thanks

 

Well the beam had to be hitting something, if you had your gain and range set correctly. If you are on a steep drop off your vex will mark the highest point on the slope that the beam hits. This creates a blind spot...which you could also describe as a false bottom i guess. So when you let your lure down it goes deeper down the slope of the drop off than the vex is marking.....thats my guess at what you were seeing....it has to be a really sharp slope like a river channel edge to create that large of a blind spot though. Oh yea...if its the drop off problem switching from 19 degree to 9 degree will help eliminate some of the blind spot. .......weeds...fish...ice on the ducer, not hanging the ducer low enough...not having the ducer level..etc...have to be there to really try to figure it out...sounds weird though.

 

Sounds simple, but took me some time to figure out with mine. First, i got the adapter for my 8 to help reduce false bottoms and other this in shallow water. Second, befor that I has similar probelms and between 3 feet of weeds, and my not taking into consideration the differance in height between where I was measuring my line (top of the ice) and where the transducer started (2 -5 inches below the ice) I found my missing depth. Counting that extra 10 inches of ice a 2 foot of snow makes a worl of differance.

 

Had the same thing happen the last time we went out and it turned out to be a school of crappie. Fixed that problem really quick.

 

If you were on a sharp drop-off you can get the same thing, almost a dead zone. The instruction book can really be helpfull when first using the unit. Also if your gain is to high with the thick ice and snow it can get alot clutter. Try adjusting the gain to read your lure as a small or thin line maybe a little orange when jigging it. Hope this helps you out.

 

I have to agree with Scottyhoover's post. If you are at a steep dropoff in deep water you will have a wide cone for your sonar. The first thing it hits will be the top of the dropoff which can be several feet away from your hole. This will look like a false bottom. I think this is one of the differences between the FL8 and 18 is the ability to narrow the cone. I think you can also purchase other transducers. Anyway, trying another hole would have probably answered the question. Lowering the transducer down several feet might also resolve the dropoff problem by narrowing the area.

 

I've gotten a 'false rising bottom' throughout the night when fishing smelt, could never figure it out until the bottom went from 60' to < 5', I looked down in my hole to see so many smelt it finally made sense. many small bodies probably bounce that signal around enough to give a false bottom reading. Ever since, when fishing smelt, I see the same thing happen, seems I always start deep and by midnight am fishing 5-20' in the water column.

 

Having used very sensitive depth sounding equipment, false readings could be do to several factors. One is the possibility of an echo. A hard bottom will bounce the signal, which again could be bounced from the ice. Secondly a temp change with is quite possible on deeper waters. The thermocline which is usually established in the lower water column will attract micro organisms and in turn give a reading. Try to reduce the sensitivity and see if that removes the (false) reading.

 

I thought I had the same thing happen yesterday when I was fishing a gravel pit, tunred out the goofy marks that were 5 foot down over 22 were Crappie cruising all over heck. I have had that happen before and just ignored it until I finally decided to get off my fat butt and look down the hole.

 

Here's a picture of what Scotty was describing.

 

The dead zone is probably the reason , but one other thing that will cause that is jumping holes without shutting it off, and then turning it back on, while you have the Auto zoom on, at least with the Fl18 anyway

 

If you have a duel cone transducer you can narrow the cone if you fish a drop off.

Would be interesting to test it out with another unit.

I agree with Tubejig, I have had that happen with a school of crappie.

 

YOU cannot narrow your cone, whatever transducer your using is what you get. you can have the dual transducer however 9 and 19 degree. You can buy transducers that are 9,12,19 and they work on all vexilars

 

Call Vex and have your serial number handy. There were a lot made that need a revision made. I bought my fl18 last year, and I had to send back the electronic modual for an update. One of the symtoms was reading a false bottom.
If yours isnt in that catogory, you are probalby reading the dead zone like others have said.

 

Good question. I have seen this "false bottom" on my fl8 as well. In different places on the river. I can watch my lure go down, and once its passed the red line, it goes for another foot or so.

I'll keep an eye on this post, see what others have to say.

 

I have seen what you described as a false bottom a few times. One time was from a large, sharp looking boulder directly under me. Another time was from being directly over a gaurd rail on a submerged bridge. The gaurd rail looked like a solid 2' high red band. The there was a little opening between it and the "true" bottom.

(Seeing underwater with a camera positively identified these features.)

Just remember that the "bottom" to a vex is not one point but a wide area and it will show you all the high and low points in this area, although they get all mashed together and hard to decipher sometimes.

Changing locations would have definitely helped to figure out what was going on.

PS as for the weeds and what do they look like, to me they look like fish and they are kind of hard to figure out, because they are swaying in the underwater currents, so they look like fish swimming around, but never completely leave the screen.

Ive used a vex for 2 seasons now and Im still learning and Im really impressed with them!

Lastly, THANKS GUYS!!! Ive been checking this site out a lot this season, especially when you all had ice and we icers down here in Ohio were throwing ice cubes into our lakes!! You guys are really informative and I wish you all great luck fishing!

 

Gillslayer:
I have some questions that I haven't seen asked.
How deep was the bottom where you were at?
Did you have a second echo (red mark) and how deep?
Did you see your lure below your "false bottom" or did you go by the amount of line you let out past the bottom?

If the bottom there is on a drop off the vex will show a wider red mark and you won'r be able to pick out your lure. If the water is shallow enough for weeds they could be tall enough to bend over in the currents and give you a reading above the bottom reading. lastly there could be something laying on the bottom and angled up right where you happened to be and showing a reading above the real bottom.

 

lastly there could be something laying on the bottom and angled up right where you happened to be and showing a reading above the real bottom.

Hmmm ... like the log I snagged with a jiggin rap last week!! Ah well ... another $6.00 down the drain.

 

Just rember there are alot of vairables, I have used a vexilar for 12 years now and I go 3-4 times a week, you do the math. The unit will show the highest spot if your on a drop off, and your lure will go below it, thats a dead spot not really a false bottom. It depends on how your gain is set, It's your job to determine what it all means, just like a computer, it can only do what you ask it to.I mean stop and think about it, the unit does not really show fish, it shows whatever is between bottom and the surface, weather it be fish ,a high spot like a rock or whatever, zooplanken, minnows, ect. It's a stupid machine and we have to determine what it's showing us to help us catch more fish. It all comes with expericence, good luck.