Fishfinder problems

[fishaholic20]

I recently installed a new fishfinder in my boat and have been having some problems with it. The fishfinder accurately marks the bottom when you look at the bottom line on the screen compared to the depth chart on the side (not sure if that makes sense). However, the numbers that indicate the depth are erratic and constantly jumps from the actual depth to depths that are too deep. The depths read properly when moving at high speeds, but not when drifting. Is my transducer set up properly and is there anything I can do to resolve this problem? The transducer is mounted on the transom.

Thanks

 

[dingbat]

Re: Fishfinder problems

What is your gain set at?

 

[fishaholic20]

Re: Fishfinder problems

I'm not sure about the grain. Does the grain make a difference and what should it be set at?

 

[ziemann]

Re: Fishfinder problems

We need more info-

Brand/ model of Fishfinder- depth of water that this occurs at?

digbat is asking because most FF's have a way to adjust their sensitivity and that will most likely fix your issue. Some FF's have a tough time reading extremely shallow water- thus if this is only happening when you are tied up at the dock, you may be fine on the water. It is better to do the adjusting of the units sensitivity when you are running in normal water and not sitting at the dock. Is the water particularly turbid?

 

[john from md]

Re: Fishfinder problems

Do a search using there are quite a few posts where folks have had problems with their fishfinders reading erratically in shallow water. Mine was never reliable in less than seven feet of water.

John

 

[fishaholic20]

Re: Fishfinder problems

Sorry guys. I guess I should've mentioned this in the original post; the FF is a Humminbird 343c. I use it in a shallow river, no deeper than 10 feet, so don't really know how it acts in deeper water. The river is pretty swift and turbid in some places. If it is a problem with the sensitivity, do I need to increase or decrease the sensitivity in shallow water? I believe it is currently set at a lower sensitivity level.

 

[kandil]

Re: Fishfinder problems

you should change the setting and experiment with deferent setting until you find the right setting for your fishing area did you install the transducer in a good location correctly? check the installation manual that came with it or you can post a photo of your transom.
What is your transducer KHZ? you need 200KHZ for shalow water

 

[a70eliminator]

Re: Fishfinder problems

Could be your transducer is not exactly horizontal to the bottom when at rest drifting then when up on plane it's horizontal, are you getting a double bounce echo this will cause the depth to double randomly if the sesitivity is too high, if the depth changes by only a foot or two thats normal in waves two feet or more.

 

[fishaholic20]

Re: Fishfinder problems

Yes, the transducer is 200KHZ. The reading will jump from 6 to 15 feet, not just a foot or so due to waves. I was thinking the same thing you were, eliminator, but it can only be adjusted up and down and can't be tilted back and forth. I guess I'll just have to play around with the settings more and see if that takes care of it.

 

[rdny041285]

Re: Fishfinder problems

I mentioned something like this in another thread but i also have the humminbird but its a 595C and seem to be having the same issues. Only difference is that mine operates in the ocean. Works fine for a while and then all of a sudden it starts bouncing like a bouncy ball 1ft then 300ft and then back....never goes back to normal until the next time i take it out. anyone that knows how to fix this would make me very happy.

 

[John_S]

Re: Fishfinder problems

Yes, the transducer is 200KHZ. The reading will jump from 6 to 15 feet, not just a foot or so due to waves. I was thinking the same thing you were, eliminator, but it can only be adjusted up and down and can't be tilted back and forth. I guess I'll just have to play around with the settings more and see if that takes care of it.

Crank the sensitivity down. It sounds like you are in shallow water, probably with very hard returns (rocks, gravel) where the initial signal return reflects off the surface and back down again. Typical to have a doubling of actual depth.

 

[Shizzy]

Re: Fishfinder problems

I have always turned the sensitivity way down and then snuck up on the best setting. I have better luck then starting with it turned all the way up and backing down. I do the same with my flasher during Ice fishing season.

 

[jhealy748]

Re: Fishfinder problems

I have a 917C and had this problem and it took me a while to figure it out too. I'm not sure if it will work to fix your problem in shallow water but for those of you having problems in the ocean and deep water there is a setting somewhere for max depth and if you are deeper than that setting it will bounce from 1 to 300 and all around until you get back into that range. just change the setting to as deep as it will go!