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Author Topic:   SONAR Readings In Less Than 3-Feet of Water
jschmidt63 posted 01-23-2007 05:36 PM ET (US)   Profile for jschmidt63   Send Email to jschmidt63  
[I] hooked up a [Humminbird] Matrix 17 on [a Boston Whaler] Katama this past fall with a transom transducer set per instruction. I ran the wire along the gunwale because I was originally getting interference using the rigging tunnel. Made sure mininum depth is to menu setting of 1 (lowest you can go). The display always messes up if I get shallower than 3.5-feet. I get good bottom readings [in water deeper than] 3.5-feet but when I reach this depth it is just a screen full of lines. Generally okay if deeper than 3.5-feet unless going fast. It is just the shallow water.

[Give] suggestions or [report] similar problems.


an86carrera posted 01-23-2007 07:39 PM ET (US)     Profile for an86carrera  Send Email to an86carrera     
My Humminbird Matrix 97 goes to 2-feet then flakes out.

Maybe customer sevice can help.


jschmidt63 posted 01-23-2007 09:55 PM ET (US)     Profile for jschmidt63  Send Email to jschmidt63     
I left a detailed email message with Humminbird tech support. Let us see what they say. I also added that if I cannot resolve this issue the unit will be sold and I will purchase a Garmin.


an86carrera posted 01-23-2007 10:14 PM ET (US)     Profile for an86carrera  Send Email to an86carrera     
I have a personal contact there let me know if you need it.


WT posted 01-23-2007 10:27 PM ET (US)     Profile for WT  Send Email to WT     
I'm wondering why you need to have your fishfinder read in less than 3.5 feet of water. Can't you see the bottom or the fish in this shallow of water?


bms1939 posted 01-23-2007 10:56 PM ET (US)     Profile for bms1939  Send Email to bms1939     
Does your unit have a keel offset feature? You can adjust this to read actual water depth or the depth from the bottom of your boat. Prop wash in shallow water can interfere with the signal, try it at rest. Make sure your transducer is at the proper angle. Just a few thoughts, good luck.
an86carrera posted 01-23-2007 10:59 PM ET (US)     Profile for an86carrera  Send Email to an86carrera     
Good suggestion. Offset
bms1939 posted 01-23-2007 11:11 PM ET (US)     Profile for bms1939  Send Email to bms1939     
I just went to the Hummingbird web site, your unit has the keel offset feature. It shows how to adjust it on page 46 on the online manual. This unit also comes with an optional dual frequency transducer, Make sure your using the right setting for shallow water, I believe 200 is the proper setting.
jschmidt63 posted 01-26-2007 05:02 PM ET (US)     Profile for jschmidt63  Send Email to jschmidt63     
Thanks for your help! Will check my settings. WT: it is hard to visually judge water depth when it gets shallow, that is for me at least. It can also change really fast too when cruising in the Chesapeak bay.

Also, I received a response from tech support:

"John--The unit should work in shallow waters over 2.5 feet. You may want to adjust your noise filter, and your surface clutter filters while you are in the shallow waters as this may correct the problem you are having when you are in 3.5 feet of water.
Kind Regards,
jimh posted 02-03-2007 09:21 AM ET (US)     Profile for jimh  Send Email to jimh     
You may need to make some adjustments to your unit. Most of these devices have many controls which can affect their operation. If you want to optimize the results for very shallow water you will likely have to alter the settings from the default position.
jimh posted 02-03-2007 09:30 AM ET (US)     Profile for jimh  Send Email to jimh     
Also, in shallow water you will generally only be able to use the device as a depth sounder. The beam of the transducer's sound wave is very narrow and you won't see anything but a bottom echo unless a fish happens to be directly below the transducer. At three feet the beam spread on a transducer with a 20-degree cone angle is only about a foot.

You don't mention the frequency of your transducer, but generally a 50-kHz transducer is intended for deeper water and won't work as well in shallow water as a higher frequency transducer. This may be affecting your results.

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