Author Topic: Inconsistent depth problem  (Read 3110 times)

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Offline nitroman74

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Inconsistent depth problem
« on: May 24, 2013, 01:13:15 PM »
ila_rendered  Has anyone ever seen this problem with incorrect depth reading while looking at their navigation screen


Offline ITGEEK

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Re: Inconsistent depth problem
« Reply #1 on: May 24, 2013, 02:04:50 PM »
The depth of your map card is not always going to exactly
match the depth of the water you are in.
The water levels of all bodies of water will
fluctuate depending on rain fall.
In times of drought, water is drawn from some reservoirs for
drinking purposes.

Also, when the map cards are created, they are probably created using
some type of average water height.  Maybe average for 1 year or average for
5 years.  Who knows?

There are also map card errors, and GPS positioning errors to take into account.
« Last Edit: May 24, 2013, 02:15:19 PM by ITGEEK »

Offline Rickard

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Re: Inconsistent depth problem
« Reply #2 on: May 24, 2013, 02:08:43 PM »
I think your unit doesn't have a bottom lock where the bottom actually is. The unit has found a strong return close the surface, perhaps from a part of your boat, that fools it.
 
Rickard

Offline rdstair

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Re: Inconsistent depth problem
« Reply #3 on: May 24, 2013, 06:31:51 PM »
I have a 1198 and 998 with a Lake master  chip. It gives me the option to adjust water level. Not sure if this helps.

Offline Humminbird_Greg

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Re: Inconsistent depth problem
« Reply #4 on: May 28, 2013, 10:36:37 AM »
The map and its data have nothing to do with this guys.  Rickard was right: there is a sonar return close to the surface that is fooling the unit into thinking it is the lake bottom.

Welcome to the Side Imaging Forums nitroman74.  Try adjusting your Surface Clutter menu higher and see if that clears anything up.  If not:
What transducer are you using with your 788ci when this happens?
Where is the transducer mounted?
Is the 797 unit you list under your name on at the same time?
Does it also show this or does it read correctly?
Can you try swapping the unit around and see if they do this on the other unit’s transducer?
Greg Walters at Humminbird
gwalters@johnsonoutdoors.com


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