What would cause depth finder to suddenly read shallow water?

viper1216

Chief Petty Officer
Joined
Jul 31, 2013
Messages
420
I was out yesterday and while under way, my depth finder on my Garmin suddenly read 1.3 ft of water and the alarm went off. On instinct I immediately throttled back. I have a second depth gauge on my boat and when I looked at that one I was in 55ft of water. Figured maybe my transponder was being funky, but then a bit later, they BOTH did the same thing and I know I was still in 60+ ft of water. I was following behind a giant tug boat, and there was no way he was in 1.3ft of water. Water was relatively calm, a little chop but nothing crazy and was going about 20mph.
 

Grub54891

Vice Admiral
Joined
Jun 17, 2012
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5,908
Could be low power to the units, or you picked up some debris that made them read wrong. The debris could have fell off before you checked back there.
 

dingbat

Supreme Mariner
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Nov 20, 2001
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15,417
The much revered "false bottom"......doubtful

Could have picked up the prop wash of the tug or a school of fish
 

Rookster

Petty Officer 1st Class
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Mar 12, 2017
Messages
226
Interesting - I had the opposite happen to me...in about 10 feet of water on the weekend, my depth finder suddenly said 55ft for a few seconds before correcting itself. Impossible since the max depth of the lake is only 30ft. I agree that temporary conditions underwater can distort the readings sometimes. In your case, debris sounds right. In my case, perhaps an air pocket.
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
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Jul 23, 2011
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maybe this was below you
brXX_1909879_2_px_640_.jpg
 

viper1216

Chief Petty Officer
Joined
Jul 31, 2013
Messages
420
Lol, there was a giant Great White spotted off the coast of Cape Cod the other day, maybe it was him :) My son was eating Cheetos and I hear they like those. I am thinking debris then as well, my Garmin did it multiple times both before and after I was behind the tugger. But the one wired directly to the boat was fine except that one time, when I was behind them, so thinking churned sea for that one. The transducer for the Garmin is on the back of the boat, but the one that came factory installed on the boat is on the bottom.
 

NightAngler

Cadet
Joined
Jan 2, 2016
Messages
16
Wonder if the transducers are interfering with each other..I suppose you tried turning off the unit indicating 53' to see if the Garmin changed it's reading to same. If it's only happening during speed..perhaps air bubbles are crossing the transducers path?? Good luck, less a faulty unit.
 
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