False Depth Readings - SailNet Community
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post #1 of 18 Old 09-23-2008 Thread Starter
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False Depth Readings

Returning from the Eastern Bay to Annapolis yesterday my depth sounder (B&G) several times started flashing the alarm and a two foot depth in waters 20- 45 feet.

I was wondering what might me causing it.. at first I thought of a school of fish but it happened several times so now I am wondering if the sensor unit is going bad. As an side I had the boat hauled and painted over the last week but not sure if that could be related to this.

Any thoughts?

s/v Mahalo
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Last edited by TAK; 09-23-2008 at 02:32 PM.
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post #2 of 18 Old 09-23-2008
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We get funny readings on ours sometimes too. I think ours sometimes gets a false echo off thermoclines as well as fresh water/salt water barriers and turbulance. I notice every time I put it in to reverse to set the anchor, it fouls up our reading. Weird.

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post #3 of 18 Old 09-23-2008
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turn the gain down and see how some of those false readings go by the board.

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post #4 of 18 Old 09-23-2008
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I have B&G Network Depth sounder and mine does the same thing when a stink pot goes in front and I go over the prop wash and when the botton is very weedy. I talkled with a B&G service guy that informed me that the transducer needs replacing to correct the problem.

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post #5 of 18 Old 09-23-2008
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yep cruzin up the coast of maine a couple of weeks ago ,in about 200 feet of water when the sounder started jumping up to15,25,40,5, etc what it was wuz tremendous schools of herring rising up to feed lolo with a fish type sounder u can see the fish and when ur used to it u can tell what kind of fish
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post #6 of 18 Old 09-23-2008
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Quote:
Originally Posted by norsearayder View Post
yep cruzin up the coast of maine a couple of weeks ago ,in about 200 feet of water when the sounder started jumping up to15,25,40,5, etc what it was wuz tremendous schools of herring rising up to feed lolo with a fish type sounder u can see the fish and when ur used to it u can tell what kind of fish

I'd vote for this as a possible cause. It's happened to me.


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post #7 of 18 Old 09-23-2008
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Quote:
Originally Posted by Boasun View Post
turn the gain down and see how some of those false readings go by the board.
Ok Mr. Fancy Pants
Cheaper depth sounders don't have any adjustments like this. Mine doesn't even have internal memory for alarm settings!
I feel much better using an inexpensive fish finder. Actually seeing the bottom inspires some confidence in the readings. Thermoclines etc show up but the real bottom is still there. Plus, all of them have fancy things like gain controls.
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post #8 of 18 Old 09-23-2008
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Ok Mr. Fancy Pants
Cheaper depth sounders don't have any adjustments like this. Mine doesn't even have internal memory for alarm settings!
I feel much better using an inexpensive fish finder. Actually seeing the bottom inspires some confidence in the readings. Thermoclines etc show up but the real bottom is still there. Plus, all of them have fancy things like gain controls.
To reduce false readings:
1. turn the gain down.
2. have matching transducer to your readout.
3. recognize thermal layers and bio masses.
5. Fish finders should be adjustable for tweaking for the optimum finding of FISH.

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post #9 of 18 Old 09-23-2008 Thread Starter
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Quote:
Originally Posted by Boasun View Post
To reduce false readings:
1. turn the gain down.
2. have matching transducer to your readout.
3. recognize thermal layers and bio masses.
5. Fish finders should be adjustable for tweaking for the optimum finding of FISH.
Thanks I will try that ..

s/v Mahalo
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post #10 of 18 Old 09-23-2008
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Mine does that a lot also. I'm also guessing it's fish.
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