B & G echo sounder

[waterboy]

The sounder on my Ben normally works fine though occasionally the depth reading climbs (or does it drop?) to zero even though there is, or should be, plenty of water under the keel. The reading stays at zero for a few seconds then falls away again to the expected depth. It can be quite excciting.
Thermoclines, fish underneath, submarines etc any ideas?

<hr width=100% size=1>I never make the same mistake twice. I always make new ones.

 

[Moose]

It will normally do this if you are following somebody close behind because of the bubbles in the water. Mine goes crazy everytime I go past a beacon with a weatherstation on it, I presume this is due to the underwater cables supplying it.

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[Georgio]

this will quite often be the result of mud/debris being kicked up from the bottom and giving false readings after a ferry or similar has passed by . once the water has cleared or you have moved on the reading becomes normall again. I experience this all the time.

hope this helps.

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[rhc21]

Had the same problems when following the Lymington ferry in the river with the B&G. We now have an Autohelm ST50 tri and this does not have the same problems, the reading is always steady.

Richard.

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[malcp]

I think most echo sounders will suffer from this to a greater or lesser extent. As has been said you get false echos off bubbles in the water, "knuckles" (vortices) in the water caused by turbulence (other people's prop wash, tidal swirls around underwater features etc). If you read Tom Clancy books it mentions submarines creating vortices in an attempt to escape sonar equiped homing torpedoes!

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[Anthony]

My B&G network depth does exactly the same thing, worried the hell out of me the first time, then I found a line in the manual that says it will happen when going over wash etc. Funny thing is when it has this false reading, it still says that i has a high quality signal!

Anthony

<hr width=100% size=1>The difference between men and boys, is just the price of their toys...

 

[beancounter]

Rapid changes in depth? Certainly the abrupt changes in the sea bottom in the Ionian caused the instrument on our flotilla boat to go a bit loopy.

<hr width=100% size=1>Fabricati Diem

 

[waterboy]

Thanks for the input guys but the first time I noticed this was on passage between St Vaast and Carantin in the deep water channel off Utah beach. I was not following anything, nor were there any boats in sight. The C-Map plotter chart did show a cable in the vicinity but not where I was at the time. On the return trip, I followed my outbound track exactly to see if the same thing happened. There was no anomily this time. It has happened recently again off the Hamble river close to the floating cardinal, south oif the river entrance poles, but again, no boats close by or any fast moving traffic. Ponder on please.

<hr width=100% size=1>I never make the same mistake twice. I always make new ones.

 

[StugeronSteve]

No idea, I too have experienced an alarming loss of depth entering the Lymington River, particularly after the ferry has passed by, but never in "deep water".

<hr width=100% size=1>God only made so many perfect heads. The rest got covered in hair.

 

[rhc21]

As you suggested 'fish'?

Richard.

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[mirabriani]

see p b o a few months back. The auther thought it may have been a submarine beneath him. Scary huh
Briani

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[mirabriani]

see p b o a few months back. The auther thought it may have been a submarine beneath him. Scary huh
Briani

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