Dicky Fish Finder

[whisper]

Sorry to disturb you with a technical question. No, I'm not really, so here it is.

Whilst doing trials on new boat we found that for no apparent reason the depth reading on the fish finder would suddenly jump from a correct reading of say 6m, to 100+m. This happened at low speeds - 5 to 10 knts and could only be cured by turning off the set a few times and then turning it back on. The animal in this instance is a FishEagle 2 which we will use as a clearer depth gauge than the Autohelm Bidata that came with the boat. Unfortunately the latter didn't register any depths at all, though the speed read ok. We have taken this out and sent it back.
The transducer for the FF is fixed in the engine compartment bilge and is a through hull type.
Any suggestions as to what we should try ?

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[byron]

<font color=blue>If the transducer is housed in an oil bath make sure it is full and there's no bubbles. As regards the non working one, check for dry joints and bad connections.

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[whisper]

Thanks, it's not in an oil bath. We've sent the other one back to Raymarine/Autohelm to see if the instrument itself is u.s.
If it isn't then it's back to the drawing board and perhaps try another transducer.

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[omega2]

Try manually altering the gain control, sometimes on auto gain the power is so great that it fires through mud and gives double sometimes even quad readings, switch to manual and set gain to give a false bottom i.e. read 20ft and then under it read a feinter 40ft. Do you have an operators Manual? if not speak to me.

<hr width=100% size=1>J HAMER

 

[omega2]

Further, Did you fit the transducer? if so did you find a solid bit of boat to fire through? some boats are of a sandwich construction and this cannot transmit sonar i.e. there must be no air between the face of transducer and the water you are sounding, hence the fish you see is the air bag.

<hr width=100% size=1>J HAMER

 

[whisper]

Thanks. I'll investigate further later this month.

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