Depth Transducer

[Gezzer]

I've got a problem with my depth instrument (Silva) the transducer is fitted inside the hull. in an oil bath, it worked fine all last year and was very accurate, however on switching on this year the depth cannot be determined, it gives the overdepth readout when sat in the Marina (4 mtrs).

I have checked the transducer is functioning by hanging it over the side and it instantly gives an accurate reading, but back in the hull no go.

I have reseated it in it's housing, changed it's oil bath, and changed the oil bath to water all to no effect.

The boat did not leave the water this winter, could a layer of slime be enough to prevent it's function.

Any suggestions



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[halcyon]

Could be, the transducer vibrates the hull to transmit signal, and picks up return pulse on hull. If you have a layer of weed or slime it could be acting as a damper.

Only one way to find out !


Brian

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[anabel]

Years ago when using antifouling we always left the spot where the transducer was clear of antifouling. However with modern antifoulings this no longer necessary. Have you a gain control on your echo sounder? If so turn the gain down. If not, the gain may be too high for the shallow depth of water at your berth. Is the reading double what it should be? If so you are picking up the second echo. ( signal hitting the bottom, returning to the hull, bouncing back down again, and you picking up the second echo as it returns. Try moving boat out into deeper water & see what happens.

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[Saltyseadog]

Hi Gezzer

Can you tell me the oil that you used in the oil bath, we have found that you can only use caster oil, which we find hard to obtain from a chemist.

saltyseadog

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[mike_kolling]

I have heard that Petroleum Jelly works quite well

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[Gezzer]

I used ordinary vegetable / cooking oil last year and it worked just fine, some manufacturers state that the transducer should sit in a solution of fresh water and detergent, due to the calibration of the instrument.
But using plain old oil as above worked just fine and the instrument was as accurate as these things are.

Since my first post on this subject I have moved the transducer to a previous in hull location and it now works, I can therefore only guess that there is something preventing it's operation in the original area, I'll check it out when I scrub down later in the year.






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