Faulty depth sounder

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robertt

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I finally got my boat delivered to Troon and I am very pleased with her. She is a Trapper 501 with bilge keels.

From the survey and from the delivery skipper's handover I now have a fair list of points to get sorted.

One point is that the depth sounder is faulty. It powers up but constantly reads 3.8M. Can anyone tell me if this is likely to indicate a problem with the instrument display or the transducer? And will it need a lift out to put right? Also the log is inoperative, not quite sure whether he meant it was just reading wrongly or not working at all. Again does that require a lift out?

Thanks for help guys

Robert
 
Shouldn't need a lift-out, as the transducers are designed to be withdrawn from their sockets with the boat afloat. You do need the correct blanking plug to immediately shove in the hole, though - hopefully this will be on board. Done smoothly this should only let half a pint or so of water into the bilge, though I grant you it's a bit unnerving the first time.

Can't help you with the actual fixing.

Pete
 
Some depth sounders are fitted to to the hull and cannot be removed. Others are mounted inside the hull and are removable.
If fitted externally to the hull has it been antifouled over? Some but not all are affected this way.
If it is mounted inside the hull has it been mounted in to an oil bath and the oil bath is now empty?
 
robertt said:
One point is that the depth sounder is faulty. It powers up but constantly reads 3.8M.
Click to expand...

What make/model is the sounder?

If the transducer isn't fouled then it would be worth re-making the power/data connections.

Perhaps if the log is on the same circuit there is a poor power or earth connection at the main distribution board.
 
robertt said:
Thanks. Not sure what an oil bath is. I will try to get a look at the transducer and check connections.
Click to expand...

Those fitted internally are sometimes/often/usually mounted in a tube, glassed to the inside of the hull, filled wth an oil . Castor oil was used by some manufacturers. Mine ( Seafarer) is mounted in a tube of castor oil.
 
I have a NASA and it failed in the end it was the screen. My local chandlery let me take both the transducer and screen on sale and return and I was able to sort out which was at faulty.

Before you do any of these check the oil, you need castor oil and the transducer needs to sit in it, put the oil in firs tand then place the transducer in until it can go no further then lift it up a little. This has worked for me.

Good luck

Delbuoy
 
If the depth transducer is attached to the hull with a blob of silicone; easy removed, checked (with bag of water) and replaced. If you can't remove the sounder, you might be able to get an ear close enough to hear if it's ticking - but a constant reading sounds very much like a working transducer with an air bubble.

Assuming the log is an impeller, it's probably gunked up with, if you're lucky, ascidians, or, if unlucky, barnacles. If you have a cap for the tube you'll let a mug or two of water into the boat the first time you try it, so lift any carpet. If you don't have a cap, then you'll need someone with a cloth (or potato, carrot, whatever) to bung up the hole while you scrape the impeller and check that spinning it does actually register a speed.
 
agurney said:
If the depth transducer is attached to the hull with a blob of silicone; easy removed, checked (with bag of water) and replaced. If you can't remove the sounder, you might be able to get an ear close enough to hear if it's ticking - but a constant reading sounds very much like a working transducer with an air bubble.

Assuming the log is an impeller, it's probably gunked up with, if you're lucky, ascidians, or, if unlucky, barnacles. If you have a cap for the tube you'll let a mug or two of water into the boat the first time you try it, so lift any carpet. If you don't have a cap, then you'll need someone with a cloth (or potato, carrot, whatever) to bung up the hole while you scrape the impeller and check that spinning it does actually register a speed.
Click to expand...

If you can't get your ear near enough - or aren't convinced, find an older portable radio with LW - and tune to about 200KHz. If your instrument is working - you will probably hear a steady repetitive ticking on the radio. If it's a internal NASA depth transducer is is possible for a little air to get under the transducer over time. - top up.

Graeme
 
If you're unhappy taking the transducer out when afloat dry her out and do it in between tides if you can find anywhere suitable, that's the advantage of having bilge keels.
 
pagoda said:
If you can't get your ear near enough - or aren't convinced, find an older portable radio with LW - and tune to about 200KHz. If your instrument is working - you will probably hear a steady repetitive ticking on the radio. If it's a internal NASA depth transducer is is possible for a little air to get under the transducer over time. - top up.

Graeme
Click to expand...

Ha! that reminds me, my depth sounder gives a tick and sometimes carrier on VHF channel 74 (the Crinan canal's working channel .. I used to blame them for not listening when I was based in Bellanoch .. but that's water under the bridge)
 
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