Shoud the depth sounder work when ashore?

[SimonFa]

I've got my boat ashore and when doing some work on the instruments I noticed the depth wasn't registering. I have cleaned the window as there was a bit of anti-foul paint on it but that seemed OK.

I don't want to put her back in the water only to find she needs to come out again.

Thanks,

Simon

 

[Lucky Duck]

Certainly doesn't work ashore on my Raymarine/Airmar set up.

 

[Neil_Y]

They only work in water, even air bubbles can stop them working. Water transmits sound far better than air.

 

[Seajet]

There is a way of getting a reading with the boat ashore but I forget it at the moment, hopefully someone else can remember.

To check a depthsounder is actually working is easy; with it on, listen close to the transducer; there will be a faint ticking at about 60 beats per minute.

Transducer failure is extremely rare, so I'd say you're safe to launch if the transducer is live, making this ticking sound; any problem after that will almost certainly be the head - display unit or the cable anyway, or if the transducer is mounted inside the hull an air bubble between it and the hull can spoil things.

 

[Richard10002]

I think I asked in 2009, and the answer was to put a bucket of water directly under it. I think it might even record the correct depth. The ticking is a good sign aswell.

 

[charles_reed]

Mine does, but inaccurately - Airmar and Navico.

 

[SimonFa]

Thanks for the prompt responses.

I'll use the listening and bucket tricks but I already have peace of mind because it was working when I took her round to be lifted.

Simon

 

[Sandy]

I think I asked in 2009, and the answer was to put a bucket of water directly under it. I think it might even record the correct depth. The ticking is a good sign aswell.

+1

I even get a reading of 0.7 m!

 

[Spirit of Glenans]

Through-hull depth transducers are removable while afloat - aren't they?

 

[Twister_Ken]

Through-hull depth transducers are removable while afloat - aren't they?

Not generally. Speed ones are, because there are moving parts which get clogged up with marine life and need cleaning, but depth ones are just a flat surface on the outside of the hull and I'd have thought a bit of growth on them wouldn't affect the reading critically.

 

[Billjratt]

Ashore it depends on what your transducer is pointing at (same as afloat if you've ever been confused by soft mud...) Anyway, I was most surprised to get a reading when my boat was on a concrete hardstanding. I even worked out the error against the relative propagation figures for air and water -it was correct.
I suggest that you may get a result if you put something flat,hard (like a tile) under the transducer. You're not supposed to put your lug near/against the transducer to test it, so if you're hard of hearing get a tranny radio tuned to the long wave and you'll hear the ticking. Of course the ticking only counts for half the requirements - if it ticks but doesn't register, the receiver or timer is faulty, do swappies with a friend to confirm.

 

[Seajet]

Billjrat,

who says you're not supposed to put an ear close to the transducer, not heard that one ?

 

[Billjratt]

Just read it somewhere a while ago. The ping is pretty powerful and I assume it may damage the inner mechanism of the ear. Or maybe promote tinnitus.

 

[Seajet]

Not with any depthsounder I've ever tried ! maybe putting one's ear actually on the transducer face might be dodgy, but listening near the thing inside the boat it's very quiet indeed.

 

[Avocet]

Ours (NASA) reads in air - just incorrectly.

 

[lpdsn]

The transducer will be designed to efficiently transmit the sound to the water. It won't be matched to air so you'll get an awful lot of sound reflected. Don't know if it'll damaged it, but there'll certainly be more energy coming back than normal, so I would be inclined to avoid risking it.

Lead line will work just as effectively in the yard.

 

[lpdsn]

Not with any depthsounder I've ever tried ! maybe putting one's ear actually on the transducer face might be dodgy, but listening near the thing inside the boat it's very quiet indeed.

Don't they work at something like 200KHz? If you can hear that you must find those ultrasonic dog whistles really irritating.

 

[elton]

Billjrat,

who says you're not supposed to put an ear close to the transducer, not heard that one ?

That's because you've had your ear too close to the transducer.

 

[Seajet]

Thanks, I was waiting for that one from somebody ever since I typed it...

 

[johnphilip]

Through-hull depth transducers are removable while afloat - aren't they?

Most only go downwards as they have a lump on the bottom, some like my old Navman will withdraw like a paddle wheel log.