Can I check a depth gauge when out of the water?

[Bloater]

Does anyone know a 'trick' to get a depth transducer to give out a reading when the boat is out of the water?

Depth transducers as I understand work by using ultrasound. If there is any air on the surface of the transducer it will not work. My boat is out of the water so there is quite a lot of air about.

I really want to verify that it is working properly before I launch the boat, is this possible?

Incidentally it's a Raymarine ST50 (Airmar) type.

 

[Gwylan]

quick & cheap

Does anyone know a 'trick' to get a depth transducer to give out a reading when the boat is out of the water?

Depth transducers as I understand work by using ultrasound. If there is any air on the surface of the transducer it will not work. My boat is out of the water so there is quite a lot of air about.

I really want to verify that it is working properly before I launch the boat, is this possible?

Incidentally it's a Raymarine ST50 (Airmar) type.

Put a bucket of water under the transducer. It should show about 4 times the distance between the transducer and the water surface.
Sound travels x4 in air compared to water. Just a quick and cheap way to check the transducer.
Can even work without the water, depends on the surface below the boat.

Hope this helps

 

[Slycat]

clicks

Some transducers (the NASA one I use with my Target) make a faint clicking sound.

Its a good first test to check the head unit is using the transducer.

I test my transducer by hanging it over the side of the boat into the water so bucket of water as mentioned should work.

 

[doug748]

It is very tricky, to get any open container of water to make contact with the hull.

I finally cracked it by chocking a solar shower bag (any stout flexi container would do, maybe a hot water bottle) in position against the hull.

 

[Twister_Ken]

My experience of the Airmar depth function - it just works. Sometimes water conditions can give strange readings, but the kit is dead simple, nothing much to go wrong unless it's DOA.

If only the speed function was as reliable.

 

[Billjratt]

If the xducer is through hull, you may get an airborne reflection from something hard (reflective!) I got a reading while the boat was on a concrete section of the yard. see http://www.ybw.com/forums/showthread.php?t=298709 for the figures.
You could of course just listen to the xducer, to hear it clicking, or do you need to verify the display as well?.

 

[Bloater]

Hi, thanks for your replies.

The depth sounder worked before I was lifted out and I have no reason to think that it won't work when back in the water. The desire to test the gauge is due to the fact that I have just installed a new chartplotter and it doesn't display the depth reading for some reason. The tridata instrument is flashing '0.00' at the moment (as you might expect) and I think perhaps this is why I'm not getting the correct data displayed on my chartplotter (which says '----'). I was hoping I could trick the depth sounder into giving out some sort of reading so I can check the NMEA link between the sounder and plotter.

 

[VicS]

Hi, thanks for your replies.

The depth sounder worked before I was lifted out and I have no reason to think that it won't work when back in the water. The desire to test the gauge is due to the fact that I have just installed a new chartplotter and it doesn't display the depth reading for some reason. The tridata instrument is flashing '0.00' at the moment (as you might expect) and I think perhaps this is why I'm not getting the correct data displayed on my chartplotter (which says '----'). I was hoping I could trick the depth sounder into giving out some sort of reading so I can check the NMEA link between the sounder and plotter.

Try the hard reflective surface below the transducer. If the sounder then gives a reading you will be able to check the link to the plotter.

 

[Danny]

Does anyone know a 'trick' to get a depth transducer to give out a reading when the boat is out of the water?

Depth transducers as I understand work by using ultrasound. If there is any air on the surface of the transducer it will not work. My boat is out of the water so there is quite a lot of air about.

I really want to verify that it is working properly before I launch the boat, is this possible?

Incidentally it's a Raymarine ST50 (Airmar) type.

Try the method described here. Note the post a few down where a forumite suggests a slightly different depth "multiplier".

 

[Bloater]

Thanks Danny, that sounds like a good tip. I shall certainly try that when I'm next down at the boat.

 

[pvb]

You need a piece of plastic drainpipe about a metre long, with one end closed off. Put the open end of the pipe over the depth transducer, with the pipe perpendicular to the hull. The multiplier is actually 5, so the depth display should read about 5 metres (because the speed of sound in air is about a fifth of the speed in seawater).