Transducer 'testing' on land....

[tanimola]

What is the best way of testing the operation of my, new to me, depth sounder before I put the boat on the water next year???

I know the head unit is operational, it's the transducer that 'worries' me!

Not 100% certain how to connect the transducer to the hull, can I buy a 'kit'?

Any advice would be welcome - thanks in advance

 

[sarabande]

2 issues then.


1. To check the transducer is working you need a power supply, the meter head, transducer, and a chunk of water; pond, river, harbour, etc. Connect everything up together (got the instructions ?) and lower away into the water. You may need to run a Setup program, depending on the make and model.


2. Hull fixing kit is normally specific to a maker, and is usually a

a) thru-hull piece (tube plus an external fairing) which needs a hole drilling through the hull, before you fix it to the hull with either thro'-bolts or dreaded Sikaflex

b) fixing nut to pull the tube tight.


Choosing the right place is important, but the literature will advise you. Normally in clear water, not behind a bilge keel, and at a fairly vertical angle.

If you have a flat area of hull for the hole, you won't need fairing pieces.


Some transducers will work if they are fixed to the inside of the hull, but they need to be given a decent contact medium such as polyethylene glycol to allow the 'ping' to go through the hull an back.

It would be helpful if you could post the make and model.

 

[earlybird]

With the system switched on, It is usually possible to feel the transducer operating by applying very light finger-tip pressure to the face of the transducer.
This provide some indication that the system is functional but it is not 100% confirmation.
The "clicks" might also be heard on a nearby radio, esp. on LW.

 

[Ubergeekian]

What is the best way of testing the operation of my, new to me, depth sounder before I put the boat on the water next year???

I am sitting on the Jouster (no reasonable offer refused) having not fifteen minutes ago got the echo sounder working again. I had a spare transducer, so I just dangled it over the side and plugged into the back of the whirly box - it's an old Seafarer. That solved the problem, so I could then stick the transducer in the oily tube, feed the wire through, tidy up and make good. Job's a good 'un.

 

[electrosys]

You can test a transducer without leaving the comfort of your home.

Simply bung up one end of a length of plastic drainpipe, fill with water and lean it against something solid - it isn't essential to be absolutely vertical, but the more vertical the better. Then suspend the transducer just below the top of the water.

The echoes will not be very clean, as there'll be many reflections bouncing around inside the pipe - but it'll be good enough to tell you whether the transducer is working or not.

 

[pvb]

You can test the transducer by using a length of plastic drainpipe, but there's no need to fill it with water, it works in air too. The end opposite the transducer needs to be capped. The reading you get should be about 4 times the length of the pipe (so a 1 metre pipe should give a depth reading of about 4 metres).

 

[tanimola]

I am sitting on the Jouster (no reasonable offer refused) having not fifteen minutes ago got the echo sounder working again. I had a spare transducer, so I just dangled it over the side and plugged into the back of the whirly box - it's an old Seafarer. That solved the problem, so I could then stick the transducer in the oily tube, feed the wire through, tidy up and make good. Job's a good 'un.

It's the 'oily tube' bit that I'm struggling with...
Do I need to secure in the tube? What do I fill the tube with?
There is a tube already secured to the hull with no fittings, just looks like the transducer sits inside it.
The model is an old seafarer, cannot locate a model or serial number!

 

[Davy_S]

It is very simple, switch the sounder on, place a wet hand underneath the hull where the sounder transducer is, you should feel a pulsating transducer on your wet hand, if you cant, it aint working!

 

[Seajet]

You're on the right lines.

There is NO need for a whole in the hull if you have a grp or wooden boat, and it sounds like she's set up for an internally mounted transducer; confusingly this is sometimes called 'through-hull' but that refers to the signal not theactual transducer.

A little absolute depth range will be lost by the signal going through the hull material, but nothing which is relevant.

The transducer is normally held by the cap on the oily tube, the spigot on the transducer goes through a hole in the cap, then the locking nut tightened against it.

It needs to be secure but obviously not over-tight as it's just plastic.

The oil to use is castor oil.

The whole lot needs to be sealed as well as possible, and that's the difficult bit. No matter what cleaning and degreasing, it's difficult to get a good seal, but the only crucial thing is to have oil between transducer face and hull, so as long as it's over the top of the transducer disc you should be in business.

BTW You can hear a transducer if you get close to it in a quiet environment, making a steady ticking noise.

Have fun !

 

[vyv_cox]

If you have the tube already attached to the boat the first thing to do is to check whether it leaks. Put a couple of inches of castor oil into it and wait a week or so. If no leaks are evident, put the transducer into it. Job done.

Although a closed lid might be a nice addition the transducer will work perfectly well if it is just sitting in the tube, so long as it is coupled to the hull and seawater by a liquid.

 

[Leighb]

There is NO need for a whole in the hull if you have a grp or wooden boat, and it sounds like she's set up for an internally mounted transducer; confusingly this is sometimes called 'through-hull' but that refers to the signal not the actual transducer.

I feel that wooden hulls are not transparent to ultrasound. Unless totally waterlogged perhaps?

Certainly true that GRP hulls can have transducer fitted internally, if properly set up, but I have to disagree about wood.

 

[yoda]

As has been said the whole setup can be tested at home by wiring up to a 12v supply (car battery?) and putting the transducer into water. I found a bucket enough but a water but or filled drain pipe may be better.

On the boat you just need to find a way of securing the transducer into the tube. Mine is secured to the bottom with silicone and then filled with sea water. Just depends on the transducer as to how you do it. A wooden crosshead located in a step in the tube has been very successful for me keeping the transducer located central in the tube. I have never used castor oil only ever sea water which is plentiful and free!

Yoda

 

[tanimola]

Just wanted to thank you all - great advice. Will get onto it this week. Just need to find some castor oil !!!

 

[yoda]

Don't bother = water will do!

 

[pvb]

I feel that wooden hulls are not transparent to ultrasound. Unless totally waterlogged perhaps?

Certainly true that GRP hulls can have transducer fitted internally, if properly set up, but I have to disagree about wood.

Yes, I think I'd also disagree with Seajet's advice. Wooden hulls really need an external transducer.

 

[Seajet]

Well you would, pvb.

Seemed to work fine on the wooden boat I was on once, though I'd stress that was ( non - sodden ) plywood, not thick planked.

Boots sell castor oil; it's the traditional medium used for this purpose and here's a clue, it won't slosh straight out of the tube if the lid isn't 100% sealed...

 

[VicS]

You might be interested in the instructions for internally mounting one of the old Seafarer transducers
See

http://s50.photobucket.com/albums/f337/Vic43/Seafarer 3/

Any liquid will do but it should not be volatile, smelly, likely to degrade., corrosive, injurious to the transducer the GRP or the mounting tube. Freezing would be undesirable too

Water freezes and is sufficiently volatile that it will need topping up now and then ...most likely when you need to use the echosounder.

 

[Gwylan]

Power up the system and let it run in air - just point it at the ground. The readout should be about 1/4 the distance the head is from the ground! Sound travels about 4 times as fast in air as it does in water - for the purposes of this exercise.

Oh and if you're not too old and infirm you may be able to hear the unit clicking - or so I'm told.
Or did someone already suggest that?

 

[pvb]

Power up the system and let it run in air - just point it at the ground. The readout should be about 1/4 the distance the head is from the ground! Sound travels about 4 times as fast in air as it does in water - for the purposes of this exercise.

Wrong way round! Sound travels about 4 times faster in water so, as I posted earlier, the reading will be about 4 times the distance in air.

 

[electrosys]

Although I've never tried it, I can't see how the transducer will work in air - it works by transmitting high frequency sound through a non-compressible medium such as oil or water - even a few air bubbles trapped underneath a transducer glued in situ is enough to screw with the signal.