In-hull transducer

Metabarca

Metabarca

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I'm fitting a Nasa echo-sounder to my boat and already have a tube that is handily fixed to the hull in which to place it. However, the tube has a diameter of about 1 cm more than the transducer. I assume this is correct but wanted to check. Moreover, any ideas as to what oil to use?
Thanks

<hr width=100% size=1><A target="_blank" HREF=http://www.comoy.com/saillinks.html>http://www.comoy.com/saillinks.html</A>
 
Caster oil

Get some caster oil from your local chemist. The manufacturers specify this type of oil and I have used it with no problems.

Make sure you keep the bottle as still as possible and let it stand for 24 hours before use to let any air bubbles surface. Pour it in very slowly and let it stand - again to get rid of any bubbles. Pour some in a separate container and "dip" the end of the transducer in it (to wet it) before inserting into the tube.

Remember, the key to successful oil-bath transducers is the eilimination of any air bubbles.

Cheers,

Jerry

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Diameter

Nasa Clipper depth, tube glassed in, filled with castor oil(as mentioned)

Works like a treat, but make a job out of setting up the eccho sounder correctly (re damping and averaging of results), otherwise measurements go bouncing up and down.

In my boat, the tube is *exactly* the same size as the sensor, with maybe a mm to spare, to allow the oil to flow. If you have a cm to spare, what's there to prevent the sensor from falling sideways, and giving a wrong reading ?

<hr width=100% size=1>Group of people on the pontoon: skipper is the one with the toolbox.
http://sirocco31.tripod.com
 
The oil has to provide a good acoustic coupling between the transducer and the hull, which in turn is coupled to the water column. Castor oil is ok but a mixture of 17 parts baby oil and 1 part good quality perfume works best, with the bonus that it keeps your bilges sweet.

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G'day Lucian,

The tube is wider than the transducer so that it can swing and remain perpendicular when the boat heels, this provides a much more accurate depth reading and reduces errors.

When fitting it should be suspended so it can swing freely from side to side, your transducer should have a 'D' link on top, so you need to pass a rod thru' this, the oil will provide the required dampening.

I would suggest you put some oil in the tube for a couple of days to check it has no leaks, no sense in getting everything covered in oil then having the repair job to do.

Hope this helps

Avagoodweekend. Old Salt Oz /forums/images/icons/cool.gif

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