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Author Topic:   SONAR Transducer Dies After Grounding
thunderpaste posted 12-09-2009 07:57 PM ET (US)   Profile for thunderpaste   Send Email to thunderpaste  
[Moved to SMALL BOAT ELECTRICAL from another dicsussion area.]

I recently purchased and installed the Raymarine A50D on my Montauk. Everything was working fine until one day I ran onto a mud bank. After backing off the mud I got back on plane to avoid further groundings while I navigated though a narrow bayou, which required a bit of concentration.

After about ten minutes I was back in Lake Catherine and I noticed a knocking sound. Upon further investigation I noticed my SONAR transducer had been snapped off the mounting bracket and was bouncing against my hull and engine cowling while I sped along at about 30-nautical miles per hour. I secured the transducer until I got home, and it easily snapped back onto the bracket.

A few times after that the SONAR worked sporadicly and now not at all. I have already purchased another transducer but before going through the install I want to get some feedback from the members here.

Are transducers typically sensitive to the point that the beating it took could break it?

What do you think happened? I think it may have partially messed up the cable connection. That may explain why it worked on and off for a while.

HAPPYJIM posted 12-09-2009 07:59 PM ET (US)     Profile for HAPPYJIM  Send Email to HAPPYJIM     
I'll bet both will have something to do with it not working.
thunderpaste posted 12-09-2009 10:20 PM ET (US)     Profile for thunderpaste  Send Email to thunderpaste     
I'm sure they will too. My ear is forever tuned to the sound of that thing hitting the hull so IF it ever happens again hopefully I will hear it, or better yet remember to check it before going WOT.

I guess what I am asking is has anyone else experienced something like this? I assumed the potted wire connection and transducer itself were designed to take a beating considering the conditions they operate in.

Weird thing is I really didn't run onto anything hard. Only some marsh mud as I took the inside turn of a bayou trying to be courteous to some fishermen. I was able to reverse off on my own power. The transducer was mounted similar to the examples on this site.

jimh posted 12-10-2009 09:11 AM ET (US)     Profile for jimh  Send Email to jimh     
Most likely the transducer element or the electrical cable were damaged by the physical abuse they received from whipping around while the boat was run at high speed.
thunderpaste posted 12-10-2009 09:39 AM ET (US)     Profile for thunderpaste  Send Email to thunderpaste     
Thanks Jim. Just looking for a second opinion before I go through the trouble of reinstalling this weekend.
Nauti Tauk posted 12-10-2009 06:20 PM ET (US)     Profile for Nauti Tauk  Send Email to Nauti Tauk     
Last year while fishing on Lake Lanier I had the misfortune of hitting a floating 1x6x5' dock board. The Lowrance skimmer transducer took a good hit. The unit worked the rest of that trip but upon later inspection on the trailer the unit was cracked along the seam of its upper and lower half. Next time I put the boat in the water the unit wouldn't work at all. I guess the unit has an encapsulated coil of some sort that will stop working if subjected to a substantial impact. (Jim?) I did have to replace the transducer and all was well again. Sooo, yes if the unit bounced around whacking the transom and engine cowl that'd pretty much make it toast.
jimh posted 12-11-2009 08:52 AM ET (US)     Profile for jimh  Send Email to jimh     
I don't know precisely what might be inside your Raymarine unit's SONAR transducer, but I suspect the transducer element itself is likely a piezoelectric crystal or ceramic wafer. Several years ago I was involved in the process of removing a through-hull SONAR transducer from the hull bottom of a boat. The transducer was so well bedded by an adhesive sealant that it became very difficult to remove. An attempt was made to weaken the strength of the transducer assembly by drilling through it. We found we could not drill through the middle of the round transducer assembly and presumed the cause was the hardness of the ceramic piezoelectric element.

A ceramic transducer element itself might be resilient, but the electrical wires in the cable could be damaged from being stretched and yanked from towing the element through the water at high speed.

thunderpaste posted 12-15-2009 08:00 PM ET (US)     Profile for thunderpaste  Send Email to thunderpaste     
New transducer is installed and plotter now recording ping. Will report on field test ASAP.
kwik_wurk posted 12-17-2009 12:26 AM ET (US)     Profile for kwik_wurk  Send Email to kwik_wurk     
Cracked crystal, I would bet good money on that.
thunderpaste posted 12-21-2009 09:11 PM ET (US)     Profile for thunderpaste  Send Email to thunderpaste     
Everything working fine now. The resolution of the A50D is incredible.

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