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[Solved] Troublesome Depth Sounder


Admin Bill
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The transom-mounted transducer for the depth sounder which was professionally installed by the original owner was apparently mounted too high and sits above the waterline when the boat is unoccupied or there is little or no weight aft.  I am assuming that is the cause of the erratic behavior.  If the boat squats a bit (as with me at the helm) the transducer apparently gets wet and then works as it should.  It looks like the installer assumed the top edge of the bottom paint matched the waterline.  Nope.

Bummer.

 

I've also read warnings that transom-mounted transducers should not be used with inboard engines.  Hmmmm.

We'll see what can be done over the winter.

Bill

This topic was modified 3 years ago 3 times by Admin Bill

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DC Marine
(@dc-marine)
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Just like real estate, location, location, location. If it isn’t in the water it will not function correctly. It must maintain contact with the water. You have the problem solved.

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Admin Bill
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Here's the problem.  "Professional installation."

transducer
This post was modified 3 years ago by Admin Bill

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Admin Bill
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Posted by: Admin Bil

Here's the problem.  "Professional installation."

transducer

Remedial strategy?

Remove the transom-mounted transducer completely and install one inside the hull (maybe a Garmin GT15M-IH) instead?  Remove the old one, repair the damage and install the new one inside?  Access should be easy.
 
I don't know why the "professional installer" didn't do this the first time around.  The IH transducer does cost more, but installation is much easier. 
 
Bill

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Admin Bill
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More knowledge....

We can add sufficient weight aft to wet the transducer, but it only functions properly when the boat is at rest.  Underway, no joy.

That tells me the installation of the transducer in the shadow of the transom is as much of a killer mistake as mounting it above the waterline.

We've made arrangements to fix all this when the boat is pulled this fall.

Bill


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Admin Bill
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Parts assembled for the off-season repair:

Garmin Airmar P79 Transducer 010-10327-20

Garmin's 8/4 pin adapter cable 010-12719-00

I'm hoping to salvage the Garmin EchoMAP 44dv chartplotter


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Grant
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What is the idea of having a depth finder?   If it's to detect shallows,  you'd want it near the bow,  I'd think.   


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Admin Bill
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Hmmm.  The transducer comes with a fairly lengthy cable.  I'll look around for available space a bit more forward.

Bill


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Rob
 Rob
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@administrator Bill, this is an old thread, so my apologies if I'm reviving it for no reason. 

I noticed that you mentioned moving the transducer inside the hull.  I recently contacted Duffy to find out if the hull on my M160 is constructed of solid fiberglass or is fiberglass over wood (known as "core" construction).  It was confirmed by the factory that Duffy boats are cored.  The in-hull transducer will not work with a cored hull.  So, the options are a thru-hull or transom installation.  

I don't want to drill a hole in my hull for a thru-hull installation, and I'm concerned that the transom installation won't work well, as you have found.

So, what did you end of doing with yours?

Thanks!


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Admin Bill
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@robhouston

I don't know if my hull is cored or not.  My transducer inside the hull works properly when the boat is at rest.  When moving, the signal is lost.

I have found no solution.

Bill


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Rob
 Rob
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@administrator  Bill, I assume you've moved the transducer around to various places within the hull?  It almost sounds like water disturbance is affecting the signal when the boat is in motion.  If that is the case, you might be able to find a better spot within the hull that has less water disturbance.  The fact that it works when the boat is not in motion is somewhat of a good sign, at least that's my understanding.

Thanks for the response, and good luck!

Rob

 


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Admin Bill
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@robhouston

Hi, Rob:

I didn't have a lot of choices to get directly to the hull.  The boat was built with the additional batteries on either side, and I think that area is lined anyway.  The transducer is located pretty much under the helm seat now, and as I mentioned, that doesn't work either when the boat is underway.

 

Bill


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Rob
 Rob
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@administrator Okay, Bill, that makes sense.  It's a shame it won't work when the boat is underway.  

In any event, enjoy the Duffy!

Rob


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