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Catalina/Capri 25/250 Sailor's Forums

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Transducer Install

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mrapkins
Navigator

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USA
124 Posts

Initially Posted - 06/11/2014 : 08:03:39

Upon launch in April, my P72 transdcucer connected to my Garmin 440sx GPS appeared to start to malfunction - the depth kept flashing and eventually there was no depth displayed at all. When I disconnected the transducer the GPS reported that the transducer had been disconnected so I was fairly confident that the problem with was with the transducer and I discarded it. The transducer was installed using the wax toilet ring method - I broke off a a piece of wax, smooshed the transducer and wax to the hull and hey presto - solid depth readings. This installation was performed about 5 years ago.

I purchased a new P72 and last weekend I spent 5 hours with 2 different wax toilet rings trying to get a reading on the GPS all to no avail.

I tried the original location and several others, I even tried making a wax ring on the hull and melting the wax into to it to ensure no air bubbles and still no success.

If I hang the transducer over the side it works just fine.

If I disconnect the transducer, the GPS reports that the transducer has been disconnected. (Which leads me to believe that the original was working just fine!!!)

If I fill a wax ring (made on the hull) with water I sometimes (but not always) get a reading.

What am I missing???

Have the EPA mandated a change to the make-up of wax toilet rings to make them more eco friendly and, in so doing, rendered them useless for use in transducer installations?

Edited by - mrapkins on 06/11/2014 08:12:19

dmpilc
Master Marine Consultant

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4593 Posts

Response Posted - 06/11/2014 : 09:26:22

Since it works okay hanging over the side, you know the transducer is functioning. I would try one more time to very carefully make a wax patty insuring no bubbles. Lightly press the transducer into the patty insuring no air pocket forms. Hang both over the side to check if the transducer is working attached to the wax. If it is, bring back in, dab off any water droplets, and press against the hull in the original spot. Hopefully, it will still transmit.

Edited by - on

OLarryR
Master Marine Consultant

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USA
3442 Posts

Response Posted - 06/11/2014 : 09:31:13

The one thing that thows a monkey wrench in determining the root cause of your issues getting a good signal is when you indicated you tried filling the wax ring with water and then still did not get a 100% positive signal since you indicated you sometimes but not always get a good reading. My understanding of what you tried in this instance is that you only used the wax ring to form a container sort of to hold the water and that nothing was in between the water and the transducer in contact with the inside of the hull. Yet, when you tried the transducer over the side directly in the water, then the signal was fine. This to me does not 100% indicate the problem is with the wax ring but has to do with a weak or inconsistent signal when used as an in-hull transducer.

I recall the instructions for my depthfinder indicated that it was supplied with a transducer that could be used in-hull or over the transom but when used in-hull, the signal strength would be reduced which they indicated meant it would read fine but only to a depth of 400' vs 1000'. So, in-hull use does effect the strength of the signal. What else can effect the strength of the signal - If too much medium (ie. wax ring matl) is used between the hull and the transducer, that could also effect the strength of the signal.

What else: I recall one season after the bottom had a new anti-fouling paint applied, I initially did not get a consistent signal, it vacillated dockside reading all sorts of depths and error readings. A day later, however, it then read flawlessly from then on. The cause of the erratic readings was the boat was just put into the water and a massive number of bubbles clung to the underside of the new anti-fouling paint. A day later, the bubbles dissippated.

In you case, perhaps it is not bubles but if you have had successive bottom paint layers applied over the old paint, perhaps your signal is a bit weaker getting thorugh all the layers.

Is the transducer designated for in-hull use ? Some are and some are not which may not mean you cannot use it for in-hull but this may vary from mfr to mfr. last thing is and probably doubtful is something wrong with your Garmin unit that requires a stronger signal...but that does not explain why it worked fine all those years and works fine with transducer over the side.

Is it possible that the signal is weaker this year because of perhaps an excessive number of bottom paint layers ?

Anyway, I really doubt it has anything to do with the wax ring. It is apparent from you just using water and trying to get a consistent signal in-hull, that something is amiss. Rcmd instead of water use mineral oil as the medium between the hull and the transducer. if you still do not get a consistent reading, then it is because you have a weakened transmitting transducer signal caused by the bottom paint layers, in-hull location, faulty or incorrect transducer for in-hull application or maybe the specs changed on the the voltage/current required to power the transducer vs what your garmin is putting out.

Anyone have addl thoughts ??

Edited by - OLarryR on 06/11/2014 09:35:41

islander
Master Marine Consultant

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USA
4018 Posts

Response Posted - 06/11/2014 : 11:26:01

Along with Larry's suggestions are you at a dock? Testing in low(under 8ft of water) or murky water? I sometimes don't get a reading in my slip at low tide until I pull out into deeper water. Also check all of the connections for any corrosion that could be causing a low voltage situation.

Edited by - islander on 06/11/2014 11:42:05

delliottg
Former Mainsheet C250 Tech Editor

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USA
4479 Posts

Response Posted - 06/11/2014 : 13:51:47

This may or may not be helpful, but when my transducer died, I dug out my new-old-stock Humminbird, made a 4" PVC ring to fit the inside of the hull in the bow and hot-melt glued it into place (this didn't actually work out very well over time, so I'd rethink this particular aspect). Then I packed it with a wax toilet ring, then took my heat gun to it to melt the wax into a solid mass inside the PVC. Waited for it to start to gel again, and smooshed the transducer into the soft wax. That worked for most of the season, but the hot melt glue failed and the whole thing got dislodged so I need to start over this season. I'm thinking about moving the transducer behind the keel in the aft berth storage locker. That'll relieve the problem of my too-short of a cable.

Edited by - on

Chief RA
Chief Technical Advisor

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USA
191 Posts

Response Posted - 06/11/2014 : 14:33:12

If you guys want to use a plastic pipe ring container I suggest that you silicone it to the hull. After it sets up you can now use the molten wax but as stated, do be careful that there are no bubbles or that your trying to shoot throught too much wax. If you use water it must be in a ziploc bag so you can apply downward pressure on it and once again you need the transducer near the hull with little water in between. Last, I silicone the transducer as near the hull without touching it in the silicone. If it does not read as well as expected quickly remove the transducer and soft silicone and try a new spot until you are happy! I think the reason the companys do not like the in hull installs is many are poor installs and then reflect poorly on their product. I have never put a hole in any of my boats for Sonar and all have worked exceptional! My Lowrance will even show the Dunginess crab on the bottom!
Smart sailors here, sust trying to clarify. Chief,EE(radar,sonar,comm)

Edited by - on

islander
Master Marine Consultant

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4018 Posts

Response Posted - 06/11/2014 : 15:49:55

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"> My Lowrance will even show the Dunginess crab on the bottom! <hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">
Yea but will it show you if its male or female?

Edited by - on

Chief RA
Chief Technical Advisor

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USA
191 Posts

Response Posted - 06/11/2014 : 16:47:01

Man, Scott! I was impressed that I could even see 'em, much less their sexual preferences! Now if you tell me that on the East coast you are seeing Dunginess, we really have a problem!('

') Chief

Edited by - Chief RA on 06/11/2014 16:53:04

Voyager
Master Marine Consultant

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5353 Posts

Response Posted - 06/15/2014 : 09:21:56

Is the face of the unit flush, or is there a lip around the business end? If flush, it should make good contact with the wax, but if there's the slightest ridge around the edge of the face, that could trap some air where you don't want it.

EDIT: I looked at the transducer online, it's smooth - it soes not appear to have an edge. Wonder about the flex in the cable - could that cause one side of the transducer to pull out of the wax slightly?
What does the surface of the inside of the hull look like?
Is it crusty, chipping or is it smooth, solid glass/resin? Maybe wire brush the surfaces?

Edited by - Voyager on 06/15/2014 09:32:02

Chief RA
Chief Technical Advisor

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USA
191 Posts

Response Posted - 06/15/2014 : 18:36:56

Yes Bruce, the air bubbles are a potential serious problem. Even sanding the rough glass surface would seem appropriate before bonding. I use silicone to bond once I find the best spot. Chief

Edited by - on

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