Transducer reports depth infrequently

[Bill.Secure]

My Garmin 498 is reporting the depth infrequently. How often seems to be a function of a)how much fuel I have (the less fuel the better it works), b) how fast I am going, and c) the approximate depth of the water. I strongly suspect the problem is cavitation due to incorrect installation of the transducer

I've had one trip back to the dealer on this (and some other matters). They looked at it and said they could see nothing wrong and suggested I call Garmin. The Garmin manual shows a diagram with the transducer about parallel to the hull and states the transducer should be about an eighth of an inch below the hull. The boat is in the water now but my recollection is that the transducer has a very discernable downward angle (the aft end it being lower than the front end). I tried to reaffirm this by feel but wasn't able to. I may give it another try from my dinghy.

I'm looking for c-brat thoughts on this one. Is my theory of cavitation a reasonable one or have I just been inhaling too much oak pollen? Is there a methodology I need to lay out to the dealer for correctly modifying the placement of the transducer if indeed that is the problem? I'm trying to avoid multiple trips back to the dealer.

As always, I appreciate all thoughts and ideas.

Bill
Edgewater, MD

[mikeporterinmd]

"the aft end it being lower than the front end"...that would seem to me to
be quite wrong. Mine is lower on the transom than it should be, but it
works fine, so I haven't messed with it. Its center line is parallel to the
bottom. Lowrance, but it probably does not matter.

Mike

[Papillon]

I don't think your transducer is installed wrong, and 1/8" isn't going to cause the problem you are describing. If your dealer thought it was a problem with the location of the transducer he would have changed it, since it is a easy fix.

I would suspect the setup or adjustments may need to be tweaked a little. I would suggest you get the boat out of the water and take a few pictures of your transducer setup and see if you have anything in front of the transducer such as a water intake causing some uneven water. You might also look to it's relationship with trim tabs...??. Check the cable connections to the helm unit.

Now if it isn't acting any better by now, it is time to get on the phone to Garmin and talk to Tech. Support. By process of elimination you will have enough information gathered to allow the tech to deal with the remaining possibilities.

[Hunkydory]

[thataway]

I agree that a slightly foreward angle is the best installation. I prefer to install the transducer on a piece of "King Strarboard" which is screwed/sealed to the hull, and you can reposition the transducer without chaging the hull screws (sealing and keeping water out of the transom)

You may want to have the transducer slightly more down--1/4 to 3/8" if you are having problems. My two boats keep locked on the bottom up to over 40 knots (TC and Century--just puttin in new FF in the CD 25)

Generally the C Dory are easy, since the bottom is relitatively flat, no strakes. Be sure that the transducer is on the right side (left has prop cavitation wash to cause turbulant water).

[Sarge]

Bill,

You mentioned depth and speed as being some of the issues. I find that mine, a Raymarine, shows no exact depth if I am moving faster than a crawl when depths are over 200'. It was explained to me that the 'ping' has to travel too far and it can't keep up with the speed of the boat. When the signal bounces up from the sea floor the boat has already moved too far away for it to read the signal clearly. Let me also quickly state that my 'sonar' is attached to my Raymarine E80 and on the right hand side of the screen is a scale that always lets me know the approximate depth of the water. So I may not have the exact depth of the water, but I know if I am in 200' or 600' or more of water (I confirm this with what is listed on the GPS/chart).

Is your issue similar or did I 'miss the boat'?

Good luck,

-Sarge/Carl

[Papillon]

[Bill.Secure]

Lesser depths are certainly at the top of my concern list although I want the unit to perform correctly in all of its modes.

What is significantly concerning me is having the dealer perform the warranty work and being done with it in a single visit. From the discussion I had with them last time, I'll be taking the boat up the Bay to East Baltimore and then prove to them on the water it isn't working. Then they'll have to lift it out and make whatever changes seem required, then put it back in to prove its working correctly.

I also don't want a transom that looks like a pincushion from filled screw holes, so I'll attempt to get them to use the methodology cited by Bob in an earlier post although I'm pessimistic about getting them to do so.

[Moxieabs]

My depth sounder was giving irratic and erroneous readings mixed with reliable ones for about seven days before the transducer totally died. Might have a different transducer substituted for the paresent one.
Dave

[Alok]

I have a Raymarine C-80 integrated system. The boat is kept in the water full-time.

The depth sounder worked great for the first 2-3 months, then started losing the bottom at any speed over 6-7 mph. The reading would come back when the boat slowed down.

When the boat was hauled for engine service, I found that the transducer was covered with barnacles. I cleaned these off, and it worked fine for another couple of months. However, last trip out, it again began to intermittently misbehave above 7 mph.

For those boating in our warmer Southern waters- is "barnacle induced malfunction" a known problem? Are the barnacles casuing enough turbulence in the water flow around the transducer to make it malfunction? If so, is there any kind of anti-fouling paint I can safely apply to the plastic cover on the transducer?

Or are the barnacles just a red herring (!) and am I facing a gradual transducer failure?

[Sarge]

Alok,

That's a great question. My boat is in the water all the time too and right now I'm having the bottom painted. Can the transducer be painted? Should it be painted?

Geez, just goes to show that you don't know what you don't know. Never even thought of barnacles on the transducer.

-Sarge/Carl

[Wefings]

http://www.boatersworld.com/product/376620019.htm
A light scrubbing with a soft brush once in a while[ if practical ] is good too . A transducer is like a speaker/microphone. Barnacles or algae are like putting sock over it . You might try dropping in down a little . I prefer a level to the waterline installation .
Marc

[thataway]

There are anti fouling paints specifically made for depth sounder transducers--I have used them and put a single light coat of anti fouling paint on the transducer.

Definately keep the barnicals off the transducer.

[Papillon]

The transducer paint that Marc posted above works very well. But let me point out to those who might decide to add a coat of antifouling paint to their transducers while doing the bottom of their boats....DON'T DO IT because of the copper in some of the paints acts like a shield and can cause your transducer to go "KAPOWL"...

I just got back from my first visit to Bass Pro Shoppes....I now have a nice long Christmas List and I will be posting it here for all my good friends to help them in their holiday shopping...yep that's me...always trying to make my C-Brat friends live a little essayer ...

[Alok]

Marc:

Thanks!

Will definitely try the paint and report back