Transducers

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obb.swb

New member
We have a 19 ft C-Dory and are having trouble with the depth finder transducer.....its always getting banged up since we live on a river and hitting stuff is unavoidable. Does anyone have any experience attaching the transducer to the inside of the hull???
 
You can do a thru hull that fits flush on the bottom of the hull.
Or glass in a regular transducer anywhere you have solid fiberglass to shoot the signal through. Mine is glassed in the at the little sump at the rear of the boat right next to the sump pump and works well.

I remember several threads on the subject, you can search the archives.

Also the Hull Truth forum has had numerous informative threads on this subject over the last few years.
 
Texasair covers this well. Remember that the bottom of the C Dory is cored, and the only place on the 22 is the sump aft (and in some a sump right by the cabin door)) which is solid glass. You can cut out core, and then glass in the edges, and an extra layer or do on the bottom

Setting the transducer in water will allow you to see how it will work in a place. (either just water in the part of the hull to cover the bottom of the depth sounder, or a baggie full of water pressed to the transducer.

After you decide where to put the transducer, then mount it in some media which will transmit the ultrasonic waves: Mineral oil, (I make a box), silicone or epoxy resin are media--but you have to be sure there are no bubbles.

I don't suggest a thru hull flush transducer, because you have to undercut the core, and it a fairly big job to get it all right with out risk to the bottom of the boat. Some other boats, that is the best way to go.

The other question is why are you dinging up the transducer? I boat a lot on rivers, and never have had damage to the transducer. I have it set flush to the bottom of the boat (not below) and set to kick up if it hits something--which is rare.
 
My Garmin transducer is epoxied inside in the small bilge under the sink in my 22. I tested it first in a baggie filled with water to be sure it would work. Garmin was also OK with this installation. I can read temps at a slower rate but we can see them. I have not had any problems with this installation. This is third boat I have had done this way. Easy to do and no hole thru the hull.
Pete
 
On both my 19 and 22 I epoxied wih marintex just ahead of the helm bulkhead under the berth where the core transitions to single skin. I put it as close to center line as possible. Has been trouble free, no holes, no penetrations no worries. Reads well up to 20 knots most days. Also reads water temp by hull temp. We know not to go in when it says 54f like this morning.
 
Pete,
Is this in the sump which is under the step at the aft bulkhead, or at the outer turn of the bilge under the galley. I am having problems visualizing a sump under the sink. It is possible that the slight reverse chine at the outer part of the bottom is solid, and not cored. I have never tested this with ultrasound. A dry balsa cored hull will not transmit the ultrasound signal. A wet core might.

George is absolutely correct, that the hull transits from cored to solid just in front of the helm bulkhead. I had wondered if this area might have intermittent contact with the water as the boat worked thru seas at planing seas.
 
Hi Bob. I do lose signal depending on trim and speed. At wot and 24 knots I lose signal often. Since I rarely run that speed it's not an issue for me. At my usual speeds of 6-12 knots I always have bottom.
 
Speaking of transducers, I have a Garmin GPSMAP 541s, and it usally has a hard time finding the depth initially, particularly in shallow water. However, as the water gets deeper, it usually starts reading, and then will read down to about 3 feet or so, before losing the depth again. I have the unit set to auto, which switches between 200 and 50 hz. Are there any depth sounders out there that work well in shallow water? Or suggestions for getting the GPSMAP 541s to find and maintain the reading better? Colby (P.s., I have my transducer mounted on the stern, and works well there....when it works....)
 
For shoal water, set the depth on manual, go to the lowest range as I recollect it is 0 to 10 feet, but may be 0 to 5--I have several different sounders on my boats.

Then drop the gain until you pick up the bottom. Often there is too nigh a gain, which is the problem in very shallow water.

With the 441s, I can read 1 feet in sand as go in and out of the bayou in winter lows.
 
Well, I have tried putting my GPSMAP 541s in manual and the rest of the suggestions, however, it still doesn't seem to find the bottom very fast. It's almost like it's searching for quite some time. But once it gets it, I've had it read as low as 1.5 or 2, before finally giving up the ghost. Then it doesn't seem to want to work until I get in deeper water again. Any more suggestions? Any suggestions on stand alone depth sounders that work well in shallow water? Thanks. Colby
 
Yes. The Transducer is just about flush with the bottom of the boat. Today, I had it reading accurately down to around 1.7 feet before it started flashing and losing the readout. Picked it up again around 7 feet. Not sure if it matters, but the bottom I'm over is mostly mud (muck) or sand.
 
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