in-hull transducer ?

Gerald A. Gotts · Post by **Gerald A. Gotts** » Mon Aug 11, 2008 12:22 am

I guess I don't understand this term " in-hull " transducer. Can anyone un-confuse me ? It's so much easier to be stupid on a forum than in person. Is there a way to have a transducer work without drilling a hole in my boat ? If so why do it any other way ?

Confused,Jerry

CharlieJ · Post by **CharlieJ** » Mon Aug 11, 2008 9:02 am

An in hull transducer is glued to the inside of the fiberglass hull, and shoots through that hull. Solid glass fiber is transparent ( for all intents) to the RF used for sounders.

The normal adhesion recommended by manufacturers is epoxy. I've called several and asked.

You must make sure there is NO coring where you want to mount the transducer, and also no air bubbles. The simplest way to find this out is to fill a baggie with water, purge the air, lay it in place where you want the transducer and lay the transducer on top. If it reads ok like that, it'll read ok when glued down. Move the baggie around till you find a good spot.

Gerald A. Gotts · Post by **Gerald A. Gotts** » Mon Aug 11, 2008 9:31 am

Charlie, Thank you for the info. I'm not quite ready to do the work yet as there are numerous jobs scheduled for Voyager first. When I get to that job I will surely go with an in-hull transducer.

Rachel · Post by **Rachel** » Mon Aug 11, 2008 12:34 pm

Just a note: When you do go depth- or fish-finder shopping, don't necessarily be discouraged if the one you're looking at does not have this transducer with it. Some manufacturers (I'm thinking of Humminbird specifically) will do a "free" trade where you send them the (other type) of transducer that came with your new unit, and they send you the appropriate one for free (I think you do have to pay shipping). I think this is their solution to the "how do we have stores stock units with every kind of transducer" dilemma.

I last did this about two years ago, so of course it bears current checking.

Rachel

Quetzalsailor · Post by **Quetzalsailor** » Mon Aug 11, 2008 1:47 pm

There are variations: some folks seal their transucer to the inside of the hull with sealants (I would not have thought it appropriate); some epoxy 'em (then what?); some mount theirs in a tub tabbed or glued to the inside of the hull.

Dad did so in the Morgan 27. He fitted a length of pvc pipe to the hull, epoxied it in place, made a lid with a mounting for the transducer. I replaced/topped up the water each season with a smidge of bleach in it. It began to leak after a number of years - epoxy doesn't really stick to PVC - so I'd have to top up once during the summer.

Rachel · Post by **Rachel** » Mon Aug 11, 2008 7:55 pm

Quetzalsailor wrote:There are variations: some folks seal their transducer to the inside of the hull with sealants (I would not have thought it appropriate)

All of the manufacturer's recommendations that I've seen have said to use epoxy, and not a sealant (i.e. caulk, silicone). I believe it's because the density is better.

Quetzalsailor wrote:...some epoxy 'em (then what?)

I'm wondering what you mean by the "then what?" Typically, you then just use the depth/fishfinder.

Quetzalsailor wrote: He fitted a length of pvc pipe to the hull, epoxied it in place, made a lid with a mounting for the transducer...

I've never used this method, but it feels like "the old fashioned way" to me, and I'm guessing that for a simple "puck" transducer it's probably more complicated than necessary - although I'm sure it would work well.

Rachel

Quetzalsailor · Post by **Quetzalsailor** » Tue Aug 12, 2008 8:44 am

Then what? How do you get a failed transducer back out? Bash it to death and grind the remains off? Sounds indelicate!

I have the Datamarine plastic throughhulls and transducers for speed and depth. Two, large, extra holes. (We don't use the speedo, since I'm, like totally, chicken to pull the blank plug out [the paddle wheel would foul in about 2 weeks in our part of the Chesapeake])

A previous owner's transducer was mounted under the galley sink. When we bought the boat, I assumed it was a seawater intake for the galley footpump; it looked like an ordinary throughhull, threaded stem and nut. It was sealed with goo from the top and visible just as a faint circular misshape from below. So, I set about removing it, using my patented scrap wood and threaded rod puller. Tried to drill the sealant out for the rod: no joy; went at it from the bottom and the drill would not penetrate beyond the bottom paint! Turned out that it had a solid, hard ceramic disc potted into a special bronze throughhull. I had to dig the disc out of the potting and then I could drill up through the throughhull for my puller. (I hate bashing on stuff like that, but I don't mind excessive force gently and locally applied.)

CharlieJ · Post by **CharlieJ** » Tue Aug 12, 2008 9:12 am

if the trasnsducer has to come out, just bang it with a hammer on the side. Most of the time it'll just pop off, but if it breaks so what? You're replacing it anyway cause something doesn't work.- grin.

Then flatten the area and put the new one on.

I've used the PVC pipe and suspended transducer. Hard to get a seal to the hull to prevent leaking, but doable. I used mineral oil in mine per recommendations. NOT mineral spirits- mineral OIL, from the drugstore. I drilled and tapped a hole in the top and inserted a machine screw. Used a syringe to squirt the oil in. A VERY good idea is two holes- one for air escape and one to fill through.

Our transducer now is epoxied to the hull though.

We use a Humminbird fishfinder. The only real problem is that it goes nutso in less than 4 feet, so when we need it the most- feeling our way into an anchorage, it's useless. So we resort to the time honored lead line. Me on the bow heaving the lead and my wife driving, ready to bail out when I tell her to do so.

That ALWAYS works.

Rachel · Post by **Rachel** » Tue Aug 12, 2008 9:42 am

Quetzal,

The type of transducer I was referring to is a "puck" type. There's nothing that goes into or through the hull (except for the beam of energy). So it's just a surface mount on the inside of your hull.

Like Charlie says, you can knock it off and then grind smooth and either install a new one, or whatever. The surface area is not that large.

Rachel

Gerald A. Gotts · Post by **Gerald A. Gotts** » Wed Aug 13, 2008 12:21 am

Hey, thanks you guys I really appreciate the help. Boy, am I ever gonna sail this thing? I have to admit though it is fun to work on the boat.

Grog to all

Peter · Post by **Peter** » Wed Aug 13, 2008 11:27 am

FWIW, I glued my Huminbird transducer in with a gob of Sikaflex. I knew I might have to move it later, so I wanted to be able to remove it by non-destructive methods. Anyway, on the Albin Vega Forum several people had done this so I gave it a try, even though I was skeptical. Works like a charm!

Shoalcove · Post by **Shoalcove** » Sun Aug 17, 2008 1:03 pm

I keep mine inside the hull. I stuck a piece of pvc pipe to the hull with 4200 and filled it with mineral oil. For a long time it didn't even have a cap- I just stuck a piece of sponge in over the transducer but this year I added a lovely orange Home Depot cap fitting. 4 years: no leaks - no problems. Raymarine 60 btw (I hope I didn't just jinx myself!)
Now , I just have to get around to knocking out the old one and filling the hole.
Cheers,
David

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in-hull transducer ?

in-hull transducer ?

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