So what about thru the hull transducer mounting? - The Hull Truth

Recoil Rob · 08-12-2004, 11:12 PM

Will it work well in my situation?

I have an older Lowrance X65. They say in the instructions that the transducer can be epoxied to the inside of the hull. I have a flat bottomed dory, I figure the thickness of the bottom at 3/8", maybe a bit more. Can I build a little "pool", place the transducer inside and fill it with West System epoxy?

Any way to test to see how this type mounting would work before epoxying it in place? I read somewhere about placing the transducer in a bag of water and let it sit on the bottom. Will this give an accurate indication of how it will perform?

Thanks, Rob

warthog5 · 08-12-2004, 11:27 PM

A flat bottom Dory. Is it wood? It will not shoot thru wood.
I for see a problem with the west Epoxy. It has a quick set time and when you stir it, you induce
air bubbles into the mix. Because it sets so quick, that could be a problem. Most manufactures like Furuno
say to use silicone.

Glen E · 08-12-2004, 11:34 PM

see the last issue of motorboating - some guy had good luck in mounting a transducer in a piece of pvc and immersing the ducer in silicone..sounded good..last month I think...go searcht he website onlinen in the boatkeeper section...

Recoil Rob · 08-13-2004, 12:01 AM

It's a glass dory.

Actually I mixed up some of the epoxy last weekend to test it. I put about 1" in a plastic cup and it took about 3 days to fully cure, no bubbles.

Saw the article in Motorboating, interesting idea. I imagine when he says silicone he means something like GE Silicone II sealant?

Rob

Glen E · 08-13-2004, 12:23 AM

I would think so..the only advantage of the silicone I can see is you could carve it out if you wanted - once it's set in west epoxy, it's a paperweight if it breaks...also the silicone would act as a bit of a cushion, I guess..

Thom · 08-13-2004, 07:57 AM

Rob,

If you mixed up a batch of epoxy, no matter what kind of super-slow-set hardner you might have used, and if it was an inch deep in the cup, it certainly would not have taken 3 days to set up, unless you are in the far far north somewhere. I'm serious, even with very slow set hardner if it had been mixed up and then set in the shade on a quite cool day it still should have been set within a couple of hours. Epoxy is progably a better medium to set the transducer in than silicon.

Thom

MLauman · 08-13-2004, 09:45 AM

You could try to duplicate the Airmar P79 setup. Attach a piece of PVC pipe (they like to use GE silicone II) to the hull. Plop in the ducer and fill with mineral oil. You could then put a PVC cap on top with a slot for the wire which could be later sealed with silicone. You would need to make sure that the ducer couldn't bounce around, but I don't see why this wouldn't work on a flat bottom boat. And it would be easy to remove and redo if necessary.

Recoil Rob · 08-13-2004, 10:34 AM

Quote:

Thom - 8/13/2004 7:57 AM

Rob,

If you mixed up a batch of epoxy, no matter what kind of super-slow-set hardner you might have used, and if it was an inch deep in the cup, it certainly would not have taken 3 days to set up, unless you are in the far far north somewhere. I'm serious, even with very slow set hardner if it had been mixed up and then set in the shade on a quite cool day it still should have been set within a couple of hours. Epoxy is progably a better medium to set the transducer in than silicon.

Thom

Perhaps "setup" was the wrong term. I probably should have said "full cure" meaning I could no longer get a fingernail to stick into it. It had set up but was still a bit pliable within 24 hours. This stuff has been sitting around for 4 years and was mixed by eye, not the pump system. I just wanted to see if it would set up at all.

The transducer by the way is a torpedo shaped affair and will not fit into a PVC pipe (which I really don't have room for in such a small boat). I thought all I'd have to do was sink it halfway into epoxy in a small trough fashioned from wood. It's beginning to sound like this thru the hull stuff is more of a last resort set than SOP.

Thanks, Rob

Harpoon · 08-16-2004, 04:18 PM

If it is solid glass it will work absolutly perfect.

I have one in the bilge of my Parker. It is great.

Thom · 08-16-2004, 04:54 PM

I wouldn't call it a "last resort" at all. In fact a good number of guys will say that its the only sensable way to mount a transducer. I don't know if I agree with that but I will tell you that I removed a perfectly good thru-hull transducer, glassed the hole shut, ground out and reglassed about a square foot of the hull's bottom, and sealed in a factory mounting tank (filled with mineral oil) in my boat just to make the switch over to an in-hull mount. This far into its first season on the boat I'm glad I did it. I used to think of in-hull mounting as the least desirable method, now I'd put it at least equal to thru-hull and maybe better. Of course it moved a transom mount to the bottom of the pile.

So, from my point of view, which is to say this is opnion only, here is the order of methods by which you might mount a transducer from best to worst.

1. In-hull liquid contact/thru hull
3. In-hull directly glued to the bottom
4. Transom mount direct to transom
5. Anything behind a step

Thom