Transom Mount Transducer mounted inside the hull in a bed of 'jelly'

[elskede]

hello: i was told years and years ago that a transom mount transducer could be mounted inside a boat in a bed of jelly (or in other words a bed of clear silicone.
does anyone have experience with this?
in other words to clarify...the transducer would be placed inside the boat down in the bilge and in a 'bed' of silicone and it would 'shoot thru' the hull and fiberglass and bounce back for a reading...mounted inside the boat in the bilge.
thx.
the reason i ask i i own a westsail 32.
i bought an HDI lowrance gps that included a transom mount transducer. i'd like to put it in a 'bed' of silicoone next to my thru hull transducer if this actually works.

thank you.
any advice or more to the point EXPERIENCE would be appreciated.
stephen
feel free to email me directly asap; kenneth549@gmail.com

[Hoofsmit]

Hi
Yep, I did mount my last Garmin transom mount with just a very thin layer of marine grade silicon it worked fine and another old lowrence that was a thru hull flat disc type.
This was in a fast motor cruiser, so the hulls were both thick Grp, obviously it's important not to allow air / gaps between the surfaces and mount as flat as possible, but it worked fine for me.
Don't know if it would work with other hull materials like carbon fibre or even wood?



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[egodsey]

Stephen,

I built a frame (with no bottom) out of 1/8" plywood, glued it to the inside of the hull with RTV, put the Garmin depth transducer inside and then covered the transducer with melted toilet bowl ring wax. That was four years ago. The depth sounder has been working flawlessly ever since.

Regards,

E. Godsey

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[bobnlesley]

We've done that, or similar at least:

Our last yacht had no echo sounder that'd been installed within an oil-filled tube, inside the hull - no hole through the bottom, yippee! Sadly the oil had leaked out, so the transducer wasn't working; no doubt because the plastic tube had been glassed-in in the centre of a locker space, so restricted use of said locker and also left it vulnerable to damage.

I'd heard a similar anecdote/rumour to yourself, though it was to set the transducer in epoxy, but not wanting to risk damaging/losing the transducer if it didn't work as implied, I originally tried setting it in silicone to 'give it a try'. All I did was clean-up a section of hull - because you're not trying to drill holes, or do glass fibre work, you can pick an area of wasted-space, in a really out of the way, well protected location (ours went under the heads, behind the pump) then pumped perhaps 1/3 of a tube of cheap silicone into a big blob in the spot chosen, left it for fifteen minutes, then pressed/screwed the transducer vertically down into the blob of silicone and left it alone for a few days.

It worked fine for the next ten years and we never did get around to making the job 'permanent' with epoxy, in fact, we re-fixed it after about eight years again with silicone - no problem with the original silicone, but it was 'in the way' when we wanted to replace a seacock, so we cut the whole thing out with just a modelling knife, cleaned off 90% of the old silicone and when the job was done, just stuck it back in place.

Given the choice, I would always install one this way (it's one less hole in the bottom!) and the only slight disadvantage I would report is that the unit will lose itself at a lesser depth than it might if you used a through-hull transducer, though that may be just a presumption on my part; comparing a vey old and much new transducer? Our current yacht has exactly the same make, though later model of echo-sounder fitted, but in a through-hull installation and stops reading at around 120-130m/400-450' depth, whereas the old one sat inside on its blob of silicone and reading through the hull, rarely read beyond 90-100m/300-350'; once the water's that deep, who cares?

[Mike OReilly]

I've never mounted a transom-mount transducer this way, but I did mount a flat one designed to shoot-thru-the-hull. My understanding is that the only difference between these transducers is the shape. And I have heard of people mounting transom-versions as shoot-thru. It's just that it's a lot harder to get the orientation right, and to have them stay in place.

So yes, I believe you can do as you suggest. Make sure you are shooting thru solid fibreglass (I'm pretty sure all Westsail's are solid hulls), and make sure their are no voids in the silicone. Once it's working well you could epoxy the transducer in to place for a more secure fitting.

[sailortype]

I have read in maunufacturers instructions to specifically NOT use silicone... just cannot remember the reason. Epoxy works. I have mine mounted in an 4" ABS tube with a cap glued to the hull and it works fine. I am using water in the tube but mineral oil is a better idea, probably for dampening

[boeing1]

Have in installed several this way they have all performed well be sure that you do not get any air bubbles between the transducer and the hull most come with directions to install

[noelex 77]

It will work on solid fibreglass although the range is slightly less. As a test, if you take a plastic bag full of water seal it up with little air in it place the bag in the intended spot and put the transducer on top. There is no need to put the transducer in the bag, but make sure there is no air between the hull and transducer.

This test will show if the spot is suitable and the likely range etc.

[CREX]

Yup. Used that method in my Columbia 30. Eight years no problems. Dead accurate in the shallows but did lose alittle deep end range. Just cleaned up forward under bunk, nothing to bother it and pretty much at the bow where it should be. Just squeezed silicone and set it in. Voila! No air bubbles!!! Squeeze smoothly and continuously. Good luck.

[BudGates]

I mounted mine in a bed of silicone as stated above. The only thing that I added was a piece of dental floss going across the bottom so that I could use it to cut the silicone to relocate the transducer if I needed to. It worked flawlessly where it was but I did eventually use the dental floss when I sold the boat and relocated it in our new boat.

My transducer also included a water thermometer which doesn't work when mounted inside but to me that was pretty minor.

[wristwister]

A couple years ago I went through this on my Tartan 30. With a little trial and error I found a good spot at the bottom of the hull near the transom to mount the transducer. Because I wanted to try a couple different locations, I used toilet wax to mount the transducer. Yup, toilet wax, available at any hardware store for a couple bucks. That transducer is still held in with the stuff 2 years later. It's on my to-do list to permanently mount it with epoxy or silicone sealant, but I'll probably never do this as that toilet wax appears to be amazing stuff.

[Waboson HR352]

If you can fix a container to the hull you can use glycerine as the surrounding fluid for the transducer.

[The Garbone]

Toilet wax. I made a little volcano and stuck the transducer down into it. After reading this thread If I was to do over I would make a like corral out of tape and foam and pour in the melted wax. Probably the least chance of air bubbles. But it works and was easy so in the pile o wax she sits.


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[bratzcpa]

I installed my transom mount transducer by simply bedding it in a big blob of "plumbers putty". It has worked great for me.

I haven't seen any degrading of signal quality (inaccurate readings, or not enough depth) yet.

Very happy with the process and easy to remove if I want to upgrade or take the chartplotter/sounder with me when I sell the boat. And lots easier than a pond of oil/water.

~markb

[David M]

Any sort of material which can efficiently transmit sound will work. Generally speaking, the harder the material, the less will be the attenuation of sound. A hard bedding compound will transmit sound better than silicon sealant. The downside will be that if you ever need to remove the transducer that it might be more difficult with a harder bedding compound.