Mounting In-Hull transducer

[Rex Delay]

I just bought a Lowrance chart plotter. The manual says that to mount the transducer in the hull, epoxy it to the inside of the hull. Others have suggested that using silicone is better. Any input?

[s/v Breakaway]

Suggest you do what the mfg says.

[Jetexas]

I just installed a Faria in-hull transducer this weekend on my boat. The instructions say to mount the outer ring with silicone and specifically says that epoxy is too brittle. Once the silicone is dry, you then fill the ring with propylene glycol and lock the transducer down into the ring.

However, both a guy at West Marine and a guy down the dock said you could just slather the bottom of the transducer with epoxy and stick it straight to the hull but that you couldn't pull that move with silicone because the transducer can't shoot through silicone.

I didn't try the shortcut method and went with silicone on the outer ring.

[Lancerbye]

A through hull transducer mounted inside shooting through the hull will only work if you have a good solid glass hull. If it is a sandwich or cored type you will have to remove the inner layer to get to the outer layer. The performance will never be as good as a through hull fitted transducer.

[Charlie]

I would test it by placing a ziploc bag full of water on the hull where you are going to put the transducer and see if it works. I tried this in a few different spots on my boat and it worked in some but not in others.

[Rex Delay]

I have tested the location with the baggy full of water and the engine sump area works fine with good access. Just not sure which way to attach - guy at West says silicone best, manual says epoxy. Silicone would be easier.

[belizesailor]

I would go with manufacturers recommendation....after all they designed and built it.

That said, I have mounted transducers in-hull with just a piece of PVC cut to fit, sealed to the hull with 5200 or similar, tacked the transducer in place with a few dabs of silicon around the edges, and filled with water or mineral oil -- worked great. The one on my H33 is mounted this way. I even "temporarily" put one in the shower sump once....it's still there almost 10 years later and working just fine...except that someone has to take a shower at the start of each season before the depth sounder will work!

[hugosalt]

Installed transducer in hull many years ago and still in service.
Used silicone...trick is installing in solid glass hull and making sure it does not have any voids or move before silicone sets.
Also helped friend install his, went by the manufacturers recommendation and epoxied in...you get one chance to get it
right....and we did. All in all I'm a fan of the silicone install.
Very accurate readings. Charlie has it right using ziplock bag
to sound before install.

[brankin]

Almost all transducers are made by Airmar. Cross reference your unit to their transducer and follow their instructions. In my case with a p-49, I mounted the transducer to the hull with a polysulfide (could have used silicon) and then filled the unit with mineral oil.
Works perfect with the solid glass hull of and Endeavour 43 and a standard horizon cpf-190.

[bobconnie]

Ive done both styles of mounting transducers, inside epoxyed, and 5200. and thru hull. I personaly prefer thru hull but both work ! I just feel better knowing Nothing is in the way of my signal. just my own Idea but over the years Ive come to feel this way. but again thats a personal choice

[Cheechako]

I have epoxied a few now, no issues and no growth on your transducer that way. Look for a spot where the glass looks very solid and resin saturated. Grind a flat spot... and stick it on there.

[Mike OReilly]

As has been mentioned by others, the real key is to ensure you have a solid connection to the hull (assuming the hull is solid glass). You need to avoid any voids, wether you use epoxy, silicon or something like 52/4200. Doesn't really matter as long as the bond is without voids.

On our previous boat we ran with a shoot-thru-hull transducer placed in a water well. We did this for years. We eventually used a polysulfide to stick it in place.

Personally I would be hesitant to epoxy a transducer in place. Would be a real pain to remove -- although I suppose it would still be easier than a thru-hull transducer.

[Ziggy]

Originally Posted by Rex Delay

I just bought a Lowrance chart plotter. The manual says that to mount the transducer in the hull, epoxy it to the inside of the hull. Others have suggested that using silicone is better. Any input?

In either case you need to find a spot that's nearly level (small deadrise angle), otherwise you'll get an offset beam, inaccurate depth readings and loss of sensitivity.

Here's Airmar's advice on adhesive:

CAUTION: Do not use:

• “5 minute” epoxies because they are too brittle.

• RTV (silicone) adhesives because they absorb most of the sound energy.

A hard adhesive, like the epoxy supplied, transmits sound best.
However, winter temperature extremes and flexing on trailer rollers can cause it to delaminate. Soft adhesives absorb sound and will greatly reduce performance. To compromise, use a viscous slow-cure epoxy or a fairly rigid one-part adhesive sealant. In cold climates, a one-part polyurethane adhesive, such as Boat-Life’s Life Seal®, may be best.

Personally, I'd follow Airmar's advice.

[Ziggy]

Originally Posted by Mike OReilly

We eventually used a polysulfide to stick it in place.

One problem with using polusulfide is that it attacks many plastics. I think 3M 4200 might be a better choice. It can be removed with DeBond if you get desperate.

[Mike OReilly]

Originally Posted by Ziggy

One problem with using polusulfide is that it attacks many plastics. I think 3M 4200 might be a better choice. It can be removed with DeBond if you get desperate.

Funny Ziggy, I just checked our records and it was 4200 that we used, not polysulfide.