what sealant to us to fit depth transducer to grp hull

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mariog

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Can anybody advise what sealant, silicone, epoxy etc to use to fix the raymarine depth transducer to the inside of grp hull. Should I cover the whole face of the transducer and press it against the hull to avoid air traps?
 
Araldite to a dry abraded patch of the hull worked for me.
You can fill a bag with water and plonk the transducer on it to check it works well in the intended location.

I don't know about silicon sealant. I would have thought it poor as a sound transmitter..
 
You can use good quality marine silcone sealant wich releases well(it's the sealant of choice for NASA transducers) or Sikaflex wich doesn't.With any sealant it's a good idea to put the transducer in by hand and allow the goo to go off a bit and only then tighten up.this leaves a sort of a gasket in place wih can be done up a little in the case of a leak.
 
i find sikaflex better than araldite as it is difficult to mix araldite without getting tiny air bubbles in it, also if bonded with sika it can come off later (just).
 
I would not use anything too powerful - I removed an old transducer that had ben epoxied into position and ended up with a 10mm deep crater to repair as it pulled away some of the hull when removing it, fortunately the hull is rather thick in that area but still a repair to make! In future I will use a little polyester resin thickened and onto the hull not cleaned up so as to not get max adhesion.
 
My Vote is a decent quality silicone as I have used four times previously and in current boat with a Garmin 160 f/finder
big blob and then twist and settle transducer in as silicone sets

Cheers Joe
 
Oh yes sorry, I didn't read the post thoroughly.

OK, have a look on the Airmar website. You may have a normal thru-hull transducer but using their installation instructions for their specially designed inside hull transducer they have a number of very useful things to check out before installation.

http://www.airmartechnology.com/uploads/InstallGuide/17-217-01.pdf

1. Check the transducer is working and look at the bottom reading echo.
2. Find a location inside the hull and test it by using vaseline or placing the transducer in a bag of water and wetting the surface of the inside of the hull.
3. If the preformance is acceptable then continue with install position. If performance is reduced try somewhere else or check that the hull is not foam cored at that point.
4. For core hull, cut the inner core oversized and glass in or epoxy the foam to waterproof it.
5. Use silicon for bedding the transducer and watch that there are no air gaps when pumping sealant.

Hope that helps. Those are very good instructions.
 
Yes, you're right ,didn't read the post properly.For a in hull transducer I would set the tube in epoxy putty.That's what I always do and it works very well.I'm always careful that there's no putty under the transducer,only around the outside tube.
 
Araldite is just fine---but make sure that you get the "slow cure" rather than the "rapid set" variety. The "rapid" will have air bubbles in it from mixing with the hardener.
 
I set my NASA transducer in silicone sealant. It works fine and seems to be strongly stuck.

NASA recommend you stick a bit of chewing gum to the face of the transducer to test the spot you intend to use before cleaning off the gum and fixing permanently.

My thinking was that if I did want to move it for whatever reason I could probably release it with a sharp blade without wrecking the transducer head. Epoxy would be stronger but very permanent.
 
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