Fish finder glued inside the hull

Jun 2, 2014
589
Catalina 30 mkII - 1987 Alamitos Bay Marina, LB, CA
Not a really important topic, but I was messing around with a fish finder transducer in my Cat30, and wanted to glue it inside the hull.
I used one tube of clear silicone then another tube I thought was clear but ended up being white because I wasn’t paying attention.
And I wasnt thinking when I squeezed it out and didn’t think about air bubbles, so being a little too late to undo what I just did, I decided to see how well it would or wouldn’t work. Worst case I’d let it dry and start over later. I pressed the transducer into the blob and tried to squish it enough to try to flatten out any bubbles under it, and the immediate results were really noisy.
I waited a day for it to mostly dry and checked again, prepared to rip it out, but it looks pretty decent today. A bit of noise, but looks good enough to use.
Here’s the install, and the before and after pics of the silicone wet and mostly dry:
F482FE8C-5458-4386-B791-E413B616C805.jpeg 9446C36B-D50D-4824-A425-6CDC03245385.jpeg 9CB50396-7A78-46F0-8F72-31B4BCCEFE80.jpeg
 
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Likes: Jim26m
Oct 10, 2011
619
Tartan 34C Toms River, New Jersey
Thru hull transducers work fine. I think you got a little carried away with the silicone.
End result is it worked.
 
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Likes: jonelli
Jun 10, 2017
174
Catalina 1980 Catalina 30 Mk II John's Pass / Tampa Bay
J,

I also have an in-hull transducer in my 1980 C30. I picked a spot on the STBD near where the fuel tank is located.
If unhappy with the noise, here's how I found the right spot.

I placed my transducer inside a Ziploc baggie filled with water. I then moved it around while checking the unit for good signal strength minus any noise & marked the spot. It's also possible that the bubbles causing this may in fact be in the fiberglass hull & knot a problem with the caulking..

Just a thought pal.
 
Aug 3, 2012
2,542
Performance Cruising Telstar 28 302 Watkins Glen
Those top lines actually look like a picture of the bottom side of your hull. Kinda neat.
 
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Likes: jonelli
Oct 24, 2010
2,405
Hunter 30 Everett, WA
I've used wax from a 99 cent toilet ring to stick it down temporarily (for a couple of years and also to locate where it will work well) and it works great. For a more permanent fix a glob of 3M 4200 has worked for me.

Ken
 
Mar 30, 2013
700
Allied Seawind MK II 32' Oologah Lake, Oklahoma
I've used wax from a 99 cent toilet ring to stick it down temporarily (for a couple of years and also to locate where it will work well) and it works great. For a more permanent fix a glob of 3M 4200 has worked for me.

Ken
I "temporarily" mounted the transducer for my GPS/fishfinder in a glob of toilet ring wax 5+ years ago. Still works like a champ.
 
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Likes: Kermit
Jul 23, 2009
857
Beneteau 31 Oceanis Grand Lake, Oklahoma
I think I used Shoe Goo. It worked for several years, until I sold that boat.
 
Mar 1, 2012
2,182
1961 Rhodes Meridian 25 Texas coast
ever try to paint or varnish on surfaces that have had silicone? Worse than trying to use 5200 (an adhesive) as a caulk..