Thanks to Larry and (again) to GBM. I guess I will try again
with the Silicone, one more time before calling. I gather
people have had some success using this as a permanent
adhesive, but I just can't imagine it. I do like the idea of
being able to move the transducer easily in the event that
the originally chosen location turns out to be N.G.
At the present time the transducer is sitting face down
in the bilge. At mooring the readings seem approximately
correct +/- about a foot. I won't be able to do much with a
retry of mounting over the weekend as I'm having guests. As
I am on Cape Cod with mostly sandy bottom, I use the depth finder
mostly to tell me when it's time to put the stern drive up as
I come into the beach, so nothing critical.
I'll be interested to see the readings I get when I get
under way. (Too windy to go out today.)
Will report back on everything.
Thank you again.
Frank
P.S. Will mount the base *exactly* to manu specs to
make sure I get the right angle. The Grady has a deadrise
near the stern of about 20 degrees.




On Fri, 28 Jul 2006 11:49:57 GMT, frank1492
wrote:

I am back! Thanks again to all of you who made suggestions
when I had difficulties with my LX-201. It turned out that it was
indeed the transducer itself!
Although I considered many solution alternatives (with your
help) I finally settled on trying an Airmar P79 in-hull transducer
because they told me it would be compatible with the LX-201.
Also, I preferred not to mess with the old thru-hull as it needed to
be pulled from the bottom and appeared to be epoxyed in place.
Initial tests have shown that the Airmar will work well as it
will be used on a non-cored Grady White with a solid hull thickness
of less than one inch.
The problem has been the mounting of the transducer. Airmar
uses a bottomless base with a flange that is secured to the
inside of the hull with adhesive. The base is then filled with either
mineral oil or propylene glycol (their instructions), and the
transducer snaps on over that such that its bottom face "floats" on
the liquid. Obviously whatever adhesive is used must make a permanent
seal between the hull and the base flange as the base itself has no
bottom.
Here is the problem. Airmar specifically states that epoxy,
or the previously recommended Boatlife LIfe Seal or 3M 4200
are *not* to be used. Only GE Silicone II is allowed! With an area
perfectly cleaned with 409 (the area has a gloss), I have tried to
mount the base three times, each with many hours of cure time.
Each time when I have added the glycol, it leaks out after a few
seconds as if it were reacting with the silicone. When the base is
removed, the silicone on the flange is a sticky mess.
It really doesn't make sense to me that silicone would work at
all in this application. So why not use epoxy? Is it just that it
would be permanent and if the transducer base had to be
moved or removed you couldnt get it off? Surely Airmar sells
replacement bases. (I will check tomorrow.)
Your counsel is much appreciated. Am I just doing something
wrong in applying the Silicone II? (Otherwise known as "Kitchen
and Bath.") Or am I correct that this is a bad idea for a permanent
installation and epoxy should be used?
Thank you.
Frank







On 2 Apr 2006 21:53:32 -0700, "DPFresh"
wrote:

Hello all, so as oppossed to drilling a hole in my hull for a depth
finder sensor, I should be able to set it up inside the hull as long as
the sensor is in some type of liquid right? IT will be able to tell
depths through the fiberglass hull right?

Thanks,
David