frank1492 wrote in
:

Am I just doing something
wrong in applying the Silicone II?

I find their recommendations quite strange. I made a blob of 2-part Epoxy
mix in the bilge of the Sea Ray and pushed the little Garmin in-hull
transducer face directly into the epoxy blob. I know it's permanent but
you can always put the next transducer right next to it 5 years from
now......well, the new owner probably could...(c;

Not sure why Silicone II. Seems too soft for good sound transfer to the
hull, to me.

Before you commit to any location, what you should do is flood the hull
with a couple of inches of fresh water and go for a ride. While someone
else is driving in 50' of water or so, move the transducer around under the
water inside the bilge until you get the best picture and find the best
"hotspot" for both best picture and best mounting position. Many places
work better than others at transmitting sound through the hull.

Mineral oil is:

A - Inert
B - clear so if it oozes noone will know.

I'd also be tempted to use what the Navy uses on their transducer coupling
fluid....K-Y Jelly....the industrial strength equivalent, which is lots
thicker. It, too, is inert and clear.