Rather than epoxy -- hard to remove if necessary-- you can put a wad of
petroleum jelly on the face of the transducer, and after pressing it to the
hull, squirt something like silicon around the rim of the transducer to
secure it.
My boat was struck by lightning once, and one of the exit points was the
thru mounted depth sounder. Wasn't much left to keep the water out. I
remember wondering why this particular locker seemed to have more light in
it than I had previously noted. Understood why at next haulout. I now rather
favor inhull transducers.

"frank1492" wrote in message
...
I apologize for this long delay in responding, but I have been without
land-line phone service since Thursday night, hence no Internet. It
was just restored this afternoon.
Thanks for all the replies (which I have printed out and
studied.) I would certainly feel capable of removing the transducer
(which seems clearly to be the problem.) DMI Electronics (the
reincarnation of Data Marine) has the transducers for $150, and I have
actually seen them as low as $129.
Because the boat will have to be pulled ($150) in order to remove
the transducer (from the bottom), which would make total of $300, I am
looking at other options. Most obvious is to buy a new complete unit,
display and transducer. I'd like your opinion on a couple of points,
however, before I go that route.
(1) Some of these have "in-hull" transducers which are simply
epoxyed to the inside the hull. If these are accurate, they sound
appealing. Your thoughts?
(2) As I occasionally fish (but am by no means "avid") I am
wondering why I don't just buy a fishfinder. Some don't have
fractional readouts, and I would avoid those, but for those that
do read tenths of feet, is there any reason these would be less
accurate than a dedicated depth sounder? To get a good
depth sounder plus all the other features (including temp) is
very tempting UNLESS you tell me the depth sounders on these
are junk.
Again thanks for your past ( and possibly future) help.
Frank