Thanks Tom,

I think my plan at the moment is:

A) Take my nylon mount-in/through-the-hull transducer and put
it in some kind of block of wood to see if there is any place
it will work. It very well may NOT work because of space between
it and the inside of the hull and/or because it won't work through
the ply wood.

B) If the above does not work I think I''m going to install the
nylon mount-in/through-the-hull and mount is through the hull.
I will leave a little extra space for the wood to expand (not
much).

Thanks,
Gary