Ron,

Thanks for the answer but I *think* you and I are talking about
two different things. Unless I'm not catching what you mean.

This transducer is NOT a Shoot-Through-The-Hull type mounted inside the
boat. (Also called an "In Hull Transducer" ?? )

It IS a THROUGH-HULL type where there is an actual hole cut in the wood.
The transducer has a "mushroom" head on it and a "stem." The "stem" is
pushed through the hole in the hull and the mushroom head sets outside the
hull.

With this type there is not the concern of air-bubbles in the wood or in the
epoxy/sealant because the transducer head makes direct contact with the
water. (Though there are still concerns about bubbles that are IN the water
from a bouncing hull or the prop.)

What the directions seem to be concerned about is that because the stem of
the transducer is actuatlly going THROUGH the wood...if that wood swells it
might put too much phyisical pressure on the stem of the transducer and
physically break it.

That makes sense to me on a planked boat where the wood swells a LOT and
where the thickness of the wood is quite a bit.

My question is: Does the same hold true for 3/4" plywood? Seems to me that
A) Plywood hulls probably don't absorbe much water or swell much. And B)
the plywood being only 3/4" thick would not put the pressure on the
transducer like a 2" or 3" thick hull would.

Gary