"Tilt" transducers...
 

....very sweet. Most of us are familiar with the "traditional"
through-hull transducers, the one that typically require a fairing block
ahead of them. These devices typically stick out from the bottom an inch
and a half or so, and are shaped like a double-ended boat. They can
create quite a bit of turbulence under the boat.

Well, if you are equipping a new boat, check out the AirMar "no profile"
transducer. They're through-hull, round, and have virtually no profile
in the water. No turbulence. There are models that shoot straight down,
and models that shoot down at several angles. We put one on the new Yo
Ho, instead of the typical transom transducer, and I gave it a workout
today. No matter what I did, the transducer never lost bottom, which is
quite an improvement over the transom mounts, which sometimes no. No
rooster tail, either, and it seemed to work properly in reverse, too,
despite turbulence from the prop. Bottom and temp gauge, no wires on the
transom, no holes in the transom.

They're about $100 more retail than a transom mount. When you drill the
hole, you have to be mindful of where the boat sits on your trailer, but
other than that, no real worries.