Shoot Through The Hull

I'm not a fan of the epoxy method of attaching the 'ducer directly to the hull, although it's definitely the easiest. I prefer to mount the 'ducer in a plastic pipe, then fix the pipe to the hull.

Fit a piece of plastic pipe to the hull where you want the 'ducer mounted. Put a wire brush on your drill and clean/roughen the hull where the pipe will attach. Mount the ducer in the pipe in the same orientation you would have it if it were hanging off the transom. Seal the mounting holes with 5200. I leave 1/2" or so between the 'ducer and hull.

Swab the place of attachment liberally with acetone. When it dries use 5200 to fix the pipe/ducer to the hull. Fill the pipe with water or antifreeze and you're done. If you want to keep the water/antifreeze in the pipe from evaporating, drip/pour enough hot wax on the liquid in the pipe to seal it. I don't bother with the wax; I use water and only need to refill it once a season.

Don't like the spot? Tear up the pipe, clean up the 5200 on the hull with the wire brush and try another place.