depth sounder dillemna
I''m not a fan of bedding in-hull transducers with epoxy because epoxy is rather messy, and it''s hard to get rid of all the bubbles (and bubbles will render the transducer useless)
I dumped my old system (Navico) and put in a Uniden QT-206 depthmeter w/ in-hull transducer for around $75, I think from www.defender.com.
Be sure to test the site: the hull where you mount the transducer cannot not be cored or it won''t work. You can test it out with the transducer in a plastic bag of water before permanent installation.
Sand the surface smooth, caulk the supporting "tube" onto the hull, fill with mineral oil, and insert and secure the transducer. I also like that I can adjust the sensitivity of the unit as needed.