My only experience with a thru-hull transducer is one the previous owner installed. It was as far aft and as far outboard to the starboard side away from the keel as possible with access to it from the bilge (just forward and outboard from the livewell thru-hull pickup). Most of the time it worked great, but occasionally when we would come over the top of a wave, it would come out of the water slightly and would cavitate or create some sort of air bubble turbulence trailing off it that would cast a shadow on the prop. This would cause the boat to pull hard right while leaning hard left. It was always a squirrelly situation. The only way to fix it would be to back off the throttle to idle and start over. After 1 season dealing with that, we removed the transducer, patched the hull, and went with a transom mount. Transom mount works great, and we can maintain a bottom fix to about 400 feet while up on plane. This was all pre- trim tab install. Maybe if we had had trim tabs at the time, the bow would have rode a little farther down and kept the transducer from coming out of the water enough to create the turbulence. I will never know, but I've been happy with the transom mount for what we do.
