Loss of bottom plot and depth

[Jim_MI]

Hi Larry -

I also fish from a kayak and have had problems with through-the-hull installations like you describe. Marine Goop has a tendency to form microscopic bubbles over time. That is why it changes color from clear to whitish. These bubbles apparently change the acoustic impedance leading to reduced sensitivity.

After removing the Goop but before returning for repair, try just hanging the transducer over the side of the yak to see if your signal has returned to normal. If so, then you will probably need to use an external mounting system, such as the Ram Transducer Arm. You could also try a "wet mount" inside the hull, as follows: Get a piece of closed cell foam, like they sell in garden supply shops for kneeling on. Trace the transducer profile on it and cut that out to form a through-and-through [censored] in the foam block. Cut the foam to be about an inch wider all around, forming a collar. Goop the foam collar into the bilge so that it forms a waterproof seal across the hull contact area but permits you to slip the transducer in and out. When you are headed out, pour a couple ounces of water into the cutout space and squish the transducer in, forcing all air bubbles out around the edges. Then your transducer will shoot through water --> hull --> water --> fish. This is much cleaner acoustically than goop --> bubbles --> goop --> hull --> water --> fish. It works well with standard sonar but I have never tried it with CHIRP. Pull the transducer after every trip to let it dry out and you're good to go.

Good luck!

Jim