Success! The instructions for gluing the transducer in-hull worked perfectly. NorCross, you might add a sentence about cleaning up the petroleum jelly!
Thank you to whomever posted this. Your post was a big help in placing the transducer in my Yamaha:
**Customer Notes: "I contacted Yamaha and they suggested that the transducer should be fitted in the pump section of the craft as this was a single skin area and the engine bay is double skin/"
OK, I'll try it. I found an open, accessible spot and tested with petroleum jelly per the instructions. It worked so well, I seriously considered leaving the petroleum jelly and taping the transducer in place. No, I cleaned up the surface and used 2-part epoxy. I waited a few hours and tested again at the boat ramp. Again I received accurate depth readings. So far, I'm very happy with the results. A photo of my location is attached.