I have learned in the AB ribs, that is a solid chunk of bilge glass in front of the transom. I have epoxied in a few transducers in this rib with good results. I make a round mini mold, tape it in well and fill it with epoxy, slow cure. A hour later, when all the air bubbles are gone, I slowly insert the puck ducer., ensuring not a chance of the smallest air bubble. I tried one Nirvana once,, no joy. Had to mount a transom ducer. Same display on both brands (Eagle digital) and the transom mount did work better plus speed and temp functions. These are lil boat bottoms and make a difference on a simple hull bottom. Larger boat mfgs can push the resin one way on Monday, push it another way Tuesday and backwards on Thursday. You will probably see a difference in all hulls when trying to shoot thru the hull. Can you hear me? Can You hear me now? Glad those who have an inside pucks, it is working. Still,,, Nothing beats an outside mounted and properly installed ducer. Now, a properly installed external ducer is another subject.