In hull transducer mounting/placement .

[Skools Out]

there's an epoxy you use to hold them on the bottom and yes you must have the transducer epoxyed in with no voids or air pockets between the hull and the transducer. I have them in my Sea Ray and they all work great. Your hull must be glass only (No Wood) an all have a certain thickness they will work thru read your box to be sure it will shoot thru the hull you may need to grind the hull to get it thin enough to work. good luck