I have a new old Lowrance X 48 and want to install the wide angle [20 degree?] thru hull transducer when the boat comes out of the water for bottom paint. What is the best/easiest location for it on the H3?. The instructions say not to install it behind other thru hull fittings. It comes with a heavy rubber gasket. Raymarine suggests using 5200 between the thru hull flange and the hull, but this forum recommends against that as too permanent. What is preferred to bed thru hulls that are permanently submerged in salt water?