none. Use a Stern PAD. period.transom mount
use 5200 or 4200 "caulk" is typically not used for below the waterline.What's the best caulk to use for mounting a new transducer on a Grady
+1none. Use a Stern PAD. period.
https://www.amazon.com/Stern-Pad-Ju...ocphy=9003992&hvtargid=pla-898369791530&psc=1