I was givin a small 2man boat. My question is about sealant. What would you use to put over the old stuff. Ihavent tried to remove any old stuff.The pic below is the worst spot. Also pictured is the old transducer mount,which will also be removed. Ineed something that can be used below the water line. Any recommendation are appreciated,thank you.

only thing I can think of is cleaning it really good and tying some clear silicone