Can you access the under side of the areas you might want to mount them to? 1st, buy HiTeks. Then take the bases and cut pieces of plywood a bit larger than the bolt pattern on the bases. Drill the plywood then drill the top rails of your boat. Insert the stainless steel bolts all the way thru the base, boat, and plywood and put fender washers on the bottom of the bolt, next to the plywood. Lock it all in place with nylon locking nuts. Good to go.