Using a grounding plate would be easier.
It is a metal plate with two bolts. Typically about 12" to 18" long by 6" wide.
Find a spot on the hull below the water line, measure and drill the two holes (typically about 3/8") slather on some 3M 5200, push in the plate. On the inside of the hull tighten down the bolts and attach your ground cable to one of the bolts.