I'm not really sure how long the 2x4 is. Doesn't need to be big. Mine's a foot, maybe. I put it flush to the outside of gunwhale, put the clamp mount over it, and screw 'er down as tight as I can get her. Not ideal, but for a cheap, lazy-man's solution it seems to work pretty well. I wonder what would happen if my ball got stuck or snagged. I suspect it would not be pretty.