I wanted my trolling motor bolted down, but didn't want to have to pull my anchor locker to reach nuts for removing, so I made this backer out of 1/4 aluminum. I drilled and tapped the two center holes for 1/4 inch bolts to hold the plate in place when the trolling motor isn't in place. The outer holes were drilled and tapped for 5/16 trolling motor mounting bolts.