I got tired of going to a boat tie ups or docking with pylons in the way and having to take all the boards off the racks, so I said F-it, I'm getting some swivel board racks. Then I looked at the prices. $400+ each... ha Nope! A couple inspirational brain beers later I decided to make a set myself and they are working great! I can hang my entire weight on them and they are rock solid.
All materials came out to be roughly $35 including stainless screws, thrust bearings, and spring locking pin.
Video and pictures attached.