If you are talking about the one on the outside of the hull, not the side closer to the middle of the boat but the one on the outward side of the boat, then here you go. On the end of the top of the crossbar there is a rectangular shaped access cover that measures approximately one inch square. It is pressed on and can be popped off with a screwdriver blade. Once lifted, you should find an allen bolt that goes through the crossbar and through the hull lip, into the nut on the bottom side of the lip.

I'm doing this from memory and it has been several years, so I could be less than accurate in my description.

GARY