Hi John,
If yours is like ours, which I'm sure it probably is, the bolt, in our case an eye bolt, passes through the track and is threaded into the steel plate which is under the gunwale.
I broke one trying to undo it and ended up having to drill it out with a cobalt drill and re - threading the hole. I just put a standard bolt in to replace it. I don't know what that eye bolt is for, I've never used it.
Cheers
Alan
Elyse SM437