Well as they said in one movie: You pick the man with the biggest buns and have him sit on it. But kidding aside, this is why you do carry some scrap pieces of wood, canvas along with wedges and plugs. Plus plugs next to all through hull fittings also. Good maintenance means that you would never need them. But you never know.
Then you have all the jetsam & flotsam out there and coming down the rivers You can never be sure of what you may run into. From a tree to a steel container box.