|Those white things hanging off the side of a boat are called fenders. They prevent the unforgiving stone walls of a lock from scraping up against the hull of a boat. In most locks, there is flood guard, an elevation of the wall of the lock above the normal navigation water level. So, a fender hanging high on the side of the boat works just fine. But in the "interior" locks of a multiple set of locks, there is no guard, the water level can come up almost to the top of the wall. In this case, a boat with fenders hanging too high must lower them in order to protect the hull of the boat. This is what is happening with the lead boat - the crew of the boat and one of the lockstation staff are busy lowering the fenders.