As we cruised the Marne, we had to deal with sloping locks. Normally, locks have flat, vertical sides. We tie up to bollards at the top – and tighten or loosen our ropes as the lock fills or empties. Sloping locks are trickier. Going down, Aleau’s hull would scrape against the side as the lock emptied. Not what we would want to happen.
On the Marne, the VNF has installed floating pontoons. We tie to them and they rise or fall as the lock fills or empties. Makes life much easier.
As you will read later on, the Yonne also has sloping locks. And three of them do not have floating pontoons. We encountered them for the first time last summer. (See Chapters 169 and 175.) And we will again a little later on.