Lock Operation

From Lyon to Avignon we did pass 12 locks. It's exciting to follow the ship passing the locks either downstream or upstream - Fascinating to watch the ship enter and exit the lock with only 20 cm at each side and were little headroom.

This video does feature downstream passage of Ecluse de Caderousse  just before entering Lyon and Ecluse de Beaucaire upstream when sailing from Arles back to Lyon.

Bollène Lock is the deepest of the Rhône river's locks;  23 meters from top to bottom. Built in 1952 as part of the Donzère-Mondragon Dam.
The lock is deep, grey and formidable,  dripping and slimy - yet beautiful in its austerity. 

Locks are used to make a river more easily navigable, or to allow a canal to cross land that is not level. 
The lock is used for raising and lowering boats between stretches of water of different levels on river and canal waterways. The distinguishing feature of a lock is a fixed chamber in which the water level can be varied.
The principle of operating a lock is simple:
When water level is correct the entrance gates are opened and the boat moves in. The entrance gates are then closed.
A valve is opened, this lowers the boat by draining water from the chamber - or is filling the chamber to lift the boat. The exit gates are opened and the boat moves out.