Britannica Sources used in this answer

What steps does a vessel follow when passing through a canal lock?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

View of Utrecht's Oude Gracht canal lined with historic brick buildings, arched doorways at water level, and boats moored along the canal edge in the Netherlands. — canals and inland waterways The *Oudegracht* (Old Canal), Utrecht, Netherlands.

When a vessel passes through a lock, it follows a specific sequence of operations designed to safely transition the boat between different water levels:

Approach and Entry: The vessel approaches the lock, guided by visual or physical signals that indicate whether the lock is free and which chamber to use. Once the lock is prepared, the gates are opened to allow the vessel to enter the chamber.12
Securing the Vessel: Upon entering, the vessel is held steady against water turbulence using ropes attached to bollards (mooring posts) or mooring hooks located in the lock walls.1
Leveling: Once the vessel is inside and the gates are closed, the water level within the chamber is adjusted. To raise a vessel, the lock is filled to the level of the upper pound; to lower a vessel, water is drawn out until the chamber level matches the lower pound. This process is controlled by operating sluices.2
Exit: After the water levels have equalized, the gates at the opposite end of the lock are opened, allowing the vessel to depart.2