• Historic Shot of Canal Boat on the Canal

    Chesapeake & Ohio Canal

    National Historical Park DC,MD,WV

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How a Lock Works

A lock is an elevator for boats. It lifts boats up or down to the next level on the canal. There are 74 locks on the C and O Canal. Only one boat at a time can fit in the lock. Locks are 100 feet long and 15 feet wide. This leaves only six inches on each side and one foot at each end of the boat when it is inside the lock.

Watch a video showing a boat locking through

Unhitching the mules at the lock

Unhitching the mules  at the lock

After the mules are unhitched from the boat the boat enters the lock.

boat being guided into lock

Boat being guided into the lock

Using the ropes attached to the boat, Lock Keepers guide the boat into the lock. This prevents the boat from hitting the lock walls and causing damage.

boat in lock lowered

The lock keeper closes the gates. The canal boat is totally enclosed in the lock. The water is either lowered or raised depending on which direction the boat is travelling.

wicket closeup

Close up of the open wickets with water passing through

A lock key is used to open the wickets. Wickets are paddles in the bottom of the gate that allow water through.

boat leaving lock

Boat exiting lock


When the boat reaches the correct level, the lock gates are opened and the boat exits the lock. It takes about 10 minutes for the boat to "lock through".

Did You Know?

Monocacy Aqueduct along C&O Canal.

Aqueducts are water filled bridges. Aqueducts carried the canal and boat traffic over major waterways, like rivers. Of the 11 aqueducts built along the canal, the Monocacy Aqueduct is the longest at 516 feet, its seven arches constructed mainly of stone quarried from nearby Sugarloaf Mountain. More...