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"Teaching people about the world in which we live."

Locks!

Locks allow a ship or boat to travel from one water level to another in a canal or tamed river. They were invented by the Chinese in the 10th century and also by the Dutch in the 13th century, so they've been around for 1000 years! Similar locks are still used every day on major shipping routes such as in the Panama Canal, the Great Lakes, and rivers around the world. Here's a drawing of a typical lock.

As you see, the lock consists of two sets of gates (doors) to hold the water and two tunnels (called sluices) for water to flow into and out of the lock. Just to be confusing the doors that let water into the sluice tunnels are called gates as well. On small locks the sluices are sometimes gates that are built into the lock doors themselves. For a ship to go up the locks as shown, there are a few steps that must happen.

1. The bottom sluices are opened to allow the lock to drain.
2. The lower doors can then be opened.
3. With the doors opened, the boat can enter the lock.
4. The lower doors and bottom sluice gates are closed.
5. The top sluice gates are then opened so that the water level rises in the lock, floating the boat up to the next level.
6. The top doors can now be opened. The ship is then free to exit the lock on the new level.

To go down the lock the reverse happens. The lock is filled, the boat enters the lock, then the lock is drained, allowing the boat to exit on the lower level.

Lock demonstration game!

Lock Flights

Sometimes locks are arranged in groups of two or more locks known as flights. This allows the boat to be raised to a higher level, but becomes more complicated to operate.

1. First the boat must enter the bottom lock.
2. After the boat is in the lock, the doors can be closed and then the lock filled. In order to fill the lock, water must be brought all the way from the top canal, so all of the upper flood gates must be opened.
3. When the bottom lock has been filled, the flood gates can then be closed, the door opened, and the boat can move into the next lock.
4. The doors are closed again. This time only the two top sluice gates need to be opened to flood the middle lock.
5. The gates are then closed, the lock door opened and the boat can sail into the last lock.
6. After one more cycle, the ship is free to sail on.

See how locks operate yourself by playing with our lock games:
Single lock demonstration game!

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