From the "How Do" Series at Seadolby.Com

How Do Locks Work

By Ieuan Dolby

Locks are found all over the world - I am not talking about door locks please! Locks are the means by which ships can enter inland waterways or transit from one level to the next on a canal whose level is controlled. There are big locks and there are small locks but they all operate under the same principle.

If there are two levels of water, one high and the other low then the ship must enter a lock. The lock is a container that has two gates, one at either end. The ship enters at the low end when the gate is open. At this time the water level in the lock will of course be the same as that of the low level water. When the ship is inside the lock the gate is closed. Water is then pumped into the lock and the ship will rise up. Once the level of the water is the same as the high end the other gate is opened and the ship can proceed out.

The two gates can never be open at the same time. If they are open at the same time all the water from the high end will flow into the low end to try and balance out. If this happened the river or canal will try and empty itself which will cause serious problems for all the ships already there.

Some famous locks can be found on the Panama Canal because the Pacific Ocean is at a different level to the Atlantic Ocean and in Holland where the country is a network of inland waterways.

A vessel entering a Lock
Photo Copyright © Ieuan Dolby, 2007

The Stern gate is Closed and the Water level rises

Once the Level is reached the High gate is opened

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