The Panama Canal extends across the Isthmus of Panama, connecting the Atlantic Ocean (Cristobal on the Caribbean Sea) and the Pacific Ocean (Balboa). However, geographically Pacific and Atlantic oceans are not in the same level; the Pacific Ocean is a little higher than the Atlantic, thereby compelling ships to get up over the terrain of Panama, which is higher in the middle of the country.
The Panama Water Lock System is considered one of the greatest engineering services undertaken at that time, purporting to the needs of the ships to save transit-time compared to the 8 thousand mile journey around South America.
A diagram of the cross section of the Panama Canal will feed you with the idea:
There are a total of 12 sets of locks in the Panama Water Lock System, among which only six massive pairs of locks are used by ships for transiting.
Each of this water locks are 1,000 feet long and 110 feet wide and is to be filled or emptied in less than 10 minutes. Each pair of lock gates takes two minutes to open.
A fender chain, weighing around 30,000 pound, at the end of each lock prevents ships from ramming the gates before they open. Water flows from artificial lakes through 18 feet wide culverts and is not allowed to be pumped into and out of the locks. Ships are pulled with the help of electric towing locomotives, called “mules”, by cable through the locks.
On an average, ships require six of such mules, three on each side. The canal locks together raise ships from sea level to a height of about 26 m (85 ft).
The whole operation of the Panama Water Lock System works in six steps.
1. Approach towards the lower chamber of the canal locks
2. The valve of the first chamber opens and water flows by force of gravity from the higher chamber to the lowest one, bringing the water level to the sea level.
3. Gate opens, ship enters the chamber, and the gate closes behind it.
4. Valve of the next chamber is opened to increase the water level of the first chamber.
5. Next door is opened and the ship enters next chamber.
6. Water level is equalized and the ship finally exits the lock and enters Gatun Lake.
The process is described vividly below
- After a ship enters the first (sea level) lock chamber at the Gatun Locks, on the Atlantic end of the Panama Canal, the watertight lock doors are closed by the lock-master and a valve is opened, allowing water from the adjacent second lock chamber, 28 feet above sea level. Water flows through underground pipes into the first chamber until the water levels equalize. However, no pumps are used here; the entire operation of equalizing the water levels between the locking chambers on the Panama Canal depends on the principles of gravity to move the water and on the fact that water seeks its own level. When the water levels of two adjacent chambers are equalled, the water stops flowing of its own accord.
- Following the equalization of the water levels between the first and second chamber, the valve gets closed by the lock-master to the first chamber and the watertight lock doors between the first lock chamber and the second lock chamber are opened subsequently. This process allows the ship to proceed into the second lock chamber. The first operation is repeated then between the second lock chamber and the third lock chamber, which raises the ship to the level of Gatun Lake. After the closure of the final valve and opening of the watertight lock door, the ship is raised 85 feet above sea level, and is able to continue its journey to the Pacific.
- Same process inversely is followed in order to send the ship back to sea level. At the Pedro Miguel Locks on the Pacific end of the canal, when the ship enters the first chamber, the watertight doors are closed by the lock-master. Next, the valve gets opened on that lock chamber, allowing water to drain from the first lock chamber into the relatively lower second lock chamber. After the water level between the two chambers is equalized, the watertight doors are opened allowing the ship to continue transmit down the Gaillard Cut to the Miraflores Locks, where the operation of lowering the ship to sea level is completed.
References: pancanal, panamaliving, howstuffworks, ehow