My Inside Story Behind the Locks Look

at the Panama Canal


Panama Canal Diagram

Gatun's East lock chunk of concrete

All of the chambers of the locks of the Panama Canal were designed to be 110 ft wide by 1000 ft long. The Iowa’s are 108 feet wide and actually vary from 1” to 2 ½” over 108 feet along their length. One of the chambers of the Gatun locks, the East set and nearest the ocean has a chunk of concrete that sticks out from one side of the chamber. Approximately in the middle of the lock the concrete is about 6 feet high and 40 feet long. It reduces the width of this chamber to a point where a ship wider than 109 feet cannot pass through. This concrete could be cut away, but it has never been done. An Iowa Class BB cannot pass though this chamber (unless a well experienced lockmaster knows the secret) and must be put through the West set of locks only at Gatun.

I have said that an Iowa Class BB cannot pass though the East set of Gatun locks because of the chunk of concrete that sticks out from one side of the chamber.  That is not exactly right as it can be put through this set of locks.  It is just not easy.  The problem is that Iowa Class BB’s don’t come along every day to go through the canal.

The chances are very good that when one comes through the lockmaster was probably not around when the last one came through.  The older or more seasoned lock masters that are familiar with the problem would never tell the new lockmaster that there was going to be a problem.

To get the ship through the lock without a problem, it must be pulled over against the side of the chamber away from the chunk of concrete and then drug along the side of the chamber all the way through the lock.  This pretty well takes the paint off of a lot of the side of the ship, and this is where enough friction can be created to set the paint on fire.

Gatun Locks Panama CanalThe new lockmaster will center the ship in the chamber as he has been taught and start it through.  As I have said before a ship bounces, about like a Tigger in the Poo Bear comics, and when it hits one wall it will bounce off and hit the other wall because there is so little clearance.

Because of the bounce, in the East lock it is almost a sure bet that the ship will hang or lodge when it gets to the chunk of concrete.  The 6 ft by 40 ft long chunk only sticks out about 12 inches, but apparently it is just right to hang an Iowa Class BB.  It usually takes about half of a day to get it unstuck, at which time the lockmaster usually will pull the ship out of this lock and run it through the other lock.

When this happens it brings out all of the bigwigs and they want to know what went wrong.  The older lock masters think this is as funny as hell, as there is always an investigation when something goes wrong on the locks.  The lockmaster has a lot of paperwork to fill out and a lot of questions to answer. 

How hard was the concrete?

There is no steel or reinforcing bar in the concrete anywhere in or on the canal. The concrete is about an 8 sack mixture, but not actually known.  It is very hard.  The aggregate in the concrete is granite from 1 to 3 inches in diameter.  The surface of the concrete is very rough.  The concrete is so hardLocks under construction  that any ship that hits or bumps the concrete anywhere comes out the loser.  At left, the locks under construction, in 1910. The partly-constructed middle wall is shown here; the large pipe near the bottom is the culvert used to carry water into the locks. The man standing below and right of it illustrates the scale.  Battleships fit pretty tightly in the locks and they tend to bounce off one sidewall and then across and bounce off the opposite wall.  The battleship will lose its paint where it hits the chamber wall, but the chamber wall is not damaged by the hit.

If the ship does not bounce off the wall and is dragged along the wall, the intense pressure will scrape the paint from the sides of the battleship.  This results in a wide black line about half way between the water line and the main deck. You can see this black line in the video of the Iowa in transit. There will be another line on the other side of the ship.  At this same time there can be a cloud of concrete dust, which looks like smoke, come up between the ship and the chamber wall.

The chamber walls are very rough, as a lot of the granite aggregate is sticking out from the surface of the chamber wall, and it is very hard.  The carriers that used to go through, before the angled flight deck, overhung the sides of the chamber walls by about 2 feet and were much worse about bouncing and hitting the chamber walls that the battleships.

Neither the battleships nor the carriers drag along the sides of the chamber walls more than a few feet at a time.  They hit the walls and bounce off.

About the gates and motors

The gates of each lock are several feet thick and float so their weight is not supported by hinges alone. A 25HP motor operates each half of the gate and when the gate is closed it still has an angle where the gates meet in the middle. Locks at Panama CanalThis angle faces into the higher water which then uses the weight of the water to keep the gates closed.

The gates facing the sea have waves to contend with and the waves can cause the gates to stall when opening and closing. This also stalls the 25HP motor trying to open or close the gate. The original electrical installation was 220 volt 25 cycle. All of the motors were made by GE and had mica insulation around the windings.

Battleship in Panama CanalThese motors were open drip or splash proof configuration but the windings and mica would absorb moisture from the atmosphere. When the motor stalled out, current flow went way up, the motor would get very hot and the moisture would boil out of the windings. It looked like lots of smoke, instead of the steam it actually was.  As the mica did not burn up and let the copper windings short out to each other or the case it was very rare that any motor on the canal actually burned up.

In the 1965 conversion program the canal converted from 220 volt 25 cycle to 440 volt 60 cycle. All electric motors were replaced as well as the electrical switchgear.  Since the conversion, the 440 volt 60 cycle equipment constantly blows up, electric motors burn up often and the electricians are very busy.

About the safety chain

There used to be a heavy chain to prevent a ship from running into the gates during a lockage.  The chain stayed on the bottom of the chamber until a ship was being positioned in the lock.  Then the chain was raised in front of the ship to prevent it from going too far forward and hitting the gates.  There was never a time that a ship even hit the chain, so it was eventually removed, sometime during the 1970's.   

About the wood boring insects

wood boring insect Panama CanalThe locks were overhauled every 2 years and repaired.  The gates used wood for the seal to hold water and provide a sort of bumper between the gates when closing.   The wood was native to the area and is called LIGNUM VIDA.  This wood is so hard that you have to cut it with a hacksaw.  This wood, replaced in the 2 year overhaul, would have holes in it from a bore that ate the wood.  The bore left holes throughout the wood about the size of your little finger.   The bore must have been really tough to live underwater and eat wood that you had to cut with a hacksaw.

Are we out of water yet?

To make one lockage, or transit through the canal, requires 52 million gallons of water. The Panama Canal Company felt that about 60 lockages per day would be about the maximum that could be handled on a daily basis. More that this might, in some years, cause the canal to run short of water. The normal lockages, up until the latter 1980’s and early 90’s, were about 40 per day. There have only been a couple of years when running short of water was even considered.

The first problem is that as the city of Panama got larger, needed more water and was allowed to tap into the Madden Dam Lake.   In the first year they were allowed to take too much water and the lake reached very low levels before the use was restricted.

The second problem is the cutting of the rain forest, which is reducing the rainfall.  If this continues, and everyone believes that it will, it will be the major factor in reducing the amount of available water. There does not seem to be any way to stop this and the Panama Canal Company has known this since the 1970’s. This will seriously reduce the number of Lockages as time goes by.