Lift Locks - Boat Elevators

Right Side: Historic Boat Entering a Lock
NPS

Left Side: Modern Boat in a Lift Lock
NPS/E. Cowan

 

What are Lift Locks?

Canal Boat exiting a Lift Lock
NPS/Harpers Ferry Center

Instead of following the slope of the land, a canal periodically takes a vertical step between levels of the flat water. This is accomplished at a series of lift locks, which on the C&O averaged a drop if 8 feet. The operation, though, demanded experience and close attention.

Why are Lift Locks Important?

Lift Locks are important for many reasons. Here are just a few:

• Boats can navagate in both directions on the canal
• Lift Locks created flat water levels, this limited the amount of water current in the canal.
• A single lift lock can raise a boat 8-10 feet at a time. They made climbing over 600 feet of elevation possible for the C&O Canal.

Who was responsible for the Lift Locks?

The Lockkeepers! They were hired by the C&O Canal Company to operate the lift locks they were assigned to.

 

Lift Lock Basics

Everything you need to know about lift locks!

How many Lift Locks are there in the C&O Canal?

There are 74 locks in total! You may say, "But there is a lock named Lock 75!" And that is because Lock 65 doesn't exist. When the canal was consructed they realized that they didn't need to build a Lock 65. The builders found it was too much work to change the name of every lock after 65 in the paperwork.

How long did it take to fill up a Lift Lock?

About 8 to 10 minutes but the record of the fastest time was about 5 minutes.

How do Lift Locks work?

Now that's a big question that requires some context. 

• The first thing you need to know is that the Lift Locks use a lot of water pressure science. Meaning that this lock design uses the fact that water is heavy and wants to go downhill to its advantage. 

• The second thing you need to know the Lift Lock doors also called Lock Gates, when they are closed they are pointed towards higher water aka the higher water pressure.

• The third thing is that a lift lock has two sets of Lock Gates one on either side of the lift lock.

• The last thing you need to know is at the bottom of these Lock Gates are small doors called panels that can be opened and closed by a Lock Key. 

Three-part diagram depicts the process of a canal boat "locking-through
Photo Credit: Artist: Demers, Donald Contacts: Organization: Harpers Ferry Center

Let's begin the locking-through process. 

Say we have a boat that needs to go up to a higher water level. Currently one set of gates holds back the higher water and the other is open to let the boat in. The reason the high water doesn't come crashing through is because the gates are pointed. 

The water pressure pushes on the gates keeping them shut tightly. Try putting your fingertips together tightly in a point and pushing. This is similar to the way pressure keeps the lock gates shut.

Our boat floats into the lock through the open gates and gets tied off at snubbing post to secure the boat in place. Now the back gates are close. The boat is now enclosed in the lock.

The lock keeper uses the special tool called a lock key to turn the small panels at the bottom of the higher water level gates. This lets the water rush in from the bottom filling the lock. 

The water level rises till it matches the higher water level. Now the lockkeeper pulls open the high water doors to let the boat out of the lock.

Are there any Lift Locks at the C&O now?

There are a few operation lift locks in the park. There are some in Georgetown, DC and one at the Great Falls Taven. The lift lock in Williamsport is not operational but is a good model of what one would look like.