Have you ever wondered how a simple lock could be so unique? Lock 9 stands as a testament to ingenuity. It is nestled within the Seven Locks, a closely spaced series of locks along the Chesapeake and Ohio Canal.
Lock 9 is not just any lock. It is situated at Mile 8.7 on the C&O Canal towpath. Lock 10 is within sight providing a convenient parking area.
What makes Lock 9 so special? It is one of the few locks with an upstream drop gate. Most locks use miter gates. Miter gates feature two doors angled upstream. Water pressure naturally keeps them shut. A drop gate is different. It is a single door. It opens by falling upstream like a tailgate on a pickup truck. Mechanical gears hoist it back into place. The gate rests against notches in the stone. This prevents it from falling downstream.
Why the unusual design? The upstream gate was converted to a drop gate. This happened when the lock was lengthened by ten feet. The change accommodated larger boats. The C&O Canal Company likely wanted to test the drop gate technology. Only a few locks were enlarged and the longer boat concept never fully took off. The downstream end of Lock 9 remained unchanged. The miter gate stayed in place.
Interestingly, Lock 9 was built a little differently than Lock 8, its close neighbor. Lock 8 was the first lock built with red sandstone. Lock 9 primarily used granite. Some Aquia freestone and sandstone were also incorporated.
The C&O Canal relied on 74 lift locks. These locks helped boats navigate the 605-foot elevation change between Georgetown and Cumberland. Think of the C&O Canal as a staircase. Canal boats traveled flat sections and used locks to step up or down about eight feet.
Entering a lock was the most demanding part of canalling. Lock 9 with its drop gates aimed to speed up the process. Locks 8 through 14 are known as the Seven Locks. These seven locks are all located closely together over a 1.25-mile stretch.
So next time you are near Lock 9 remember its unique drop gate. Consider the ingenuity of canal engineers. Lock 9 stands as a reminder of the C&O Canal’s innovative past.