How A Lock Works

How A Lock Works. . , Instead of following the slope of the land like rivers and streams, a canal periodically takes a vertical step between long stretches of flat water. Locks were constructed at each vertical step to accomplish moving barges up and down each of the long stretches of flat waterway. The vertical step at this lock is 8 feet. While the lock's hand-operated mitered gates were simple in concept, they required close attention and experience to operate., As a boatman approached a lock, he would sound an alarm half to a quarter of a mile away, alerting the locktender. Entering the lock was the most demanding part of canalling. Canal boats were usually designed to fill the lock as much as possible. Thus, a boat would enter the lock with only inches to spare. If the helmsman allowed the boat to hit the lock walls, he could damage the lock walls or sink the boat. Nevertheless, the boat had to be moving fast enough to go all the way into the lock, yet it still had to before hitting the gate at the other end of the lock. Crashes of this sort were a major cause of damage to the canal, as boatmen would often race each other to get to the lock first., As the boat entered the lock, a crew member jumped ashore and wrapped a rope around a snubbing post anchored next to the lock. Working the snubbing post took a steady hand. If the rope was too tight, the boat would crash into the side of the lock, or the post would snap, sending the boat into the gate at the far end. Too loose and the boat crashed into the gate as well., Once the boat was snubbed into the lock, the locking process could begin. Generally, the whole process of locking a boat through the gates took about 10 minutes., [Sidebar:] , Locking Through Southbound , Sluice valves or wickets on the upper gate are opened and water in the lock is raised to that of the level of the upstream canal. The upper gates are opened and a boat enters the lock ❶. The upper gates and their sluice valves are closed. Sluice valves in the lower gates are opened, allowing water to empty from the lock ❷. The boat is lowered slowly as the water in the lock drops to the level of the downstream canal. At this point the lower gate is opened and the boat proceeds forward joining the lower level of the canal ❸.