The boatman would blow his bugle, alerting the lock tender of the incoming boat.
The lock tender opened the gates. Entering was demanding because the boat could hit the walls.
The paddles on the far gate opened using the lever on the gate. This leveled the water.
Now the locking begins. For a boat going south:
Then the lower gates are opened, the mules are harnessed, and the boat continues on its route.