Wrap the lines around a cleat at the bow and the stern and ensure that a crew member is stationed at each position. Once the boat is secure, turn off the engine and the radar (if you have one). The lock gate behind you will now be closed and after that the opposite gate will be opened. Depending on whether you are going from a lower to a higher level or vice versa, you will experience an inflow or outflow of water. This is where having crew members stationed at the bow and stern becomes crucial.
This is because of two things. The first is that the water level is either rising or falling. Because of this the lines holding the boat secure are either getting very taut or very loose. The crew members have to adjust the lines accordingly otherwise you might be hung out on the wall of the lock or drift into other boats secured there. The second issue is that the rapid movement of water will cause a current to flow. This will move your boat around, thus requiring the crew members to keep it steady. This is also why you need the fenders, because it will protect against any scraping.
Once the water level reaches the desired level, the gates are completely opened. You may then start the engine and after that hand the lines back to the lockmaster or if they are yours, take them in. Thereafter you will have to follow the lockmaster’s directions and exit the lock using caution. Be aware that there may be boats waiting to enter the lock from the other side. When you clear of the lock, you finally take off the fenders and get underway with your journey.