This is for people who don’t know how locks work. Everyone else can ignore the post and come back tomorrow.
If you want to go up a lock that is full, the first thing to do is make sure no-one is approaching from the top and wants to come down. If they are, you must wait for them to come through, so you aren’t emptying a lock and wasting water for just one boat (yours.)
2/ Open the paddles (shutters) in each of the gates at the bottom of the lock, by winding up the mechanism (huge heavy cog thingy) at the side. You can just about see Dave doing this on this picture, and the water churning out.
3/ When the lock has emptied and the water levels on both sides of the bottom gate are the same height, open the lock gates. Then close the paddles in these bottom gates.
4/ Sail in.
5/ Close the gates behind you, and open the paddles in the top gate. You can see Dave winding the cog with a windlass (below).
6/ Here he is opening the paddle on the right.
7/ The water in the lock begins to churn and your level begins to rise as the water comes through the opened paddles in the top gate.
8/ Now the water levels each side are just about equal in height.
9/ Open the top gates when you can, by leaning on the end of the beam.
10/ The gate opens.
11/ Sail out the top.
12/ Close the top paddles, and shut the gates.
13/ Sail away.
14/ Don’t forget to wait for your glamorous assistant.