This is so cool. As discussed in a forum thread on iWindsurf, this easy to tie windsurfing downhaul knot allows you to use your mast foot (or whatever else is handy) as a downhaul handle, and when you are done, the knot just disappears...no untieing necessary. Here are two videos showing different ways to tie it. I prefer the Ezzy version. Took me 30 seconds to figure out.
I like using a cleat (which I have in the van) and even a crank if I'm fine tuning a big sail, but once I'm on the beach at The Bowl I don't want to be walking back to the cars to get the cleat (nor do I want to carry it on the water, or leave it on the beach.) Check these out (and thanks to noshuzbluz and philodog for posting them in iWindsurf):