The Timber Hitch
When tying reef lines around the boom, many crews use a bowline. But when you've reefed down in a 50-knot breeze, a bowline welds itself into a tight mass of line that can often be untied only with a knife.
An alternative knot that's guaranteed never to jam is the timber hitch. Rig your reef lines as follows: Take your reef line from its block at the end of the boom up through the reef cringle, then down, through the foot of the sail, around the boom, then around itself before it goes around the boom. From there it's a simple matter of making several loose wraps around the line, as shown in the photo.
When you reef, the load on the line prevents the timber hitch from coming undone, and it can never bind on itself. It should be noted that using a timber hitch for your reef lines won't work on a flat-sided boom-you're stuck using a bowline. If your boom has padeyes onto which to tie the dead end of the reef line, get rid of them. And if your mainsail's foot runs in a groove, ask your sailmaker to put slits or grommets in the sail where the reef lines pass through it.