Figure-eight

The figure-eight is a stopper knot. It prevents a rope from slipping back through a hole.

Think of the figure-eight as safety precaution. Use it when you have finished rigging a line so the line doesn't un-rig itself if you lose control of it. A figure-eight can also keep a line from slipping through your hands.

Never use the simpler overhand knot in place of a figure-eight. Once an overhand knot pulls tight, it's nearly impossible to untie.

The main sheet should always have a figure-eight in the end of it, and so should the main and jib halyards. When you start sailing with a jib in level 2, tie figure-eights in the ends of the jib sheets once they are rigged. And when you start sailing with a spinnaker, the spinnaker sheets get figure-eights as well.

You can "lock" a figure eight by pulling the knot toward you, which will keep it from shaking loose.