Most boaters carry one or more vinyl fenders on-board. Hung over the side, fenders protect the vessel from colliding with a pier or another boat if you are rafted up together. Attaching the fender to the boat is accomplished with a piece of line called a fender sheet, which is usually 7 to 9 feet long. Securing the fender to the line requires a knot. One method is to tie a stopper knot on a fender sheet and then suspend the fender from one of the lifelines on your sailboat.
Lay your palm under the line about 18 inches from the end.
Pass three turns of line around your fingers.
Take the end of the line and pass it between your palm and the turns. Slip your fingers out.
Work out the slack and tighten the rope turns, while working the knot close to the end of the line. Use both hands. You will eventually have a type of stopper knot sometimes referred to as a blood knot. The diamenter of the knot will be nearly 2 inches.
Pass the line through the centre tube in the fender, pulling it all the way through until the stopper knot reaches the end of the fender. The stopper knot will prevent the fender from sliding off.
Clip the adjustable fender hanger onto/around the lifeline.
Slip the free end of the fender sheet through the adjustment clip. Drop the fender over the side.
Pull on the end of the fender sheet until the fender is raised to the height necessary to protect the hull.
The advantage of securing fenders in this fashion is twofold. First, the stopper knot will never pull out or unravel. But if you do need to untie it; it will untie easily. Second, when it's time to shove off from the pier, unclip the fender adjuster from the lifeline and stow it. When you return to the pier, slip it back over the lifeline. Because the clip holds the fender sheet firmly in place, when you redeploy the fender, it will already be at the proper height. This could be doubly handy if you return to your slip after dark.