Your boat is a large investment, in terms of both time and money, and fenders are the best way to prevent damage to your boat when tied to a pier, since they stand between your boat's finish and the pier itself. Fenders can be purchased from any boat dealer, but the do-it-yourself boater can quickly and easily make fenders that have a fine nautical appearance ready-made plastic fenders lack.
Lay the line out in an "S" shape.
The fender begins life as a variation on the classic gallows knot (a hangman's noose), but unlike the gallows knot, the first turn is made through the bottom loop rather than around the bottom loop, which will be drawn tight when the fender is completed. The bitter end will be turned through the top loop and drawn tight, as in the gallows knot. An exploded view of the rope work is shown in the image. The length of the fender will be determined by the number of turns around the line. The length of line needed (in feet) is determined by multiplying the desired length of the fender (in feet) by 6.25.
Pass the bitter end through the bottom loop and begin to make turns around the two bights forming the central core. When you have completed the number of turns sufficient for the length of the fender, pass the bitter end through the top loop. Tie a figure-8 knot as close to the top loop as possible.
Draw the top loop tight by pulling on the bottom loop. This will require some serious tugging and patience, but there is no easy way to do it without damaging the finished product.
Pull the bottom loop tight by pulling on the standing part of the line. You'll know when you're pulling on the correct side of the loop, because the loop at the other end of the fender will tighten.
Turn an eye splice in the end of the standing part as close to the top of the fender as possible. Paint the nylon rope to match your hull or a color that will stand out in your deck gear box. You now have a fender with a loop at the top with which to secure the fender to a cleat or fender board. Attention to detail and patience will make these fenders stand out in a marina full of plastic boat bumpers.