Fenders, as most sailors know, act as bumpers to keep your boat off the dock and prevent its hull from being scratched or chafed by whatever protrudes from the dock, like cement or wood pilings.
Call me a pack rat, but I hate throwing anything away that could still have some use aboard. My husband David uses old line to make ocean plait rugs. I use old jacklines to keep jerry jugs firmly in place on deck and also as hoists when making courtesy flags. So when it came time to buy a new mainsail, I couldn't just throw the old one away.