All lines (ropes) on a boat will unravel and fray at the end unless the line end is treated in some manner. You can try tightly wrapping the end with tape, but tape usually rubs off or quickly disintegrates in working conditions. You can fuse the fibers of synthetic lines (nylon, polypropylene) with a flame, but the result is ugly, harsh on the hands, and often not long lasting. After hundreds of years of good seamanship, the historical method of whipping the line end with twine remains the best method and lasts the longest.
Whipping tightly binds the line’s fibers near the end. Because the line end actually becomes smaller when compressed beneath the whipping, the line will not bind in blocks or other sailboat gear.
All you need is whipping twine (usually a waxed synthetic) and large needle to get started. Whipping is easy to learn if you follow these steps. Shown here is a double-braid line, but whipping works just as well with a standard three-strand twisted line.
Use a needle to pull the free end of the whipping twine through a bit of the line’s outer braid toward the free end of the line being whipped (to the right in this photo).