Kernmantle rope is the lifeblood of vertical rescue and fall protection. It consists of a tough braided outer sheath (the mantle) protecting a bundle of parallel, load-bearing fibers in the center (the kern). When you finish using a rope to lower a piece of equipment or secure a load, how you put it away directly dictates how long that rope will live. The absolute worst thing you can do to a kernmantle rope is tie it in a simple overhand knot or a slip knot to keep it tidy.
When you tie a knot in a kernmantle rope and pull it tight, the outer sheath constricts, but the inner core bunches up inside the knot. This creates severe internal friction between the core fibers and the sheath. Over time, as the rope sits in storage with a knot in it, or if that knot is repeatedly pulled tight under load, the inner core fibers will actually saw through each other. When you eventually untie the rope and run your fingers down it, you will feel a soft, mushy spot where the core has been permanently damaged. That rope is now compromised, even if the outside looks perfectly fine.
Safety ropes must be coiled, not knotted. The industry standard method is the "butterfly coil" or a proper mountaineeer's coil. When you coil the rope, you must ensure that every loop naturally twists in the exact direction the rope was manufactured. If you force the rope to lay flat in a coil by adding artificial twists, you introduce "hockles" or kinks into the line. A hockled rope has uneven tension across its internal fibers. If you put a dynamic shock load on a hockled rope, it will vibrate violently and can physically rip itself apart because the load isn't distributed evenly across the core.
Once coiled correctly, secure the middle of the rope with a piece of light cordage or a specialized rope strap-never use the heavy working end of the rope to tie off the coil. And never store a rope on a concrete floor. Concrete is highly alkaline and draws moisture. The alkalinity will literally eat away at the nylon or polyester fibers over time, degrading the rope from the outside in. Coiled ropes must be hung on a peg or stored in a rope bag, completely off the ground and out of direct sunlight.
