A static rope is a type of rope that is not designed to stretch when placed under load. This contrasts with dynamic rope, which is designed to be stretchy and flexible under pressure. Static ropes consist of a core and a sheath. The core mainly functions for weight support, and is made up of individual strands, while the sheath holds said strands together and shields the rope from influences like mechanical wear, chemicals, heat and the like.
The strongest materials used for static rope include nylon, polyester and other synthetic materials. Common types of static rope construction are braid-on-braid, or double braid, and kernmantle. Braid-on-braid rope is constructed with both a braided core and a braided sheath. The core and sheath may or may not be made of the same material. Often, the core material is chosen based on strength, while the sheath is chosen for abrasion resistance. Braid-on-braid rope is very strong. Kernmantle is rope constructed with its interior core (the kern) protected by a woven exterior sheath (the mantle). Its name is derived from the German kern and mantle, which mean core and jacket, respectively.
Kernmantle is designed to optimize strength, durability and flexibility through the core, which provides tensile strength, and the sheath, which provides protection to the core from abrasion. The sheath also determines how easy the rope is to hold, to tie knots in and other handling properties.
The rope’s characteristics may be altered to emphasize one strength over the other, depending on the activity for which the rope is made. Static kernmantle, unlike dynamic kernmantle, is made of untwisted core fibers a tight braid, which makes it stiffer as well as less stretchy.
Static rope has a wide variety of applications, for instance in caving, canyoneering and fire rescue operations. While this rope does have some applications in climbing, it is never used as the rope for lead climbing, because it would break a fall too abruptly and possibly lead to injury. On the other hand, abseiling, also called rappelling, which is a descent technique used on dangerous cliff sides and steep slopes, is best done with static rope. This is because static rope reduces bouncing and makes it easier to ascend the rope.
Static Rope Informational Video