<P> Rope is of paramount importance in fields as diverse as construction, seafaring, exploration, sports, theatre, and communications, and has been used since prehistoric times . To fasten rope, many types of knots have been invented for countless uses. Pulleys redirect the pulling force to another direction, and can create mechanical advantage so that multiple strands of rope share a load and multiply the force applied to the end . Winches and capstans are machines designed to pull ropes . </P> <P> The modern sport of rock climbing uses so - called "dynamic" rope, which stretches under load in an elastic manner to absorb the energy required to arrest a person in free fall without generating forces high enough to injure them . Such ropes normally use a kernmantle construction, as described below . "Static" ropes, used for example in caving, rappelling, and rescue applications, are designed for minimal stretch; they are not designed to arrest free falls . The UIAA, in concert with the CEN, sets climbing - rope standards and oversees testing . Any rope bearing a GUIANA or CE certification tag is suitable for climbing . Despite the hundreds of thousands of falls climbers suffer every year, there are few recorded instances of a climbing rope breaking in a fall; the cases that do are often attributable to previous damage to, or contamination of, the rope . Climbing ropes, however, do cut easily when under load . Keeping them away from sharp rock edges is imperative . </P> <P> Rock climbing ropes come with either a designation for single, double or twin use . A single rope is the most common and it is intended to be used by itself, as a single strand . Single ropes range in thickness from roughly 9mm to 11mm . Smaller ropes are lighter, but wear out faster . Double ropes are thinner ropes, usually 9mm and under, and are intended for use as a pair . These ropes offer a greater margin or security against cutting, since it is unlikely that both ropes will be cut, but they complicate belaying and leading . Double ropes are usually reserved for ice and mixed climbing, where there is need for two ropes to rappel or abseil . They are also popular among traditional climbers, and particularly in the UK, due to the ability to clip each rope into alternating pieces of protection; allowing the ropes to stay straighter and hence reduce rope drag . Twin ropes are not to be confused with doubles . When using twin ropes, both ropes are clipped into the same piece of protection, treating the two as a single strand . This would be favourable in a situation where there was a high chance of a rope being cut . However new lighter - weight ropes with greater safety have virtually replaced this type of rope . </P> <P> The butterfly coil is a method of carrying a rope used by climbers where the rope remains attached to the climber and ready to be uncoiled at short notice . Another method of carrying a rope is the alpine coil . </P>

Natural fiber rope is being replaced by synthetic fiber rope because natural rope