Half ropes range from about 7.9mm to 9mm diameter, are lightweight and most of the time dry-treated. That’s why they are mainly used for ice climbing, alpine climbing or mountaineering.
Half ropes are engineered to be used in pairs. On the one hand, can be clipped together in the belays to create higher safety especially in sharp edged environment. On the other hand, they can be used with half rope climbing technique. In this technique, half ropes will be clipped alternately into the belays to reduce drag and create higher redundancy. By tying both ends together at the end of the route, the full length of the rope is available for rappelling. An additional advantage of half ropes is their possible use as a single strand in top rope situations. This can for example be useful in three-people rope teams with two followers.
Half ropes are tested in a single strand according to the UIAA standard standard, which references EN 892 with a test mass of 121lbs (55kg). They need to withstand a minimum of 5 falls and the maximum impact force must not exceed 1,798lbs (8kN). The lower mass is used because it is assumed that half ropes normally share the load between both strands.
