Rappelling can be used on mountains, rock ledges, waterfalls, sea cliffs, natural or manmade towers, buildings or even low-angle slopes that would be dangerous to walk down.
Rappellers use strong nylon or polyester ropes with varying degrees of stretchability, and anchoring materials such as rope or nylon webbing to tie to trees, boulders, rock horns, bolts and/or pitons.
Descent control devices are small metal tools used to create friction and aid a rappeller's brake hand in slowing downward progress.
Multiple carabiners (strong metal links with gates that open and sometimes lock when closed) are connected to anchors and/or decent control devices.
A harness is a necessity in order to stay safely connected into the system.
A double rope rappel means that two strands of rope are hanging from the anchor and running through the device and the rappeller's hand. In a single rope system, the rope is fixed at the anchor and the rappeller descends using only one strand.
Retrievable v.s. non-retrievable rappel site setups are identifed by whether the group can pull the rope and/or anchor down from the bottom.
Australian vs. standard rappelling describes the body position of the rappeller: In Australian rappelling, you face downward; in standard, you come down in a sitting position.
Speed and style while rappelling are largely dependent on the type of descent control device being used. Figure-eight plates are notoriously very slick and rappel racks have adjustable bars that slide to increase or decrease the amount of friction. If used correctly, these devices can be quite smooth. Less-smooth devices in tube- and simple plate-like forms have more friction, giving the rappeller more control and ability to slow down.
Auto-locking devices have a camming mechanism that will pinch and lock off the rope under body weight. These are not the best tools for rappeling because they require two experiencd hands to control while descending. The Munter Hitch is a movable hitch in the rope used in conjunction with a locking carabiner. It has an incredible amount of holding power and is a great backup in the event of dropping a device, but tends to make the rope squirrely if not held in the proper brake position. Threading the rope through carabiners to create friction is another backup trick.
Before the discovery of the Munter Hitch and the manufacture of metal descent control devices, mountaineers used to wrap the rope around their bodies to create friction and aid descent.
For mountain and rock climbers, rappelling is simply a means of accessing climbing routes, getting back down or escaping a route. It usually means they are either done climbing and are rappelling as part of the descent or they need to retreat mid-climb for some reason. Rock climbers and mountaineers rarely rappel for fun of it.
In contrast to climbing, rappelling is actually the main focus of caving and canyoneering. Cavers rappel down vertically oriented caves in their adventures and canyoneers drop into canyons in hopes of finding cliffs and waterfalls to negotiate.
Warning & Considerations
Rappelling can be a very dangerous activity if not executed properly. Doing it safely is totally dependent on the strength of the anchor, proper setup of the device or hitch, constant grasp of one's hand(s) on the rope, and the end of the rope being set to proper length or managed by a stopper knot.