Descenders & Belay Devices
Climbing descenders & rappel devices are indispensable for mountain climbers, alpinists, canyoners, rescue teams, etc. When choosing a descender, make sure the method of operation, rope compatibility, quality of construction, weight and size are all suitable for your task. Remember, YOU are the safety device. These are just tools!
TYPES OF DESCENDERS
Tubular Belays
Simple, lightweight devices with a tube-like shape and slots for one or two ropes. They rely on friction created by bending the rope around the device. Some have grooves or teeth to increase friction. Sometimes called ATC's, after Black Diamond's original "Air Traffic Controller" device.
Uses: Versatile for belaying a leader, top-roping, and rappelling. Popular for general climbing.
Advantages: Lightweight, inexpensive and easy to use, tubular belays work with a wide range of rope diameters and don't twist the rope much.
Disadvantages: Tubular belays don't offer assisted braking. They also require a good belayer technique, but that is true of all belays.
Examples: Black Diamond ATC, Singing Rock Buddy, Kong Chuy, etc.
Assisted-Braking Belays
Assisted belays have a mechanism that assists in braking the rope in case of a fall. Some use a camming action, while others use the geometry of the device and carabiner to pinch the rope.
Uses: Primarily for belaying, especially sport climbing and indoor climbing where falls are more frequent. Some models can be used for single-rope rappelling.
Advantages: Provide an extra margin of safety by helping to lock off the rope during a fall, can make belaying easier, especially with a heavier climber.
Disadvantages: Can be more expensive and heavier than tubular devices, may have specific rope diameter requirements, some are not ideal for rappelling with two ropes.
Examples: Petzl Grigri, Kong Indy, Beal Birdie, etc.
Manual / Friction Belays (Figure 8, etc)
Rope is threaded through the device in a specific way to create friction for rappelling.
Uses: Primarily for rappelling. Some models can be used for belaying, but they are less popular for this due to their tendency to twist the rope. Common in canyoneering, search and rescue.
Advantages: Good for rappelling, can handle a wide range of rope diameters, dissipate heat well during long rappels.
Disadvantages: Can twist the rope significantly, not the best choice for belaying, require careful threading.
Examples: Kong BIG 8 and Oka, Singing Rock Buddy, etc.
Brake Bar Racks
Consist of a frame with multiple metal bars over which the rope is threaded. The number of bars used can be adjusted to control friction.
Uses: Primarily for rappelling, especially in caving and industrial applications where long rappels and heavy loads are common.
Advantages: Offer a wide range of friction control by adding or removing bars, good for long rappels as they dissipate heat well.
Disadvantages: Can be bulky and heavier than other devices, more complex to use, not typically used for belaying.
Examples: Kong Rackong, SMC Micro Rappel Rack, NFPA, etc.
Bobbins
Feature one or two grooved pulleys (bobbins) that the rope passes over. Friction is controlled by how the rope is wrapped around the bobbins. The Petzl Stop has an assisted braking mechanism.
Uses: Primarily used in caving for rappelling. The Petzl Stop is popular due to its ability to stop the descent if the handle is released.
Advantages: Compact, relatively lightweight (except for models with braking features), can be easier to attach and detach from the rope than racks.
Disadvantages: May not offer the same range of friction control as racks, can heat up on very long rappels, the Petzl Stop has a specific rope diameter range.
Examples: Petzl Simple, Stop, etc.
Rescue Descenders
Robust, multi-functional devices designed for technical rescue and rope access work. They often feature self-braking mechanisms, anti-panic functions, and the ability to lower and haul heavy loads.
Uses: Professional rescue, industrial rope access, where safety and control with heavy loads are critical.
Advantages: High safety features, excellent control under load, versatile for lowering and hauling.
Disadvantages: Expensive, heavier and bulkier than recreational devices, often require specialized training.
Examples: Petzl I'D, Maestro, etc.
Mechanical Prusiks
Specialized devices used primarily in tree care. They allow for efficient movement up and down ropes, mimicking the function of a Prusik knot but with easier handling and consistent friction.
Uses: Arboriculture for climbing and positioning in trees.
Advantages: Provide smooth movement, consistent friction, and often have features for easy slack tending.
Disadvantages: Primarily for tree climbing, not typically used for general climbing or rappelling.
Examples: Petzl ZIGZAG, etc.
Individual Evacuation Systems
Compact, pre-rigged systems designed for emergency escape from height. They often include a self-braking descender, rope, and connector.
Uses: Personal escape in situations like working at height or in industrial settings.
Advantages: Ready to use in emergencies, self-braking for safety.
Disadvantages: Limited to their specific purpose, not for general climbing or rappelling.
Examples: Petzl EXO, etc.
SAFETY
A large number of climbing injuries are due to improper belaying and rappelling practice, ie operator error (even in high-profile professional cases). Be sure to get proper education, training and practice with any new device before using it in a real-world situation.