Auto-Blocks for Efficient Follow-Belaying

Auto-Blocks for Efficient Follow-Belaying
October 13, 2017 Orvel Miskiw

Conventional BD ATC is symmetric and Has No Auto-Block Capability

I recently noticed that many climbers never use auto-blocks for belaying their followers. Even some very experienced climbers seem to be unaware or uncomfortable with using the auto-block capability of their Reverso or BD ATC Guide devices. It occurs to me that in fact this situation may be most prevalent among older or experienced climbers, who keep their tried-and-true techniques and even equipment in spite of recent developments that may make some operations much easier for them.   Younger climbers, who learned and started climbing in an environment of predominantly modern methods, are more likely to find auto-block belaying ‘natural’ rather than a radical change.

An auto-block system can greatly facilitate bringing up your followers on a climb, especially if two or three of them are able to climb at once — as is often practical. Since climbers never move at the same speed, slack in their ropes develops at different times, so the ropes are best taken in separately, rather than both at once or equally. An auto-block brake allows the belayer to take up one rope at a time, then drop it and turn his attention to another rope that’s coming slack as its climber moves up; the auto-block ‘tends’ the dropped belay rope and will lock it automatically if the climber on it slips or falls.

 BD ATC Guide Can Work in Friction Mode for Rappels and Lead Belaying, Has Enhanced Control Friction in Notches, PLUS Has an AutoBlock Mode



Several auto-block devices are available, and without even doing a search I can mention 5 that come to mind right away: the Reverso, Black Diamond ATC Guide, Plaquette, Tibloc, and an old Camp device that I own (featured and below) that has a hinged sliding bar to eliminate the need for an extra carabiner.   All of these serve the purpose of making the belaying of seconds easier, as they allow the rope to run in one direction but lock for the other direction. (Above) BD ATC Guide in AutoBlock Mode: Anchor Crab Through Integral Ring Tilts the Device to Jam Control Ropes in Friction Slots.

Camp Alien Belay/Rappel/ Autoblock Device with Hinged Integral Bar

Camp Alien Brake: Left Rope or Pair would be Loaded in AutoBlock Use; Right Rope or Pair Loaded for Rappelling or Lead Belaying

All except the Tibloc can also be used for lead-belaying and as a rappel brake, but the Tibloc has negligible weight as an extra bit of gear and works with nearly zero friction for taking in rope; however it’s the most difficult to release in case giving slack becomes necessary, so restricted to belaying on sloping climbs (not advisable where a follower might end up hanging on the rope).  Note that even a Prussik is an autoblock and can also be used for belaying if necessary.


Another very important advantage of auto-block belaying is that these devices are best connected directly to an anchor above the belayer and so allow the use of straight-arm and body-weight pulling and feeding of the ropes — a lot easier than the relatively cramped positions typical when belaying off the harness.  For a conscientious belayer, the auto-block method eliminates the struggle  of tending two (or more!) ropes at once — controling both at once in case of a slip, while at the same time taking in the ropes at different rates as the climbers move up at different speeds or stop and go alternately.

Petzl Tibloc Device has teeth in the Trough Behind the Rope; Locks if Left Rope is Pulled; Runs Freely if Right Rope is Pulled, with only the Friction of the Carabiner.

Two Tiblocs for Two Ropes, for AutoBlock Belaying on Slabs

I heartily encourage climbers to learn the full functionality of all their items of equipment; a good start is to read and study the literature that comes with most pieces of hardware like the BD Guide: that fully describes auto-block belaying, which is the primary difference and gives the ATC Guide and other such devices a great overall advantage over the original ATC and similar ‘tube’ rappel/belay devices.

(CAUTION:  The ACC Calgary Section does not recommend unconventional uses for climbing equipment, for example the use of the Tibloc or a prussik for belaying, and advises climbers to attempt such techniques only with their personal discretion, great care, and after reading the manufacturers’ recommendations.  These are mentioned by the author after many years of experience and mainly as examples of alternatives that are workable in some situations.)



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