Figure 8 Descent Device (Moved from Rant & Rave)

Q

Qtip

Can you clear something up for me, what are the advantages of using a figure of eight to descend instead of a munters hitch. It can,t be wieght, an 8 requires 2 items of kit, the 8 itself and an attachment crabiner, while a munters only requires a HMS carabiner. What am i missing.
 
Figure 8 Descent Device

Theoretically a Muenter creates more rope wear. Practically speaking a Muenter will allow control of more weight than an eight.... but if you drop the tail on a Muenter you are in a world of hurt. If you drop the tail on an eight you have made a grave mistake but you will not go into complete freefall. Personally I don't work on trees with extreme heights from ground to canopy so I usually work the tree and descend on my hitch.
 
Figure 8 Descent Device

I use a munter almost all the time, not that I descend in that manner all that often.

I notice that the munter seems to clean off some of the fuzzies on my rope. Both the 8 and the munter are easily belayed from below.
 
Figure 8 Descent Device

I used to think that too, but I soon found that an 8 is not effectively belayed from below. By effective I mean stopping a descent.

This I know from training situations teaching the footlock. Once a climber had switched over to descent mode on a winged 8, whilst I was holding the ropes as a back up. He asked if he was secure and i said yes, even if he let go, I had him. He had experience in mountain rescue, and suggested that might not be effective.

So we tried it.

It wasn't effective.

It takes the climber to stop their own descent.

This seems weight dependent, as on lighter climbers it was effective.

I didn't try the muenter this way. I suspect this would be effective due to the friction of rope on rope.
 
Figure 8 Descent Device

An 8 will stop the fall on a bottom belay. If you take tension at the rite angle it will stop you cold. We teach this in Rescue. One of the confidence builders is to put somebody through a hole in the repel tower and habe them place their hands on their helmet. We snap slack into their system and they drop. We stop them from the bottom belay and see if they can handle not gripping the line. You have to belay properly with an 8. Place the line below your bum and sit back on it and I know you'll stop even the biggest climber.
 
Re: Treemotion mods

This is an awesome thread! I love seeing what everyone is doing to their treemotions.

Laz, I think there might have been something else at play. I can't envision why it would matter where the pull was coming from.

I've used bottom belays on 8s effectively in the past. I've not experienced what you're talking about.

love
nick
 
Re: Treemotion mods

Its really quite simple. The rope doesn't run through the 8, the 8 slides down the rope. Pulling on the rope from an angle might make an angle that makes that harder to run.

The point is, some training programmes/advice state that holding a doubled footlock line below a climber will stop a descent. That is not true.

Sorry you can't believe me. Hope it doesn't lead to something serious.
 
Re: Treemotion mods

arborcare1 and Nick,

I believe you guys are talking about an 8 attached to the belayer's harness. Laz is talking about a climber descending a line on an 8.
 
Re: Treemotion mods

Laz, can you clarify? From your most recent post, it seems you are talking about an 8 that slides down the rope with the climber. Are you talking about an 8 anchored at the top?

love
nick
 
Re: Treemotion mods

Nick,

Think of this...the climber is using an eight for a self belay rappel, attached to their harness. A backup belayer on the ground grabs hold of the rope to stop the descent.
 
Re: Treemotion mods

[ QUOTE ]
Nick,

Think of this...the climber is using an eight for a self belay rappel, attached to their harness. A backup belayer on the ground grabs hold of the rope to stop the descent.

[/ QUOTE ]

Thats what I'm talking about Tom........apart from the 'stop the descent' part
tongue.gif
 
Re: Treemotion mods

Tom, I understand that. I use that technique occasionally. Laz is arguing that it doesn't work. I say it does. It doesn't matter if the pull comes from up there or down here. I think there may've been something else at play when Laz was having probs using the pull from below to slow/stop the climber.

love
nick
 
Re: Treemotion mods

[ QUOTE ]
I use that technique occasionally. Laz is arguing that it doesn't work. I say it does.

[/ QUOTE ]


Well, I just don't want anyone to get injured unecessarily thinking they are backed up when, fundamentally, they are not.

Nick, in the past as a seasoned, trained, qualified and regulated instructor, i can tell you I've had to back up more footlock descents for climbers in this way than I care to try and remember. I think any wise person who is sure to have influence, should bear in mind what I'm saying.

Now, I'm not sure why. Seems the only thing stopping the eight from running is friction caused by rope turns through the device, weight of line below the 8 and additional force on that line to over-come the weight attached to the 8. I'm sure an engineer could run the math. A heavy climber can easily overcome that. I know, because I've experienced it more than once.

The point is, it may appear to work for some, but its not a fundamentally 'safe' back up technique. I just felt a responsibility to report what I have experienced. Variables about friction of rope types, distance off the ground/weight of rope etc. just prove the point that, fundamentally, it is not a sound 'back-up' technique.

Discounting a heads up safety issue out of hand, just because you haven't personally experienced it isn't my approach to pro-active accident avoidance - and I have been responsible for the professional safety of hundreds into thousands of persons. I'd like to think thats worth bearing in mind, before the next time anyone is responsible for using this technique.
 
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