Heat Generated During Rappel

[Iceaxe]

Last week I did a 300' free hanging rappel and was really hauling butt..... when I reached to bottom of the rappel my rappel device was extremely hot. You couldn't even touch the device or carabiner for several minutes without getting a bad burn.

So my question is.... can you generate enough heat, while rappelling, to melt or damage the rope?

[ibenick]

I have practically no experience canyoneering but I've done quite a bit of rappelling and I have most definitely made the outside of my rope crispier from the friction heat.

[DOSS]

Some devices seem to make more heat than others.. I know that on a 100foot rap the petzl stop will glaze the last 15 feet of my rope pretty bad :(

[Iceaxe]

A rappel device with a large volume will dissipate the energy (heat) better than a small one....

My deal was I flew down the first 200' of rope being a show-off.... I pretty much let the rope run free.... I could feel massive heat radiating from my rappel device (ATC-XP), at which point I was afraid to stop outta fear the device could burn through the rope.

Now I'm curious if you could actually generate enough heat to burn through the rope? Or is your typical glazing the most you have to fear?

[Scott Card]

Gotta tell you what I would fear the most would be the landing after "hauling butt" down a 300 foot rap. I have no experience with glazed rope.

[Iceaxe]

Gotta tell you what I would fear the most would be the landing after "hauling butt".

Then you should love this one.... 876' in 40 seconds!

[Don]

Gotta tell you what I would fear the most would be the landing after "hauling butt" down a 300 foot rap. I have no experience with glazed rope.

+1

[denaliguide]

you see how fast he unclipped?

according to wikipedia nylon melts somewhere between 374 and 663 deg F. even on the low end, that's pretty hot. not sure your rappel device could get that hot without glowing red. you certainly aren't going to be handling it barehanded. that being said, i think repeated exposure to high temp, fast rappels is detrimental to the life of the rope. not sure what the difference in melting point between static vs. dynamic is.

i have been climbing 30 years and 3 things scare me. rappelling, watching others rappell and watching others hollywood rappel. i have taught many people to rappell, from the classic dulfersitz, swiss seat and biner, to a variety of devices. i also rarely wear gloves. when i learned, way back when dirt was first invented, the way we determined we were going to fast, was if our hand was getting hot. old school, baby!

i also have a difficult time when i hear people just going out to rappel. ie sport rappellers. i understand the need to rappel in the course of climbing, canyoneering and caving, but have never looked at it as a sport in it's own right. to me, something is just wrong about walking up the backside to do laps rappelling the cliff.

there are just too many examples of mistakes made on rappell, which have lead to death, for me to do it for fun. i'll walk off the backside. but to each his own.

[Brian in SLC]

^^^^

Bingo. Ditto for me too!

[trackrunner]

Shane there is a similar thread over on the ACA forums about this with real geek data. In theory someone stated you could get a device over 400F while rappelling but they were using a blow torch to heat the device. Heat up a device hot enough with a blow torch and sure could burn through a rope. Is a blow torch the same as rappelling fast?

even a video was posted where they used a rental car @ 30 mph pulling a rope through an ATC and generated heat under 200F on a 65 F day. guys in the video thought you get the device in the mid 200F on a hot dry day over 100F

http://canyoneering.net/forums/showthread.php?t=2773

use enough friction, more biners, two devices, z rig, etc, and rappel slow and smooth shouldn't be an issue. granted I probably don't know what I'm writing about . . .

[qedcook]

I read a bit about this a while ago. The rap devices are designed to dissipate heat throughout the device if the device's point of braking gets too hot. I've never heard of a rap device melting all the way through a rope but i know that stopping for more than a few of seconds when the rap device is extremely hot can damage and weaken a rope. That's why I always go at a slow, even pace down big rappels, no flying fast so the device doesn't overheats and no long stops so the rope lasts longer.

[ratagonia]

... but i know that stopping for more than a few of seconds when the rap device is extremely hot can damage and weaken a rope.

How do you know this?

I mean, do you have a source with some scientific backing? Or is it just a popularly held superstition?

Tom

[qedcook]

By experience, I stopped on a free hanging rap at two different spots to take a couple of pictures. Both spots got a nick in the rope. I noticed it on the second stopping spot and the person rapping after me pointed out the other spot, which was where I had stopped the first time. The rope was getting somewhat close to retirement anyway, so I'm sure that had a lot to do with it. Take it for what it is, anecdotal experience. I can't remember if the paper I read mentioned it or not. I'll have to go back and look.