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Last night I had a nightmare that I was 5 pitches off the ground and it started to pour rain. When I woke up I realized I have no idea how to deal with this.

Asking around, everyone says two things:

  1. Don't get caught in this situation. Plan better than that.
  2. Rappel down.

In reality, I do plan better than this. But I believe in being prepared. How do you rappel in the rain? What are the challenges? I assume the problem is that the rope is mad slippery. Is that the only problem? How do you deal with that?

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Even when you plan well, surprises happen. +1 –  Don Branson Jan 30 '13 at 0:17

3 Answers 3

up vote 11 down vote accepted

Disclaimer - I should mention that my answer only applies in the context of the original question. I'm discussing my experience rappeling in a rock climbing context, using a dynamic single or half rope, a "stich-plate" or tubular belay device, and an autoblock backup (not a prussik). I can't speak to rappeling in caving (where the gear would be different) or in rescue situations (where you'd be rappeling with the weight of 2 or more people)

Actually, rappelling down a wet rope is about the same. Its just that everything else in climbing becomes more dangerous when its raining. :)

I live on the east coast of the US, and we get rain pretty frequently. There's about a 30% chance of scattered thunderstorms nearly every day, and rain is just a fact of life. I get rained off a route maybe once a year.

While I can't say I enjoy it, actually rappelling down a known rappel route in the rain isn't all that bad, especially if you can stay tied into a rope system the whole time (i.e, you don't have to scramble unroped along a ledge to get to a rappel anchor).

The rope dynamics don't seem to change all that significantly. I always rappel with a regular tubular belay device and an auto-block backup, and I usually rappel with the device in "high friction" mode. (note - I also use a 9.8mm or thicker rope) I would think that the rope would get slipper-ier, but it seems like the ropes get thicker and heavier when they're wet, so maybe that counteracts it some (my rope is supposedly "dry treated", but gets fatter anyway).

What is more dangerous

  • Rock becomes slippery - scrambling and climbing are more precarious. Lichen that might otherwise be dry become moist and slick.
  • Cams might become unreliable. This may just be an incorrect anecdote, but I've heard from other climbers that cams (which rely on friction to grip the rock) can't be counted on
  • Some kinds of sandstone (esp desert sandstone) becomes fragile when its wet.
  • dynamic ropes lose some of their elasticity, so lead falls become more hazardous.
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+1 -- Since you may have experience with this do new ropes (which are slicker and have fresher dry treatment) become more slippery than older ropes? That would be my primary concern, having not yet had to rappel in the rain. –  Mr.Wizard Jan 30 '13 at 2:29
    
New ropes are a little slicker, but I can't say I've noticed it affecting belaying or rappelling... I've never actually gotten rained on in the first month or so of a new rope... do you rappel with an "autoblock"? If you did, you could just put one or two extra wraps on your autoblock, and get more friction that way. Also, if you use a product like an ATC Guide or a Reverso3, you could put the device in "high friction mode" for rappelling, if you were worried about friction. At least, that's what I do. –  DavidR Jan 30 '13 at 2:39
    
Thanks David. I'm not personally concerned about it as I am confident that I could easily get enough friction. Rather, in the context of the question it sounds like you haven't needed to add friction for rain and that (new rope) would be my only area of concern for advising others. Oh, and I use a Prusik but it seems the autoblock is more popular so I should probably look into that. –  Mr.Wizard Jan 30 '13 at 2:42
    
You could test it yourself, if you're worried. Do you have any place you could rig off a low tree branch, or under a patio? You could rig a wet rope 8' off the ground, and see if its harder to just hold yourself right off the ground. :) –  DavidR Jan 30 '13 at 2:45
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@Mr.Wizard - I can't find any recommendations in climbing literature that you would need to change your rappel setup if the rope is wet, and that also isn't my personal experience. I have seen stray comments that the friction of a rope may change, but nothing that recommends that an individual rappeling down a dynamic rope would need to change behavior. Is there a reference I should read? –  DavidR Jan 30 '13 at 14:09

Disclaimer: I have never rappelled in the rain.

Basic requirement

As with any rappel problem a basic requirement is to have enough friction in the system, and preferably a way to go hands-free. As always this should be tested and not simply assumed. I don't think that anyone can tell you exactly what will produce the proper amount of friction without further qualification (rope, rope age, body weight, length of rappel, etc.)

Remember that the control will be less at the bottom of the rope as you will not have the weight of the hanging rope assisting in braking.

Though a wet rope is quantitatively weaker its strength returns to normal when it is thoroughly dried, therefore you should be able to test whatever system you choose without significant expense.

Generating friction

It will help to have an understanding of friction in rope systems. Here is a good reference:
The Mechanics of Friction in Rope Rescue -- Stephen W. Attaway, Ph.D.

Ways to add friction to your rappel system:

  • If you are using a rappel rack add more bars.

  • Create a redirect that adds a bend or two to the rope.

  • Extend the rappel device and pass the brake end through a second device or Munter hitch.

  • Use a Double Munter hitch. This provides a great deal of friction, is always at hand (assuming you have an HMS 'biner) and does not twist the rope in the way that a simple Munter does. It should be excellent as an "oh sh*t" slippery-rappel method. (But as always you must test it yourself.)

With any of these methods you can add a Prusik backup below the device(s). While there is less friction when wet these hitches still work according to testing. Once again you must make sure your particular cord and rope work together.

Additional resources

As far as a source of information consider that cavers and canyoneers routinely rappel on wet rope, though usually not dynamic climbing rope. These people can likely provide good instruction though they may use equipment you are unfamiliar with.

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An example of a redirect: alpineinstitute.blogspot.com/2010/07/… –  Mr.Wizard Jan 30 '13 at 2:07

I'm from the UK and have (therefore) rappelled in the rain lots ;-)

The actual mechanics aren't that different.

Being sprayed in the face with the wet grit that your device is squeegeeing out of your rope is one of the hazards - very unpleasant but not actually dangerous. Rather more serious might be that your wet rope - unlike your dry rope - is now a seventy metre lightning conductor, so you might want to consider whether rappelling in a thunderstorm is preferable to finding somewhere to sit tight and get wet & cold. Not obvious which would be the lesser evil.

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Ah! Thanks for the first-hand experience. I live (and climb) in Northern California on the coast, and the weather is a lot like England here. It rains like 100 days per year. I hadn't considered the lightning rod effect. –  theJollySin Jul 8 '13 at 15:18

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