Rappelling in the Rain

Question

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?

Answer 1

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.

Answer 2

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.

Answer 3

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.

Answer 4

Having rappelled in waterfalls while canyoneering I can honestly say it's not as scary as it sounds. The rope can get more slippery, but the key is keeping a firm grip. I canyoneer without sticky canyoneering shoes (because they're expensive and I'm cheap) and I slip and fall all the time while getting over the edge of a waterfall or while rappelling down a particularly slippery part. However, I never fall into an uncontrolled descent while doing this because my brake hand NEVER leaves the rope. If you fall, you grab the rope tight, stop your rappel, recompose yourself and start again.

As Mr. Wizard mentioned, adding friction will help you control your speed. You can do this simply by holding the rope around the side of your leg instead of off to the side of you. Any curves you can add to the rope will add friction.

It's also a good idea to invest in a device that allows you to add friction while you rappel specifically for situations like this where the base friction of your device may change based on other factors. The CRITR2, SQWUREL and ATS are all great devices to look into that allow you to add friction while rappelling. That way if you start off and feel like you're going to fast, you can always add more friction to slow yourself down.

You can check out the gear I mentioned here: http://www.store.canyoneeringusa.com/component/rokecwid/?Itemid=108#!/Rappel-Devices/c/2490786/offset=0&sort=normal

Keep in mind those are just a few well known canyoneering descenders, there's many more. If you visit the shop you can see the difference in which ones allow you to easily add friction (CRITR2, SQWUREL, ATS) and which don't (ATC, Figure 8).