Lots of people learn how to rappel double-stranded (with two stands of rope running through their descending device). Most climbers use a double-strand rappel when they finish a rock climb. This usually works pretty well on clean vertical climbing routes. Canyoneering, on the other hand, is composed of mixed terrain with obstacles and places to snag the rope. Here are some reasons why a canyoneer might not want to double-strand:

1. Twists and turns in the canyon can force the ropes of a double-stranded rappel to roll over each other and those twists add friction that can make it really hard to retrieve the rope later.
2. Twisted ropes in canyons can’t always be separated as easily.
3. Two twisting ropes are incredibly dangerous if you are rappelling in a waterfall. You do not want the ropes to tangle up while you are tied into them. Aquatic rappels and Class C canyons are done almost exclusively on single-strand rappels.
4. Mechanical ascenders are made to be used on a single rope. If you need to reverse the rappel for any reason (like if your rope is too short) you will have to use a prusik on a double-strand rappel. Prusiks can be slow to deploy and use. You could use mechanical ascenders quickly and efficiently on a single-stranded rappel.
5. Single-Strand rappels lend themselves easily to setting the rope length so that you don’t have to bag more rope than necessary on small nuisance rappels.
6. Rescue scenarios are much easier on single-stranded rappels because you can keep half of the rope at the top of the rappel and use it to help someone in need.
7. Single-strand rappelling is usually the way to go when you tie two ropes together. Since there will be a knot on one side of the rappel, you either need to pass the knot (which is a ton of work and introduces more risk to the maneuver) or you could single-strand rappel and put the knot on the pull side.

If you have decided to try out a single-strand rappel, there are a few nuances to consider. If you are joining us from the climbing world, you are probably used to rappeling double-stranded on 9mm rope. The most popular canyoneering ropes are currently around 8mm so there will be less friction to slow you down. Additionally, there will be even less friction when you are using half the amount of rope by moving from double strand to single strand. This is why there are specific devices made for canyoneering like the Critr3 and Hoodoo that allow you to adjust friction settings. A device like this is essential to your canyoneering kit and we also highly recommend a hands-free backup like an auto-block or VT-prussic and a belayer when rappelling single-strand for the first time. Practice in a controlled environment before heading out to the canyons.