All you need to know about ropes for canyoneering. This will cover rope terminology, the different types of ropes used in the sport, and how to protect or prolong its life.
There is a "rule" out in the canyoneering community that says you need to bring 3x the amount of rope of the tallest rappel. This isn't a "rule" per-se, but more of a guideline. There have been many canyons where I have not brought 3x the amount of rope. It's just a lot of weight!
However, bringing at least 2x the amount is considered a best practice. Let's provide an example - if your tallest canyon is 80 feet, then bringing 160 feet should get you okay. It isn't sufficient enough to bring just 1x 100 foot rope, and that's it. What if it got snagged when you were trying to retrieve it? What if you dropped the rope bag on your way to the anchor? What if...? If you didn't have an extra rope, you and your group would be literally stuck for who knows how long. That's not a great predicament to be in! But if you brought another 100 rope, then you could easily rig that one up, rappel down to where the other rope is stuck, get it free, and continue on. In fact, you wouldn't even lose much time over it.
I would suggest bringing two ropes in which lengths are over the tallest rappel length, plus a small 6mm or even 3mm pull-cord as your emergency rope. It's not much extra weight. And this is just the cost of canyoneering to help assure you have redundancy and bring more peace of mind in case things go wrong.
There are some common rope lengths and sizes in Canyoneering that we use.
These are 60, 120, 200 and 310 feet. Most canyons' rappels will be at or under 200 feet in length.
For canyons where the tallest rappel is 30 feet, I'm not going to bring my 200 ft rope (if I have other options). That's where I would bring 60 feet and a back-up rope that a friend would carry.
To those starting off, I would get two rope sizes (if you can spare the cost): either 2x 200-ft ropes, or either a 120-ft rope AND a 200-ft rope.
The minimum in diameter rappelling rope that you should buy is an 8 mm rope. Even then, this rope is designed for intermediate to experts as this rope is skinnier, lighter, and needs more caution and setup to rappel on it. Heavier people (above 190 lbs) will most likely not enjoy this rope as you will need more friction to be added to all of your rappels.
And before long, you will need to be buy a pull-cord. I would suggest a 6 mm 200-foot, static rope which also is in a rope bag (an additional cost).
DO NOT buy a dynamic pull-cord rope. They may be cheaper to buy BUT they make a world of a difference when it comes to retrieving the rope. The dynamic pull-cord will stretch and stretch without budging the rappel rope on top! All of that energy you are exerting, will get absorbed by the stretch! So, that means a lot of people pulling down on the pull-cord may not budge the rope at all!
(Lesson learned a long time ago on a rappel that was 220 ft and we had to hike back to the top to retrieve it).
There are two primary types of ropes: Dynamic & Static.
Dynamic ropes are designed to stretch. This stretchiness is what absorbs the energy in case of a fall. It's primarily made of nylon. Dynamic rope is primarly meant for rock-climbers where falls can be common.
Static ropes are primarily designed for strictly rappelling. That's in fact what canyoneers primarily do! Static ropes are not "weaker" or "less strong" than Dynamic ropes, but rather serve a different purpose. The goal with static ropes is to offer strength while being compact in size. Some canyons require you (or someone who is able!) to carry this rope ALL-DAY. Having been the pack-mule for my group for most of our canyoneering trips, I can indeed say, that having a smaller and lighter rope makes a world of a difference. But the skinnier the rope, the MORE friction you will need to add!
Canyoneers typically use ropes that are either 8mm, 8.3mm, or 9mm rope sizes. Our pull-cord is the only rope that is is 6mm in size or less. You can rappel on 6mm but it is in emergency use only because MUCH more friction is needed to rappel safely done. Please DO NOT rappel on 6mm rope. You or one of your friends will get seriously injured or killed.
You do not need to be washing and cleaning your brand new rope at every rappel. If there is a lot of sand in the rope, a rinsing in a pothole of water would be advisable. Otherwise, all of those grains of sand will be embedded in the rope and as people rappel down, that sand will literally act as a type of saw and wear out your descender/rappel device. Even after one rappel. This is especially true with aluminum devices. Steel descender/rappel devices and carabiners are much more durable when it comes to sand. One steel carabiner, for example, is above $15 and weighs over 0.50 lbs!
If the rope is wet after your trip and is ready to be stored, let it air dry outside (but not in direct sunlight) for about 30-minutes. You do not want to store it wet for long periods of time.
It's good practice to examine your ropes once before a trip. You are specifically looking for "core-shots" or deep cuts on the rope. If it has light "fuzzing", this is considered acceptable as it is formed when a descender device gets hot (while rappelling) and rubs over the rope.