Choosing Suspension Rope
You are going to be lifting your partner in the air. You do NOT want your rope to break while doing so. Keep in mind that, even if a rope is rated for some specific load, that rating is for static (non-moving) loads, and it is the load rating (1) when the rope is new, and has not been subject to wear and tear and (2) when there are no knots in the rope (which reduce the amount the rope can hold).
Also keep in mind that the rope is going to undergo far more strain than the simple weight of your partner, it has to hold your weight while you are lifting your partner. (We say “your weight”. It is really how hard you can pull, the maximum limit in this application being your own weight or you will just pull yourself off the ground…) There are stress factors and safety factors to consider as well which I will add to this article at a later time.
So without getting into the math, here is what you are looking for:
Something that will hold 5 times your weight with a single strand
Something with good friction (not a slippery rope)
Many riggers recommend 8mm (5/16″) for suspension lines. They may tie their partner with 6mm and then suspend them with 8mm. That said, many riggers do also suspend with with 6mm (1.4″) as well, as long as it meets the strength requirements.
If you go with natural fiber, most riggers recommend sticking with hemp as it is stronger then jute or sisal, all else being equal.
You can compare the strength qualities of many different types of rope at Langman’s great site (Polyester, Hempex, Hemp), but it is very important to understand that any strength ratings are under pristine laboratory conditions only, and are not guarantees when in practical use. Once the rope has been under use for some time and some of the internal bits have shifted around, loosened, perhaps some of the internal fibers have broken, any rated strength is right out the window. Rope strength can even be impacted by the knots you choose (famously it is said that having an overhand knot in a length of rope reduces the strain that rope can withstand by 50%). So the point is, buy strong rope, but don’t rely on the rated strength like we do for metal components.
My affiliate Twisted Monk. offers Polyester (POSH) and Hemp, and the links to the left will take you there if you want some (I get a small percentage of the proceeds). But TM does not offer Hempex at the moment, so that link will take you to Langman’s (I don’t have an affiliate relationship with them).
The primary reason I created an affiliation with TwistedMonk was because of their guarantee. If you have to cut your rope in an emergency, they will replace it–free! There are, of course, some provisos and limitations, but this is still an amazing commitment to safety in our community.