The Valdotain Tresse (VT) is a directional friction hitch that’s popular with arborists. Similar to a standard prusik loop, it allows a climber to ascend or descend a fixed rope.
Traditionally, the VT was tied with a length of medium sized cord, such as 7 mm, with a couple of loops tied in each end. To improve this, canyoneering expert Rich Carlson designed an enhanced version he calls the “VT Prusik”, and it’s pretty slick.
Made by Blue Water Ropes, it looks like an extra thick Sterling Hollow Block. It costs about $25. Instead of a single loop, it has a sewn eye at either end. It has a Technora (similar to Kevlar) sheath and a nylon core, and it’s stout - the end-to-end strength is about 20Kn, and basketed it’s about 30 kN. It plays well with a wide range of rope diameters from about 8mm to 11mm. Because of this, you can use it for some creative configurations.
So, what’s cool about the VT prusik?
The main benefit is that you can tie various friction hitches that both grab tight and release easily. This eliminates the two main problems with the traditional prusik knot - cinching down hard on the rope when under load, and then wrestling to release it when you need to.
Let’s look at some ways to use the VT prusik.
There’s lots of fancy knots you could tie with the VT prusik, but you really only need two:
the asymmetric prusik for moving upwards, or hauling anything in an upward direction, like a progress capture.
the Valdotain Tresse aka “VT hitch” for moving downward on the rope, like for a rappel backup.
1) You can make a “asymmetric” prusik, which allows you to move the prusik up the rope much more easily after it’s been weighted. This knot works best in any situation when you need to move UP the rope. (This is also known as a “Schwabisch” hitch.)
(Note: unlike a symmetric prusik, which holds equally well in either direction, an asymmetric prusik like this only holds on the rope when pulled in one direction.)
2) You can tie a VT hitch, which has a few unique qualities. Even when it's fully loaded, you can still release the hitch. This is great when you’re moving DOWN a rope, such as a rappel backup. (You can use this for ascending as well, but you lose a few inches of slack every time you weight the hitch, and it’s harder to slide up the rope due to the increased friction from the extra wraps.)
Check this link to see an “animated knot” sequence of how to tie it.
So, how can I use the VT prusik?
The VT hitch can be used as a rappel backup attached ABOVE your rappel device. Normally you would not do this, but because you can release the VT hitch under tension, it works fine.
In the unlikely event you might ever need to “rappel” a rope that’s under tension, a VT hitch lets you do this, because it's releasable even when loaded.
You can use it to more easily pass a knot, again, because you can slide the prusik even when it's holding your full body weight. (Side note: you should pretty much never have to pass a knot if you set up your rigging correctly.)
You can use it as a third hand / French prusik / autoblock backup beneath your rappel device anytime you’re doing a lower or rappel (similar to a Sterling Hollow Block). The VT prusik lets you more easily fine tune the amount of friction than a loop style autoblock. Note, it’s best to do this with a rappel extension.
You can use it as a quick draw, either halved or at full extension.
You can use it as a personal lanyard; clip one end to a locking carabiner or quick link on your harness and the other end to a locking carabiner.
In a hauling system, like for 3:1 “Z drag”, you can use it as a progress capture device on a non-prusik minding pulley. Because of it’s width, the VT prusik is less likely to get sucked into the pulley like a standard prusik loop. See image below.
Sweet! Where do I get one?
As with most aspects of rope work, it's a better show than to tell. Watch this YouTube video below made by Rich Carlson, the inventor, for a complete review of his clever tool.