Ryan called me up asking if I had any VT Prusiks to do some testing with. I said, "yep, what size?" He responded, "there are different sizes?" I laughed and said, "yes, 7 and 8mm." He said, "bring em both!" And then said, "would you be interested in doing a video about VT's?" So here we are...
I was introduced to the VT in a canyoning course I did with Rich Carlson and since then have seen the VT showing up in multiple rope disciplines. Arborists have been using it for a while and the SAR community is using it more and more. By weight, I think it is the single most useful piece of kit you could have on your harness. With a VT and the knowledge of a few knots, you can be a very capable rope technician.
We pulled the 8mm and 7mm Bluewater VT Prusiks on 10mm, 8mm, and 6mm diameter semi-static nylon ropes. As a bonus, we pulled it on a Dyneema-sheathed rope that had very interesting results. I was particularly interested in how much force could be on the VT and still be able to release it. This is useful to know when using the VT in load-releasing situations. Secondly, I really wanted to know the limitations of the VT performance on different ropes.
I demonstrate a use for it in canyoning and Cory Grossman showed us a few tricks that arborists do with it.
Here is advice from Shane Wallace, a guide and instructor in the Southwest
Tying the VT is where I see issues that lead
to the VT not performing as expected. Tying it isn't complicated but requires attention to the process. The first part is wrapping the VT 3 times around the host rope. There is chatter about people using 2 wraps or 4 wraps but I always use 3. I have experimented with 2 or 4 wraps but that was when I was having issues in the beginning. Once I developed a specific process to tie it, I've always used 3 wraps and it works perfectly. That doesn't mean that 3 wraps is your number but I teach it with 3 wraps, watch it used with 3 wraps, personally use it with 3 wraps and when it is tied correctly, there has not been an issue. I recommend 3 is where you start. If the host rope is hanging vertically in front of me, I place the VT on the side opposite from me and wrap it. The wraps are snug but not tightly pulled. After 3 wraps the tails are also on the side opposite of me with one extending to each side of the rope. I let the tails hang down and parallel to the host rope, checking that they are the same length. This is one check I consider to be critical. If the tails are the same length when positioned in the direction they are to be loaded, in this case vertically, they will not be the same length when pulled perpendicular to the host rope. I see people checking the lengths perpendicular to the host rope. This leads to one strand being longer than the other when the braiding process begins. There are no tests that I know of but it is my belief that when one strand is longer than the other before braiding, it leads to unbalanced loading where the VT becomes too tight and binds up or never grabs.
Once the tails are the same length the braids begin. But do you braid with the left strand or the right strand? It depends! As I wrote before, after wrapping the VT you will have a tail extending to each side of the rope and one of those tails will be higher on the rope than the other. Either the left or right tail is higher and this is determined by the process and direction you wrap the VT on the rope. The side that is on top is the side you start your braids with. As the braids commence, the braid will alternate from the side closest to you to the side away then back to the side closest to you until you run out of material. If the right side is the high side, after wrapping and matching the lengths of the tails, you will start the first braid with the right side. Cross the right side down and to the left and then cross the left side tail over the cross made by the right tail. Then hold the tails out perpendicular to the rope, one tail in each hand. I call this one braid. After each braid you will start the next with the right hand because the right strand was on top in the beginning. Make the next braid by crossing the right tail behind the rope and crossing the left tail over it, then hold tails out again completing another braid. Continue until you run out of material. Keep the braids stacked next to each other to maximize the number of braids.
There is a simple check I use to inspect a Valdotain Tresse. I find the strand that is highest after the wraps and follow it down. The highest strand should cross over and touch the rope on the front side and cross over the other tail of the VT on the back. The same pattern occurs when looking at each braid. The result is a confirmation that each tail takes its turn contacting the rope. If one tail simply wraps around the rope and the other tail never contacts the rope, there is an issue that results in uneven loading of the VT. It is my belief that uneven loading such as this leads to a VT hitch that locks up or never grabs.
So what size should you use? That depends of course. Hopefully after reading this you will be able to make the correct decision for YOUR needs as a recreational canyoneer or guide. What works for one person may not work for another. Anyone that specifically or absolutely recommends one size over the other is likely based on their experience and possibly their inability to use it correctly. But if they say something like, "The VT binds if you use the 7mm so only use the 8mm" then they are blaming the VT for their possible inability to use it, teach it or tie it correctly. The properties of the core allow for the 8mm to be used on various diameters of rope including an 8mm. Although I find that using an 8mm VT on an 8mm rope requires diligence and precision when tying it to achieve the desired function. Typically what I see when the 8mm VT is used on an 8mm rope is that the VT slips because the initial wraps need to be more snug. I believe as rope diameters became smaller and smaller there became a need for the 7mm VT. I personally prefer the 7mm VT instead of the 8mm. When the 7mm VT came out I instantly liked it better than the 8mm and I think that is because I mostly use 8mm ropes. I carry one 7mm VT on my harness and an extra in my pack. If you use 9 or 9.5mm ropes then the 8mm VT may be your choice but I know I can use a 7mm VT without fail on any diameter 8mm to 9.5. Just as there are different rappelling devices there are different sizes of VTs. My suggestion is 7mm for recreational canyoneers for multiple reasons but you should decide for yourself.
Tips for using the Valdotain Tresse.
Make sure the wraps are snug.
After wrapping, make sure the tails of the VT are the same length when positioned parallel to the host rope.
Make sure the braids allow for alternating contact of the tails of the VT with the host rope.
When using the VT as an autoblock above the device, DO NOT allow the VT to become partially engaged and used as part of your friction system. Pull the VT down close to your rappelling device and hold it there. Allowing it to partially engage while rappelling may lead to some tightening of the VT potentially causing it to lock up. Knowing how to self-rescue is a valuable skill if this occurs.
Lastly, when using it as an autoblock, don't grab it with your entire hand and release it with your thumb and finger. The thought is that if someone panics, they will continue to grab the autoblock with their hand and it will never grab. I have coined the term "smoking the VT. When using the VT as an autoblock, hold it in its released position using the first and middle finger with the host rope between those two fingers. The thought is if someone panics and squeezes, the rope will burn the inside of the two fingers and they will let go. Not very scientific I know but maybe others have a technique they use? I'm open to suggestions.
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Thanks for reading!!
Behind the Scenes
Ryan tried rappelling with a VT (on the auto belay of course) and found it is not that easy to get right the first time. Practice really does make better. 😂
After Posting Thoughts
We did do all these same test with the VT tied in the Distal Hitch and Schwabisch Hitch. Hopefully these videos will be released here...
Comment from Rich Carlson -
Here is a link to his VT video on Canyons & Crags - VT Prusik - versatile tool for ropework