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Valdotain Tresse: VT vs. XT

Discussion in 'Tech Tips and Gear' started by Sonny Lawrence, Jan 29, 2018.

  1. Sonny Lawrence

    Sonny Lawrence

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    Many of you may have used hitch cords with two sewn eyes. Some in the USA are made of a technora external sheath on polyester or nylon core. Two names are Tech VT by Atwood Gear or VT Prusik by Bluewater Ropes. They are used to tie a Valdotain Tresse hitch made popular in France and now used by arborists in the USA. There are many other varied uses for this device in caving, canyoning, rock climbing and technical rescue. There are a few ways to tie it as a releasable under load hitch. In this video () are two ways that are very similar. Both are releasable under load. Trying to release a Valdotain can be challenging. It can release either too fast or not at all.


    Paul Stovall and I did some backyard testing. We used both prusiks from Bluewater and Atwood. We tied them on 11 mm nylon caving rope, Sterling CIV canyon rope and Imlay 9 mm polyester canyon rope. We tried various configurations such as four vs. three wraps, the VT or XT method, then a few or many crosses. Paul weighs about 200 pounds. He subjectively rated the XT vs. VT as to how easy it was to control the release. Enough iterations were run to clearly point toward the XT method as best.


    However which method is best is ultimately dependent on personal preference and many factors with the rope and/or cord; dry or wet, clean or dirty, old or new, the material made of, etc. It would be informative for others to do their own backyard testing and chime in on this discussion.
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  2. Mike

    Mike epic blarneys

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    I found the VT to be a great tool for knot passing and weighted double strand pick-offs. I had trouble with the Bluewater version being too short for me to get enough wraps and hold well on a single strand 8mm rope (I think they made it longer since?). There may have been ways to make it work that I did not figure out. I ended up using a custom one that was a fair amount longer and I could get it dialed in perfectly.
  3. Sonny Lawrence

    Sonny Lawrence

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    This is good feedback for Bootboy and sizing for his product.
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  4. Bootboy

    Bootboy Atwood Gear

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    The 8mm is made in 3 standard lengths. 28", 30", 32".
    The 6.8mm comes in 2 lengths. 24" and 27"

    Custom lengths in both diameters are easily done upon request.
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  5. Bootboy

    Bootboy Atwood Gear

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    The 6.8mm works much better on skinny ropes than the 8mm. Fewer wraps are required with the 6.8mm to get adequate grip/holding power, hence its shorter length.
  6. hank moon

    hank moon lovely ligatures

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    Sonny, do you have more details on the testing? Such as: diameter and length of VTs used on the various host ropes + comments on release control for each test? Is there a video of the testing?


    Have you tested the Tech VTs w/a 2-person load? Is the cord used for the Atwood VTs "mushy" like the VT Prusik, or more firm?
  7. Sonny Lawrence

    Sonny Lawrence

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    No video, sorry. The Tech VTs were specially made for us by Bootboy. They were slightly longer with a bigger sewn eye to accommodate two carabiners. This allows them to be used for a French pickoff technique. In the test mentioned above, we only had a one person load. Last year we put a two person load with good success. We like the Tech VT. I would not use the word "mushy" to describe either Bluewater or Atwood prusiks. They certainly change how they feel as they get dirty and worn. I like them both. It is a huge advantage to be able to special order a particular size.
  8. hank moon

    hank moon lovely ligatures

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    Thanks, Sonny. re: "mushy" - perhaps pix are better than words in this case. The VT Prusiks I have are very soft with a sheath that is looser than any other cord I have seen. Presumably this characteristic is meant to simulate the softness of homemade VTs, traditionally made from a length of dynamic rope with several core strands removed (note: these are for use only when the VT is soaking wet, on a wet host rope, b/c of melting risk due to nylon rope materials). See pic below for pinch comparison of 8mm Bluewater VT with 8mm Sterling Canyon Lux (the softest cord I own).

    p.s. I s'pose it's worth mentioning that some degree of "Mushiness" is a desirable feature in a VT Prusik !



    8mmVTP.


    8mmcanyonlux.
    Last edited: Jan 31, 2018
  9. John Diener

    John Diener

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    How well does the 32" 8mm Tech VT work on say, a bundle of three 8mm ropes?
    -john
  10. Ali Miller

    Ali Miller

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    How about on Tom's 8.3mm Canyon Fire? Does that count as 'skinny'?
  11. Bootboy

    Bootboy Atwood Gear

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    I consider “skinny ropes” anything in the neighborhood of 9mm and under.

    The rule of thumb with hitch cord is that you want a cord that is roughly 3/4 the diameter of your main line. So the 6.8 is better suited to the “skinny” ropes
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  12. ratagonia

    ratagonia

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    "Skinny ropes" will have different meanings to different folks, but...

    Most of the ropes we use canyoneering are considered skinny ropes to almost anyone who is not a canyoneer. but...

    For canyoneers, I divide ropes into three categories:

    Skinny: Things smaller and 'faster' than Canyon Fire: BW Canyon pro, Sterling Lux, Atwood Grand, Imlay Canyon 8.0 (which I still have but definitely don't push).

    Small: Canyon Fire 8.3, various similar ropes, Sterling CIV (which is 'fatter' but soft).

    Canyoneering-Fat: Canyonero 9.2, and other 9mm-ish ropes.

    As always, I will point out that "diameter" is not a technical statement and ropes with the purported same diameter can be very very different. gms/meter tell you more about the rope than the diameter number assigned by the marketing department.

    Tom
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  13. ratagonia

    ratagonia

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    I think not, because, while it is 8.3mm diameter, it is dense and burly. But, I suspect the smaller diameter VT will work well on it, and I do not really see a downside to using the smaller diameter.

    Tom
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  14. Sonny Lawrence

    Sonny Lawrence

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    Recently I was working with SAR students on vertical rope work. I borrowed one of their Bluewater 7 mm VT Prusiks to build a releasable system with their 11 mm nylon low stretch rope. I tied the usual Valdotain Tresse. They loaded this system with two people hanging free. I could not get the VT to release until it was unloaded. Is a 7 mm VT too skinny for 11 mm rope? Do I need to tie a 7 mm VT differently than an 8 mm VT on the 11 mm rope? That experience caused me to ask, which diameter of VT is best for canyoning. There might be a big difference between a 7 and 8 mm VT. If the 8 mm VT can be made to work on the skinniest of typically used canyon ropes, it will be the better choice. Something to test once I have a 7 mm VT.
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  15. ScottM

    ScottM Looking for a canyon, you got one?

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  16. hank moon

    hank moon lovely ligatures

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    @ScottM what method is that? I'm curious b/c some presenters* insist on a certain method (e.g. braiding always begins by passing top arm - coming from the top of the wraps - under the bottom arm, then alternating over/under) and others don't. The BT VTP instruction set is silent on this point. What do you think?

    *such as the one in the OP YouTube video
  17. ScottM

    ScottM Looking for a canyon, you got one?

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    I will typically capture the top arm with the last loop of the wrap (at the bottom) then start alternating with the braiding
  18. scottensign

    scottensign

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    I did my first Heaps Saturday and was the first one down on the final rappel. I put a bluewater 7 mm VT prusik as an autoblock above my rappel device on a 300 foot canyonlux 8 mm rope. Five wraps followed by three braids. Tested at the top and it held very tight. I tested it again a few times on the way down. By about 2/3 of the way down it would not hold at all- it would slow the rappel, but not engage for full stopping. Just an FYI for anyone planning to use these as an autoblock on a long rappel. I guess I could have tied off on my critter and added more wraps, but I wasn't that worried about having the autoblock by 2/3 down anyway as I was feeling pretty good and enjoying the amazing ride. Shows yet again that autoblocks are not fail proof and need to be used with caution.
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  19. ratagonia

    ratagonia

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    Autobloc above the device is unlikely to engage in the most likely long rappel failure, loss of control. Your autobloc "above", even when it "worked" was likely just "security theater", rather than an effective self-belay.

    For the autobloc (of various kinds) to work, you would need to let go. You are unlikely to do so. In a caving context, evidence suggests that the out of control rappeller only lets go of the autobloc when they hit a ledge and break their femur. (2 incidents reported)

    Some people are confused by anecdotes when such an event works. To be an effective technique, it needs to work most of the time, preferably ALL the time, rather than once in a while.

    Tom
    Last edited: Jun 3, 2018
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