no-twist spyder

"No-twist Munter" and Supermunter for Hanging Rap on Double 5.5mm Spyderline
and "no-twist" on Double 3.2mm Amsteel (Dyneema)

This idea comes from Alpine Savy, and is really a supermunter with the brake strands not run through the biner; but the amount of friction is somewhat adjustable (by hand position) and less, compared to a supermunter.
This is a continuation of my tests of hanging raps on thin cords.

This is the setup for the "no-twist" Munter hitch:

A supermunter would differ only in having the brake strands clipped through the biner, and exiting the biner on the top of the spine.

5.5 mm Spyderline

Here are the forces seen by a linescale 3 hanging below the ceiling anchor, for a short hanging rap of less than 10' with "no-twist Munter." I "jump" a few times at the end of the rap, to induce dynamic forces, as in my other tests. (I weigh less than 145 lbs in my harness.)

The Spyderline has a PET sheath on a Dyneema core, and has a reported tensile strength of 3000 lbs per strand. Claimed diameter is 4.8 to 4.9mm, but my measurements suggest ~5.5mm when the rope is unweighted.

This is a video of the test:

The second jump hurt!

OK, how does that compare with a Spyderline rap on a regular supermunter? Definitely faster, with less extreme excurions, especially after one starts moving. For the supermunter, I had to keep yanking the brake hand up to allow enough slack for me to keep moving, for the first 10 seconds.

3.2 mm Amsteel Blue (Hollow-core 12 strand Dyneema)

Here are the forces seen by a linescale 3 hanging below the ceiling anchor, for a short hanging rap of less than 10' again with "no-twist" variant on two strands. I "jump" a few times at the end of the rap, to induce dynamic forces, as in my other tests. (I weigh less than 145 lbs in my harness.) I'm skeptical about recommending this hitch for thin Amsteel; it is easier to have the cord slip too much on a really tough excursion, like my third jump -- I did control it, but the thin cord abraded my fingers as it slipped. This Amsteel has a reported ATS of 2500 lbs per strand, and has no sheath.

This is a video of the test::

On the last jump, the cord slid enough to "burn" my fingers by abrasion.

So how does the no-twist variant compare with the supermunter on Amsteel? It's slightly faster on the hanging rap, which might be important as one is creeping to the start over mildly-sloped rocks.