"No-twist Munter" for Hanging Rap on Double 5.5mm Spyderline
and 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'. 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!
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'. 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 burnt 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.
