SRT Secret Weapon Question

[scrat]

Ok I have a simple question-
when working double rope off SRT it is generally shown with a prussik and pulley tied to the SRT (access line) with a stopper knot below it (butterfly knot) then your duoble rope is run off the pulley. Is there a specific reason the double rope set up is not just run on a pulley secured to the butterfly knot and thus eliminating the prussik? is this a safety issue or work convenience?

any and all input is appreciated
Scrat

 

[highclimber30]

I would think, that since the prusik is most likely girth hitched around the carabiner that holds the pulley which contains your DdRT system, that the carabiner is less likely to become side-loaded. If you could tie a butterfly tight enough around the carabiner that contains the system, or find another knot that would cinch down on the crbnr then you would be fine to do what you are talking about. I just don't think you will really be saving yourself any time. I'm sure there are probably other reasons that I am unaware of and I may be totally off base. Hopefully, some one else will chime in.

 

[MtnArb]

You can anchor directly into a marlin spike,if it is tied correctly, and it will cinch down on the carabiner.

 

[Waldo]

i just don't like to untie any midline knot after it has been loaded like that, prusik is way easier to untie.

 

[Waldo]

also, if you are working the tree from the bottom up you can just go back to your prusik and resume ascending

 

[treebing]

The secret weapon is a specific configuration, of course you can tie into the alpine butterfly, but then it would not be a secret weapon. Any old prussic is not a secret weapon. Use a ring to ring and there you have it.

 

[GibsonTreeCare]

If you rig your DRT system into the SW and use it to replace your tether; you can stop anywhere along the route, set your SW and work, then you can either ascend higher or start going down.
Once down, pull the DRT rope out of the SW, and lower the SW on the SRT line under control back to you.

A midline knot as Waldo says is too hard to untie after weighting,plus you can't have your DRT rigged in there and continue an ascent

 

[GregManning]

Depending on your ascent system setup (e.g. pantin & croll) you could attach your secret weapon with a prussic to the SRT line above the mechanicals.
Then attach your DRT climbing line to your harness before ascending.
(The DRT system becomes your “backup” for the SRT mechanicals; and you’re ready to go !)

Thanks Norm !

 

[allmark]

Yesterday I installed a srt set up. As the rope(being pulled by throwline)came over the anchor a few feet I stopped and installed a butterfly knot with my pulley and drt set up. Pulled it to the top and anchored my srt. I ascended with a mitchel srt set up replacing the lower ascender with a foot ascender. Ascended. disconnected the srt and left it on the line. I then proceded to work down wit the drt.

It worked great.I see no issues getting the butterfly knot untied with a climbers weight even if it was shock loaded. I used a smaall loop in the knot and cant see how the biner would be side loaded or rotated if staying below the tip.