Update: 7-JUL-2010 7:30PM
First, I changed the cordage and turns and it works and worked well. In fact it works so well that now I am very uneasy about presenting an experimental system that I have little experience with and no real testing. For all I/we know it could suddenly fail with no warning for no apparent reason.

The orginal videos are back up and a new and improved setup added (see new thread for details on the improved setup):

http://www.youtube.com/watch?v=l-LllBrbIeM

http://www.youtube.com/watch?v=MFIxuM4H83k

Since I cannot 'unpost' what has already been read and/or said:
If you choose to experiment with this, be aware that it is an untested system, we have no real experience with it, for all I/we know, it could suddenly and catastrophically fail. Be extremely careful. Always use safety knots AND a full backup system in case of an unexpected failure.

I do NOT know know and have no way to determine how safe or reliabile this system is. Only testing and time can determine that.

Based on the glazing on nylon hitch material I saw tonight, it is possibe to melt a nylon or polyester rope, the hitch cord, or both. You must assume the hitch could suddenly release and drop you without warning. This is a completely untested, experimental method.

I went straight to my practice tree and tried this method; it worked pretty good for me five times -- once each at 3 feet and 10 feet and three times at about 15 feet or so. I also tried it with a couple of different Blake's configurations but Ron's suggestion seemed to be the easiest. Nothing was perfect, but I felt like I'd always be able to come down.

I also tried tying a standard B53 with a splittail on on a 13mm safety blue rope. I'd done this about 10 years ago and couldn't make it work, but I decided to try it again. Today I also used several different thicknesses of splittails to see if anythnig would work.

The results were mixed -- the best fit for an SRT ascent using just one Blake's hitch turned out to be a 13mm splittail, which worked two out of three times at 15 feet when using a B42 instead of a B53. The third time it jammed up and I had to use two hands to break the knot and get it to come down; after about two feet it began to work properly.

The one observation I could make was that smaller the diameter of the splittail, the harder it was to pull down.

All of my testing, though, was done only on New England Safety Blue (the first rope I grabbed when I headed toward the back door) so it's very likely that different kinds and diameters of ropes will act differently.

Interesting stuff, Ron. I've never thought of running tandem friction hitches as a solution to the problems associated with going up and down on a single hitch on a single line. Have you tried using a slack tender under the hitches while climbing?

My video with the soft uni on PI is up now too:

http://www.youtube.com/watch?v=l-LllBrbIeM


It's definitely a work in progress. I'm pretty sure optimal combinations of materials and sizes will improve performance.


A helical may be the answer Bill, it'd be worth a try. I used 10mm Beeline on both Velocity and PMI 10mm EzBend on SRT and it climbs like crazy - releases cleanly, advances effortlessly, and grabs fast. You might try the helical with the 13mm splittail, it just might be what you're looking for. And, you can experiment with the turns. I've seen them with as many as 9 turns. The 'tightness' of the helical matters too. Not real finicky, but sometimes can make a difference.

Absolutely no doubt about that!

]

I didn't try that, but I think that would work well. When advancing though, the footloop ascender (below the friction hitches) are applying a load to the cliimbing rope so you couldn't use the slack tender - I've I'm understanding you.

I'm guessing Dietley means a hitch tender/advancer not a "pure" slack tender but I could be wrong. Idea being it would be nice to rig a HUT to automatically advance the hitches for ascent.

Note: I think the terminology confusion arises because a slack tending pulley is used to redirect the tail to advance the hitch as well as take out slack when the climber's feet are on the tree, typically for an adjustable lanyard but also in a main climbing system. For SRT "slack tending" doesn't make much sense except if you're climbing on the tree and using the SRT system as a "belay".
-moss

Ahhhh, of course, I just didn't read it carefully enough.

I hadn't actually thought about a HUT, but that would work well. I was referring to a pulley or something similar, secured under the hitch(es) so it doesn't have to be advanced by hand. Any kind of device that is located under a friction hitch for the purpose of advancing the hitch, whether automatically or when the tail of the rope is pulled, is a slack tender to me!

I'm still trying to figure out what a "pure" slack tender is........

Ya me too. I was trying to differentiate between a hitch advancer (HUT) and a slack tender. Taking out slack may not always advance the hitch, ie: simply putting a pulley below a hitch isn't going to always provide hitch advancement, it does allow you to easily take out slack after you advance the hitch. In DRT if you put a pulley below the hitch and attach the pulley to the up rope with a prusik then you have a slack tender and a hitch advancer.
-moss

Ron, remembering your excellent work in this area, I recently watched a video that might interest you. It's part of a video series introducing some new products. But, it shows SRT ascent/descent using hitches as the friction elements. Also part of the system is a revolver and hitch climber. However the two hitches controlling the ascent/descent might be of particular interest to your work ... especially, what could be termed, a "soft" RADS system.

Make sure to watch the following portions:
Descending (7:10-7:15), using hitches to descend SRT.

Ascending (7:16-7:30), essentially using a 'RADS' type technique with hitches ... add a foot loop it would be a RADS ... sorta. Actually, it's better 'cause you don't have to remove anything to transition to a descent ... it's not even necessary to disconnect the tail of the rope from the pulley, which I find particularly interesting. It seems to go up and down without any configuration changes ... worth trying IMO.

Just thought you'd be interested ...

Regards, Jack

Ron and Jack thanks for the ideas posted here. I've been trying to make the jump to climbing the whole tree SRT and these are some great ideas. I recently made my own rope wrench which works well but I would prefer to do it with just hitches.
Cool thread
Ben

Hi everyone.

After the inspiration from Ron and his double hitch SRT system, I thought I would give it a try and attempt to incorporate a pulley/slack tender. Unless it is not obvious from the poor photos, I'm testing a distel above and a michoacan below with the hitchclimber below that.

It seems to work ok on a few little tests on a short SRT lanyard (backed up on my main climbing system). I think I am going to try a knut hitch on top next with the michoacan beneath and see if it is any better. Having the distel is a bit too much friction I think.

Another really useful feature is that I can throw my lanyard over my should and clip into the middle hole of the hitch climber. Nice versatile HUT to use moss's term.

Anyway.. What are your opinions on any safety issue/ problems with this system? I am going to splice up another Armor pruss friction cord to replace the beeline up top to slim the system down a bit at the carabiner.. Any other ideas?

If you can use an HMS style or pear shaped carabiner you'll have a little more room for all the eyes. Trying to figure out how this is different than using a one long hitch cord with many coils/wraps. Interested in hearing how it works on a climb.
-AJ

moss,
Two are really different than one long. I found most of the friction is applied by the upper coils. Hence, adding more coils doesn't really provide much more friction.

I also found that with a single hitch, be it long or short, when full weight is applied on SRT, again the top coils bear most of the weight and dig firmly into the rope.

As I though about how well friction hitches work on DDRT, I came to the conclusion that it's because the friction hitch has only half the load. Really less than half since some friction is provided at the TIP. So I figured the only way to have half the friction on SRT is to have two hitches configured to equally share the load.

So, for anyone 'experimenting' here are a couple of pointers.

1- You cannot use independent hitches. I.e. just tying two separate hitches and terminating them on a biner won't work well - they don't load share and inevitably the one with the most load will lock up.

2- If the strands from the top hitch contact the coils of the lower hitch, it tightens up the lower hitch upper coils and it starts to bind and then locks up.

3- The self-equalizing, equal load sharing configuration is important in the rappel mode. The top hitch has to be able to push the bottom hitch down without locking it up. The only top hitch I experimented with that accomplished that was the Schwabisch.

4- I slightly melted some low temp cordage and then went to high temp cordage. I noticed some 'melt' on my Velocity rope, but I can't confirm that the tandem hitches did that. But you need to be aware that is a possibility.

I dont really know the in and outs of it at the moment, but thanks for the tips. With certain combinations of hitches I managed to get them to share the load fairly well, but with some other cons such as poor advancing due to too much friction.

I think it is going to be a long experiment. Looks promising so far. Will have a go with a long hitch cord too moss.

With your joined balancing hitches do you tie them first and them make the loop endless with the double fishermans knots Ron?

I was thinking of splitting the bight from each leg of the balancing loop part either side of a hitch climber so I can still use the lanyard to make a 'chest ascender'

Thanks for the feedback.