More friction on SRT

[Tom Dunlap]

Yesterday I got an idea for a way to add a bit more friction under my climbing hitch on SRT. It's raining today so I won't be able to take it for a test drive.

I've been using a 4 over 1 distel and Knut. They both work very well. On descent either of them gets a bit jerky. Also, any SRT setup will generate a lot of friction.

I took one of the small aluminum rings from the bridge of my climbing saddle. A bite of rope goes through the ring and then the bite is clipped into my biner. The ring acts like a slack tender under the hitch on ascent. I should be able to pull down on the tail of my climbing line and get the ring to suck into the top of the biner to add friction. This will act like a Stitcht plate or any of the tubular rap devices like the ATC or tuber.

This week I'll be climbing and I'll get some pictures.

I hope to have this version tweaked a bit for my SRT talk at Expo.

 

[Mark Chisholm]

Tom,
That sounds promising. Good luck and get some pics. /forum/images/graemlins/grin.gif

 

[TheTreeSpyder]

i've tried morphing hitch and metal for SRT friction hitch solution, never could get the right combination to that puzzle.

It always seemed that if the metal was in place for sticht plate type friction on descent; then you have to push up against it on ascent. Tried moving it some between the 2 positions to affect desired results; mebbe ya got different angle; after all this has been kinda your baby!

In general; i fell back to previous theory, that DdRT slip and grip was because the load could switch to the static line, to afford slip on descent was tghe secret of DdRT,and the single line of SRT didn't give this option.

Good L.U.C.K.,
(Labor Under Controlled Knowledge)
-KC

 

[Kevin]

My feeling is that the more friction there is on the line the better the hitch will work as in using a false crotch.
With SRT there isn't any friction in the line so the hitch will slip easier.
Just a guess on my part.

 

[Treespotter]

Friction on the line?

What friction. The only friction there is, is from the friction hitch right?

Using drt means only half of the pull on the hitch at double the speed (hitch/rope speed).
I've never used the srt system, but what Tom spelled out (beiing able to do the rescue without getting into the tree) made a good point to me. I'd only would probably constantly be thinking "is someone fiddling with my rope right now".

If you still want to use drt than there is the option of using a pulley on a long line to the grownd to use as a tie in point.

 

[Kevin]

The friction from the rope running through the friction saver rings is what I was referring too.

 

[TheTreeSpyder]

Any friction saved by 'friction saver'; must be maid up at hitch; the toatal friction force, must equal support needed. So, SRT will have lots of hitch friction, DdRT with pulley TIP will have half at hitch, etc.

The bend of line running over the 2 1/2" rings totals a 1" curve, lowering on a 1/2" line thru a 1" curve is improper/over leveraging. i think that the friction saver is legit, because the weight doesn't slide, loaded thru the rings fully like lowering thru a pulley. But, rather DdRT thru the rings, employs the principal of the load jumping across air to the other leg of support, i think. So, is accepted as more proper for the 1" arc; which would be more proper in general terms for a termination, and not a pulley lowering strategy.

 

[Kevin]

I don't trust the friction on a 4/1 Distel on srt like I do on a doubled rope through a friction saver.
Add a little extra weight like a saw and it changes a controlled descent to a free fall using srt.

 

[chris_girard]

Kevin, I was thinking about using the 4/1 Distel on SRT but what hitch would you use if you think there is too much slippage?

 

[RemovalWizzard]

I don't quite understand how the small ring and biner will tend slack during the ascent..... But i have used the same system in place of a Figure 8...... works great, but you better have your gloves(the smaller the ring the better the friction).

on another note i have started using a small prusik(french) on a single line..... attached to the prusik i have a micro pulley and my DdRT climbing line through the micro pulley.... i use the prusik to ascend and to lock my DdRT in place, back it up with a biner and a clove hitch.... gives me chill bumps just thinking about it.

 

[Kevin]

Chris;
I'm not in a position to answer that question because I haven't experimented much with anything other than the Distel.
If in doubt I would opt for the 4/2 or back it up with an 8 away from the hitch on srt.
I had experienced a failure with the 4/1 where I dressed and set the hitch prior to dropping out of the tree.
The hitch held fine but when I touched the top of it I went into a free fall.
Lucky I was up high enough in the tree, I grabbed the top and bottom of the rope thinking I could slow down enough to get the hitch to catch but it didn't work.
I reached the point where I had to let go of the rope because my hands were burning.
I waited for the abrupt stop at the ground but the hitch kicked in on it's own about ten feet off the ground and stopped my descent.
I happened to have ice in my cooler and went directly to it and grabbed a couple of ice cubes.
That saved my hands from blistering and I suffered no ill effects.
By grabbing the rope from the below the hitch I may have made matters worse by not allowing the rope to bunch up under the hitch.
If it happened again I would try and concentrate on gripping the hitch and forcing it up.
Lately I've been using the 8 secured off my side D when using srt.

 

[Jim]

Tom,

just wondering if you were able to test out your idea. It looks interesting.

Jim

 

[Stumper]

Kevin, SRT is a whole different ball game-the big problem is getting hitches to release. You need a hitch that will catch every time without fail but will still release smoothly ( when released intentionally) under load. Part A is easy to find. Part B is an ongoing search.

 

[sizzler]

Tom, is this sorta what it would look like? Thats a ring from REI rated at 50kn and a steel biner. i tried it out rappelling off the balcony in front of my apartment first with this and then with a figure eight to compare. Here's how it went (for lack of better name call it R&B or ring and biner)

Ddrt with R&B: too much friction, was not able to descend at all. /forum/images/graemlins/shakinghead.gif

Ddrt with figure 8: ah... just right. Good control./forum/images/graemlins/eyeye.gif

SRT with R&B: A good amount of friction, allowed good control of the speed and start/stop motions./forum/images/graemlins/spinrhead.gif

SRT with figure 8: too loose, like unsafe diarrhea/forum/images/graemlins/vollkommenauf.gif

Another plus of the R&B was that it kept the rope perfectly straight and in line and both hands can use the setup, unlike the figure 8 which twists the rope sideways and has to be unclipped turned to change hands./forum/images/graemlins/rock.gif

 

[pantheraba]

Good test and write-up, Sizzle. I like the "no twist" of the rope...also weighs a lot less than an 8.

 

[Norm_Hall]

Sizzler, did you use that set up with a friction hitch on the SRT line?

 

[sizzler]

thanks Panthro

Norm, i knew someone would ask, no i didnt, but i was only a few feet off the ground. i wanted to feel just the devices. if anyone is planning to get mad at me for not using a hitch, save it. i would never decend a tree without a backup and i am perfectly aware of the risks of falling a few feet so dont lecture me.

 

[tod_k]

That may be a good way to back up a hitch while working a spar srt.

 

[Jim]

Sizzler,

Where did you attach the 'biner to your saddle? To use it either hand, I would think it would have to be attached somewhere towards the center.

I wonder if that would allow for a better SRT descent with a hitch. It seems like it would offload some of tbe friction from the hitch itself.

I wonder if this method would tend to knarl the line over time, as the figure 8 does.

Jim

 

[sizzler]

it was attached to the D right in the middle of my harness. heres a fuzzy picture, but you can see just the tip of the D. knarling the rope is a realistic concern. i noticed that my rope looked a little bent from all the bending.