I've been using a Yale XTC rope for two years without any problems, but recently my 4/2 Blake's hitch started slipping. I started using a 5/3 version instead, and thought I'd solved the problem, but today it started slipping too! What's up with that!?

I know the knots were tied right, I double and triple checked them (although I am still uncertain as to how tight one needs to keep a Blake's hitch). The rope certainly doesn't look worn, and it isn't glazed or anything. It doesn't seem to be terribly dirty, but there was a lot of dusty crud settling over me and the gear (this time, but not when the original 4/2 started slipping). Also, it seems to happen mainly on descent, not ascent or dangling.

What factors can cause this slippage, and what measures can be taken against them? Should I try washing the rope? Do something different with the knot? Help! Climbing is already thrilling enough; I definitely don't need the extra rush of adrenaline that this causes!

Brad

Hello, Brad--

I don't have an answer for you, but I do have some questions/thoughts:

1--Could moisture/humidity have anything to do with it? Has that been different?

2--How much did it slip? I assume that you grabbed the rope to stop the descent--did that take much work on your part?

3--Is it that the knot would hold you in place until you "pushed" on the top of it (to begin your descent), and then it didn't catch and hold once you took your hand off the knot?

4--How much do you and your gear weigh? And that prompts the thought, are you carrying more weight aloft now?

If #3 is true, then the answer from the engineering and physics worlds is that the dynamic coefficient of friction of the knot is too low to hold you, whereas the static coefficient of friction is high enough to hold you. What that refers to is that the frictional force may be enough to hold you *until* it begins slipping, but once the slipping has begun, it ain't gonna stop. I'm sure you've experienced that when pushing a heavy _object_ across a floor: you have to push with a certain amount of force to get it started moving, but once it is moving, you don't have to push as hard to *keep* it moving; and once it has stopped, you have to push harder again to get it going.

Of what value is that to you in your situation? Probably none, but you did get a free physics lesson. The next time it slips, instead of screaming and grabbing for the rope, you can calmly say, "Dear me--the dynamic coefficient of my Blake's hitch is too low."

Seriously, the knot does need more friction. Why now and not before? Beats me.

You commented that you were uncertain as to how tight it should be; I snug mine down pretty tightly--no slack.

I'm looking forward to hear what some who have experience with XTC, and others with a ton more experience than I have, might have to say.

Good luck!

Jim

The only time I've had a Blake's hitch slip with XTC was when the rope was brand new. My "fix" was to tighten the hitch, producing more bend of the rope through the middle of the hitch, and thus increasing the friction/holding ability of the hitch.

Testing your hitch by going up and down once or twice just off the ground, before ascending, may help catch descent problems before they become major risks. And some kind of "stopper" knot, tied below you but sufficiently off the ground, could be the difference between you sliding all the way to the ground or coming to a hard stop still on the rope if your hitch ever does allow an uncontrolled descent.

Thanks, guys.
In answer to your suggestions:
-- the mosture/humidity wasn't extremely different that day; somewhat warmer and drier than usual.
-- once the slip started, it seemed like it simply didn't want to lock up at all. There was enough friction that it took only a little work with one hand to control, and even stop, the descent. I could come to a complete stop, and as soon as I relaxed my grip, it would slip again. I was a little too nervous to try letting it go and see what happened!
-- yes, the knot held until I pushed it down for my final descent, and then wouldn't hold again. I should point out that I wasn't on the same knot for the whole climb; I was working with both ends of my rope, and had advanced my rope four or five times, re-tying the Blake's each time. On the last knot, I checked and re-checked visually, then hung on it and bounced my weight a bit, before untying my other anchor and unclipping my Monkeytail. At that point it gripped just fine! Jim, in terms of your explanation, I guess the initial static coefficient of friction was sufficient, but the subsequent moments of static coefficient of friction weren't?
-- I weigh about 190 lbs., and was carrying maybe 15 lbs. of gear and water. This would be about normal for most of my climbs. Is 200 -- 210 lbs. too heavy for a 4/2 or 5/3 Blake's hitch?
-- yeah, I keep my knots pretty snug, too. Enough that I sometimes wonder if I'm subjecting my rope to more wear than is neccessary!
-- Bradley, your suggestions are good. Tying knots below your hitch as you climb is a good safety measure and I make my kids do it all the time. Maybe I should start practicing what I preach! As for testing, I've always limited it to testing the static position, both initially and after one or two pulls. I think I will definitely get into the habit of doing a trial descent, as well.
Thanks again for the help!
Brad

I've had a similar thing happen on XTC. It hasn't happened to me on 7/16" ropes like Sportline or Fly. Maybe the thicker rope isn't turning quite tightly enough around the down rope?
Anway, what I usually do before I descend is to grab the tail end of the rope (the last few inches of rope that come out of the Blake's hitch) and pull straight up. That compresses the Blake's hitch a little more and increases friction.
Patrick

Brad,

I have a 3yr old XTC, and I've just started noticing this problem. I have discovered though, that it seems to happen more after significant climbing in a tree with smooth bark. I have ben climbing a pair of willow oaks on a reguar basis, and I tend to see a little slipping while in those trees. In a white oak or a yellow poplar I've yet to have the problem. Interesting thing is that I've always just let it go, after a few inches the knot seems to remember it's job and cinches down.

As far as the blake's configuration, I always use 4-2 with my XTC. 5-3 locks solid on that rope. On my sportline either works fine, but I'm so used to the 4-2 that I don't like to use the larger knot. Interestingly, my kids have difficulty advancing the hitch on the XTC, because it grabs so well, there is a paradox for ya!

Climb Safe! See ya between the trees!
Icabod