Possible new knot!

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Possible new knot!

Postby WVCaver2011 » Feb 10, 2009 4:10 pm

Hey CaveChat,
I was rigging a figure eight a long time ago and had a pretty good knot Idea that was quick to tie and I thought it might work really well. I used it and it worked great and never slipped not even the slightest amount! I've carried heavy baggage and stuff in and out of the cave and have used it approximately 25 times since I made it. Each caving trip counts as one time! I thought I would share the knot with you guys to see what you thought about the knot and to see if you think it's okay to use! Here it is:


Image

Let me know what you think!
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Re: Possible new knot!

Postby Scott McCrea » Feb 10, 2009 4:14 pm

Allen, I edited your post to imbed the video.

I don't like your knot. Look up the tensionless hitch. It will serve you better.
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Re: Possible new knot!

Postby WVCaver2011 » Feb 10, 2009 4:29 pm

Scott McCrea wrote:Allen, I edited your post to imbed the video.

I don't like your knot. Look up the tensionless hitch. It will serve you better.


Ok, I will look up the tensionless hitch thanks!
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Re: Possible new knot!

Postby Carl Amundson » Feb 10, 2009 4:31 pm

Your knot looks like a granny knot with a half hitch at the end.
I agree with Scott that a tensionless hitch is the way to go.

All knot takes away from the strength of the rope.
Some more, some less.
A tensionless hitch does not decrease the strength of the rope at all.

The Tensionless Hitch
http://www.animatedknots.com/tensionless/index.php

But you don't need to put a biner at the end.
use a follow thru figure 8 instead.
Last edited by Carl Amundson on Feb 10, 2009 4:48 pm, edited 2 times in total.
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Re: Possible new knot!

Postby Ralph E. Powers » Feb 10, 2009 4:35 pm

I concur with the others... tensionless hitch or a tensionless wrap does very well and is easy to untie. How easy is your knot to untie after putting a load on it?
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Re: Possible new knot!

Postby Anonymous_Coward » Feb 10, 2009 4:46 pm

The main advantage of the tensionless hitch is that the full strength of the rope is retained. Any knot under load will decrease the usable strength. In the knot you posted, the load causes most of the force to concentrate where the first loop in the standing line squeezes the other end.

In the other thread you claimed that you could hang two trucks with this knot and that the rope would break before the knot would. Actually, your knot is precisely where the rope would break in that situation. The small diameter of the loop causes an extreme squeeze point. If the system was loaded to failure, the rope would likely be literally squeezed in half at that point. If I read your knot right, all hell would break loose after that.

Knots with larger diameter turns are stronger for this reason, that is why the figure 8 is so well-loved with its broad, sweeping turns.

The tensionless hitch takes the concept one step further and removes the knot completely from the load. We usually use the figure 8 on a bight in the tensionless hitch, (because it is our favorite) but the knot is really just there to make you feel better. The turns of rope around the anchor are what do the trick. The way junkman recommends will work but I like using a carbiner. Slap a carabiner in the system and you have easy, fast rig/de-rig capability. The 8 on a bight is faster/easier than the follow-through.

Your average 11mm rope in good condition on a good day will have a theoretical breaking strength of around 6000 lbs. The tensionless hitch will let you retain all of that. A good knot (like a figure 8) in a rope around a tree will knock you down to about 4000 lbs. I would hazard a guess that the knot in your picture would get you down into the <3000 lb. range.

Learn the classic caving knots. They have stood the test of time for a reason.
Last edited by Anonymous_Coward on Feb 10, 2009 5:13 pm, edited 1 time in total.
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Re: Possible new knot!

Postby WVCaver2011 » Feb 10, 2009 5:03 pm

Okay guys, thanks a lot. That seems easy enough to use and It doesn't require any loss of rope strength. I'll use it, thanks.
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Re: Possible new knot!

Postby WVCaver2011 » Feb 10, 2009 5:22 pm

jaa45993 wrote:The main advantage of the tensionless hitch is that the full strength of the rope is retained. Any knot under load will decrease the usable strength. In the knot you posted, the load causes most of the force to concentrate where the first loop in the standing line squeezes the other end.

In the other thread you claimed that you could hang two trucks with this knot and that the rope would break before the knot would. Actually, your knot is precisely where the rope would break in that situation. The small diameter of the loop causes an extreme squeeze point. If the system was loaded to failure, the rope would likely be literally squeezed in half at that point. If I read your knot right, all hell would break loose after that.

Knots with larger diameter turns are stronger for this reason, that is why the figure 8 is so well-loved with its broad, sweeping turns.

The tensionless hitch takes the concept one step further and removes the knot completely from the load. We usually use the figure 8 on a bight in the tensionless hitch, (because it is our favorite) but the knot is really just there to make you feel better. The turns of rope around the anchor are what do the trick. The way junkman recommends will work but I like using a carbiner. Slap a carabiner in the system and you have easy, fast rig/de-rig capability. The 8 on a bight is faster/easier than the follow-through.

Your average 11mm rope in good condition on a good day will have a theoretical breaking strength of around 6000 lbs. The tensionless hitch will let you retain all of that. A good knot (like a figure 8) in a rope around a tree will knock you down to about 4000 lbs. I would hazard a guess that the knot in your picture would get you down into the <2000 lb. range.

Learn the classic caving knots. They have stood the test of time for a reason.


Excellent, it's nice to hear from someone who shows they know what there talking about! I've learned the Figure 8, figure 8 on a bight, and the butterfly, Nothing else, but i figure that was good enough, However, I plan to get as many knots under my belt as I can because you never know when you might need another knot!
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Re: Possible new knot!

Postby Anonymous_Coward » Feb 10, 2009 5:45 pm

WVCaver2011 wrote:I've learned the Figure 8, figure 8 on a bight, and the butterfly, Nothing else, but i figure that was good enough, However, I plan to get as many knots under my belt as I can because you never know when you might need another knot!


Sounds like a good plan! Just remember that it is better to know a few knots REALLY well than it is to know 20 knots KINDA well. The ones you mentioned will do most of the things you need a knot to do in a cave. Get to know some that do other things like water knots, prusiks, barrel knots, and you'll be in good shape.

Just always keep learning. You'll find that most people you want to go caving with are the ones who are constantly learning more about it. It's the ones that know it all that you have to worry about.
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Re: Possible new knot!

Postby knudeNoggin » Feb 10, 2009 7:25 pm

WVCaver2011 wrote:
jaa45993 wrote:The main advantage of the tensionless hitch is that the full strength of the rope is retained.

Not that the full strength is needed. But the broad wraps will reduce
the effects of use on the rope (though accent them a bit on the tree
--load all on the one strand, and more stretch/movement to it).

The small diameter of the loop causes an extreme squeeze point.
If the system was loaded to failure, the rope would likely be literally squeezed
in half at that point. If I read your knot right, all hell would break loose after that.

Well, I think this goes too far. I doubt that the rope could cut through
the end; rather, IF that geometry held--and I doubt this --, the main
line would break there, and well above 2,000# (33%?!). But what will likely
occur is that the turn will capsize, putting the turn into the end and loading
the mainline's next turn, which might repeat the behavior: if all go, then
you'll have a more conventional and venerable 3 Half Hitches, and good
for maybe 70% in this set-up.

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Re: Possible new knot!

Postby WVCaver2011 » Feb 10, 2009 7:37 pm

knudeNoggin wrote:
WVCaver2011 wrote:
jaa45993 wrote:The main advantage of the tensionless hitch is that the full strength of the rope is retained.

Not that the full strength is needed. But the broad wraps will reduce
the effects of use on the rope (though accent them a bit on the tree
--load all on the one strand, and more stretch/movement to it).

The small diameter of the loop causes an extreme squeeze point.
If the system was loaded to failure, the rope would likely be literally squeezed
in half at that point. If I read your knot right, all hell would break loose after that.

Well, I think this goes too far. I doubt that the rope could cut through
the end; rather, IF that geometry held--and I doubt this --, the main
line would break there, and well above 2,000# (33%?!). But what will likely
occur is that the turn will capsize, putting the turn into the end and loading
the mainline's next turn, which might repeat the behavior: if all go, then
you'll have a more conventional and venerable 3 Half Hitches, and good
for maybe 70% in this set-up.

*knudeNoggin*


Really, wow, that basically puts it up there with the figure 8 in strength if I read this right you're saying that the knot will hold about 70% of the breaking tension of the rope. So, would you trust this knot for rigging drops? :waving:
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Re: Possible new knot!

Postby Anonymous_Coward » Feb 10, 2009 7:48 pm

knudeNoggin wrote:Well, I think this goes too far. I doubt that the rope could cut through
the end; rather, IF that geometry held--and I doubt this --, the main
line would break there, and well above 2,000# (33%?!).


I have no desire to continue this debate, as I am not an expert on knot physics, and had trouble interpreting the photo. (I could not access the youtube version) However, I would like to point out that I changed the 2000 to 3000 right after I wrote it, because that is what I meant to say originally. My point is that the rope would probably break there, as you noted.
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Re: Possible new knot!

Postby wyandottecaver » Feb 10, 2009 7:58 pm

LOL!

Allan, without presuming to speak for knudeknoggin, I *think* he is saying that your knot is unlikely to cut your rope in half as was suggested. Instead, it might fail at 33%. But more likely, your unconventional knot would *probably* collapse loop by loop into a more traditional 3 half hitches which might be good for 70%...on paper. Of course there are lots of reasons why we don't use half hitches generally.

Now, the main point I would make is that lots of knots could be "trusted" for rigging drops. I could tie 12 granny knots in a row and heck, they would probably hold. But *should* I?

Allan, your knot *might* be safe. You claim it has been so far and thats good. But It *might* not be, maybe you have just been lucky. But even if it will work 100% of the time, it is 100% for sure NOT the knot you SHOULD use for caving...ever.

Circumstances vary and some knots do better than others in certain cases. I could use many knots that would work. But I only know a very few knots very well, so my advice to you, that I follow myself, is to use a figure 8 with tensionless wrap when you can, a figure 8 and locking biner to a solid set anchor/s if you have to. I cant tie a Butterfly or Frost Knot on my best day anymore...heck I wouldn't even recognize them if I saw them. But I can tie a figure 8 half-conscious and numb from cold without thinking about it and it will be right.
Last edited by wyandottecaver on Feb 10, 2009 8:10 pm, edited 1 time in total.
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Re: Possible new knot!

Postby Cody JW » Feb 10, 2009 8:06 pm

I too prefer the figure 8 on bight.I like it because it can be used as an end line or mid line knot.I normally use the 8 on bight , then a few wraps around the tree before going in the hole so the 8 never will never see tension.The end of the rope going in the hole I also use the 8 on bight because it is large and no way a rack or a figure 8 will pass it.Also use the 8 on bight for bolts.In my opinion the best all around knot, easy to untie after accepting weight.
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Re: Possible new knot!

Postby WVCaver2011 » Feb 10, 2009 8:44 pm

I agree that the Figure 8 knot is the best knot around for caving. I just thought I would
see about this knot I made. I must have misinterpreted what I read! Let me go back and reread it, He said that with this type of set up you would get something like 70% so, That's what I got out of it! Thanks for correcting me! :kewl:
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