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billit_proof
Aug 30, 2005, 2:20 PM
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does anyone have a pic, or link to a picture of how to tie a figure 8 with a barrel knot?
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tradmanclimbs
Aug 30, 2005, 2:40 PM
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I don't even know what a barrel knot is?
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chadnsc
Aug 30, 2005, 2:43 PM
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Could the original post be referring to a fisherman's knot?
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overlord
Aug 30, 2005, 2:47 PM
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i think hes refering to a know that looks kinda like half of the double fishermans, only a bit more twists on the rope. or if you can picture the hangmans know. something like that. it was originally used by monks at the ends of their cord belts so its sometimes named monks knot (at least that would be the translation from slovenian).
its mostly used as a stopper knot on the ends of the rope (its better than fig 8 for this purpose because it doesnt slide).
and i usually just back it up with a normal half knot. its about as good and tying takes less than half the time required for the barrel knot.
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shorty
Aug 30, 2005, 4:15 PM
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Contrary to popular folklore, a properly tied figure 8 knot for tying in does not need a "backup" knot.
Last fall I took an AMGA Top Rope Site Manager's course, taught by Alan Jolley (he's on AMGA's board of directors). Alan had just come back from Blue Water's factory, where they had tested various knots, slings, and protection to failure.
One of the tests was determining whether a figure 8 was stronger with a backup knot. It wasn't -- it made no difference. The backup knot (in theory) is for security, in case the figure 8 becomes untied.
So the next test was to untie the first bend of the figure 8 and pull the knot to failure (without a backup knot -- the loose tail now points towards the climber). Again, this "figure 7" partially untied knot did not fail. In all cases at Bluewater's factory, the rope failed at either the loop end of the rope (where the rope would contact the climber's harness) or a few inches forward of the knot itself. The knots were not the weak link in the system!
Of course, this is contrary to virtually everything I've been told through the years. But when Alan held up the strands of destroyed ropes and knots, it made a believer of me. It is my hope that someday soon this information will make it into mainstream climbing manuals and instruction.
In the AMGA course, we were taught that the backup knot was a necessity "back in the day", when climbers tied in with bowlines on stiff Goldline rope. Backup knots are still a good idea with bowlines even using modern kernmantle rope, but are not necessary with figure 8 knots on kernmantle ropes.
But I still sometimes use a backup knot when tying in with a figure 8, and Alan still laughs.
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macherry
Aug 30, 2005, 4:18 PM
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you can check my knot anytime shorty!!!!
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edge
Aug 30, 2005, 4:26 PM
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Shorty's profile pic: Do as I say, not as I do??? :lol:
http://www.rockclimbing.com/...p.cgi?Detailed=13344
Personally, I like looking down and seeing a double fisherman's as a backup. Old habits are hard to break, but from over 30 feet I break quite easily...
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ecjohnson
Aug 30, 2005, 4:29 PM
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Yeah, I was taught that you don't need a backup knot either. I was told however to make sure that the tail was double the length of the tied knot. so when the tail is doubled back over the knot, it doubles back twice essentially. That also keeps the tail relatively short and out of the way.
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shorty
Aug 30, 2005, 4:35 PM
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In reply to: Shorty's profile pic: Do as I say, not as I do??? :lol: Personally, I like looking down and seeing a double fisherman's as a backup. Old habits are hard to break, but from over 30 feet I break quite easily... |
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shorty
Aug 30, 2005, 4:41 PM
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In reply to: you can check my knot anytime shorty!!!!
Your other half will be out of town during this in-depth, 20-point inspection, won't he?
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badass
Aug 30, 2005, 4:57 PM
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Don't you think that if the rope broke near the knot in both cases that it would mean the most amount of force is generated close to the knot making it the weak point. :idea: :idea: :idea:
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tradmanclimbs
Aug 30, 2005, 5:07 PM
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I dislike a bakup knott on a figer 8. If the backup is in front of the knot it is too bulky. also the backup usualy loosens up and gets sloppy over the course of a day of climbing. just tie the figuer eight properly and tighten it up with a 4 in. or longer tail IT WILL NOT Fail. I use the Yos finish to keep it clean and keep the tail out of my way when clipping. the figuer eight is such a good knott that it still will hold even if it is only partialy tied.
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greenketch
Aug 30, 2005, 5:10 PM
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The rope broke at the knot because that is the weak point, not because more force is generated. The sharper the bend in the knot the greater the reduction in strength. In the classic anchor of a wrap three pull two it is bomber with a simple knot because most of the force is transfed to the anchor in the wraps before they reach the knot. The wraps are at a large diameter and so near full strength is achieved.
As to the OP a barrel knot is a half of a double fishermans. Only the Boy Scouts use this name to the best of my knowledge. If you look it up in Ashleys it is often called a "clinch knot" but that is only when it is used as a singular knot. As a backup it is half of a double fishermans.
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shorty
Aug 30, 2005, 5:40 PM
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In reply to: Don't you think that if the rope broke near the knot in both cases that it would mean the most amount of force is generated close to the knot making it the weak point.
When the ropes broke at the loop which would be going through the climber's harness (i.e. behind the knot), it was assumed that the pulling bar was bending the rope so tightly that this area became the weak point. But we don't tie into a single bar -- with most harnesses the tie in loop touches two wide sections of webbing, so in real life climbing this would not be expected to be a failure point. It was also felt that this breaking point in the test was far enough from the knot (5 to 6 inches), that the knot was not affecting the outcome.
Both Alan and Bluewater seemed a little uncertain about why the rope might break a few inches in front of the knot. I have always heard that bending a rope reduces its strength, with the tighter the knot producing the largest reduction in strength. I would think that the rope should have broken at the very front end of the knot, where the knot pinches down hardest on itself (which did occur with tests of knots in webbing). But the ropes broke forward of the knot, far enough away that they felt the knot was not affecting the outcome. We also thought that the rope might break on the pulling bar forward of the knot, but it didn't break there, either. There is a theory that dynamic ropes act differently than static webbing when it comes to the weakening effects of knot pinch points. Stay tuned for future results.
It is my understanding that more tests will be done to determine if these results were statistically accurate. However, we were told that tying a clean, well-dressed figure 8 knot (i.e. my profile picture), actually produces tighter bends in the rope than tying a messy figure 8. Bluewater's preliminary tests showed that the messy figure 8 was approximately 5% stronger than the well-dressed figure 8. My figure 8s are all messy now.
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slacklinejoe
Aug 30, 2005, 5:56 PM
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Interesting results. I would guess that the knot changes how readily the core can stretch inline somehow resulting in knot breaking away from the knot. Somehow I'm thinking "time" is entering into the equation for stretch / impact causing breakage since nylon will stretch. Obviously the guys at bluewater would know one hell of a lot more about the topic.
At any rate, I've always considered the backup knot unnecessary. I was taught - "if your relying on a backup on an 8, you've already screwed up".
I do however continue to put a backup knot, not to add some sort of strength to it, but to ensure that I leave long enough tails on my knots, and that those tails won't get in my damn way (more of an issue on TR / seconding).
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alpnclmbr1
Aug 30, 2005, 6:07 PM
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Moyer did test years ago that showed ropes breaking at places other than the knot.
The reason to tie a neat knot is to make sure that it is correctly tied. Another reason is that it is often easier to untie once it been loaded.
A 5% difference in a tie in knot is meaningless. The amount of force needed to break a tie in knot, is meaningless as well. (you would be dead way before the knot broke)
The main reason most people tie a back up knot is to get rid of the floppy tail of rope. I re-thread the tail or use a double overhand, depending on how serious I am.
A backup knot with a long tail is sloppy. A backup knot that is a distance from the tie in is worse.
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