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WildWolf wrote:Since the Figure 9 knot is more efficient then why do most of us use a Figure 8 knot?
WildWolf wrote:Since the Figure 9 knot is more efficient then why do most of us use a Figure 8 knot?
Stridergdm wrote:WildWolf wrote:Since the Figure 9 knot is more efficient then why do most of us use a Figure 8 knot?
Define "effecient". Seriously, it's too open-ended of a term.
Once you can define that, you can better address you question.
Reminds me a of a recent right where I used a bowline and my fellow caver asked me why I didn't use a figure-8. Thought about it and realized, I didn't really have a good reason... and it didn't really matter.
But did make me think.
LifeOnALine wrote:Although a Figure-9 loop knot in the end of a rope, set and tightened correctly, is on average 10% stronger than a Figure-8 loop, in reality the strengths both vary by at least 10% each way, so there's only a benefit in terms of ease-to-untie
LifeOnALine wrote:The biggest 'problem' with the F9 is that it's only good as an end loop knot.
LifeOnALine wrote:and sure, a sewn eyelet is in theory 100%, but it don't help much if you want the knot 8 feet in from the end! I wouldn't be too happy on a pull-thru trip if each end of m'string had a fckn great bauble sewn on either....
ek wrote:The efficiency of a knot is a technical term that refers to the percentage of the original rope strength (i.e. the strength of a straight rope) that remains when the knot is tied in it.
However, as mentioned, the figure nine is more complex to tie and recognize, and generally the 10% strength difference doesn't matter because a sufficient safety factor is used. Also, the figure nine takes more rope to tie. I typically only use it on thin rope or when I want a knot that I can untie quickly.
10% stronger
If your knot strength matters to the last 10% you need a bigger rope.
The biggest 'problem' with the F9 is that it's only good as an end loop knot.
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I have used the figure nine on a bight as an endline loop and as a midline loop when it won't be weighted so that it will capsize ...
The directional F9 and the 'Bunny-9' do exist, but both are significantly weaker than the equivalent in the F8 family
An overhand is pretty much 50% at any speed ...
knudeNoggin wrote:But by one testing (Lyon Equip 2001) the Fig.10 loopknot is stronger yet, so why is the OP interested in the Fig.9 at all?
knudeNoggin wrote:I have used the figure nine on a bight as an endline loop and as a midline loop when it won't be weighted so that it will capsize ...
I don't see this: if anything, the offset loading of these knots favors the
Fig.9 for stability; the Fig.8 has a bad reputation from a presumed tragic
failing as an offset bend for abseil ropes and in testing as such.
knudeNoggin wrote:Indeed,
it's my belief that making a full turn before tucking out the end of the
*outer* of the twin ends of the infamous EDK (Offset Overhand Bend),
which effectively makes a Fig.9 in that line, gives stability to that bend.
knudeNoggin wrote:The directional F9 and the 'Bunny-9' do exist, but both are significantly weaker than the equivalent in the F8 family
I find it hard to believe that a Directional Fig.9 is weaker than a the DF8
qua loopknot;
knudeNoggin wrote:pulled end-to-end, the DF8 is essentially a Square knot,
knudeNoggin wrote:and the DF9 a more imbalanced structure. But there is a good deal
to consider re the orientation/dressing of such knots. Frankly, I'd think
that the Directional Fig.10 would work best--having a better through
loading structure, and being easier to untie. --dressing options . . .
WildWolf wrote:Since the Figure 9 knot is more efficient then why do most of us use a Figure 8 knot?
I wouldn't tie an overhand or a Figure 8 either when it would be loaded flat. (I would tie a retraced Figure 8 or Figure 9 around an object, so long as I was only pulling from the tail--this way, the knot would be kept set by the tail pulling out with greater force than the flat loading, and the knot would not capsize. I would not tie around an object with a flat overhand/Figure 8/Figure 9 bend and then clip into the loop.)
knudeNoggin wrote:Indeed,
it's my belief that making a full turn before tucking out the end of the
*outer* of the twin ends of the infamous EDK (Offset Overhand Bend),
which effectively makes a Fig.9 in that line, gives stability to that bend.
I don't think I understand what you're saying here. If you're saying that you think the Figure 9 [offset] bend is safer than the offset overhand [] bend, then I'm pretty sure you're mistaken. I can easily get an unset (loosely tied) Figure 8 or Figure 9 on a bight to capsize when I pull on the ends coming in, whereas it is much harder with the overhand on a bight. I think the overhand flat bend is the safest of the dangerous {offset} bends in that family because it is smallest--there is less room for capsizing.
knudeNoggin wrote:The directional F9 ...
knudeNoggin wrote:pulled end-to-end, the DF8 is essentially a Square knot,
I don't see this. (And the notion seems strange to me, as for instance, the directional Figure 8 pulled end-to-end jams, but the square knot doesn't.) Can you explain? Also, if this is the case, does it matter? As far as I know, the only problem with the square knot is that it slips--not that the rope breaks at too low a tension.
What does "imbalanced structure" mean? How does the "Figure 10" have a better "through loading structure"?
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