When rigging a rope by a loop knot from one end...

Does anyone use a Fig9 in preference to a Fig8 loop knot ?

Doe anyone have any comments on fig9 vs fig8 - I am reliably informed that the fig9 is more robust under rough handling than the fig8.

Anyone have any experiences here or comments?

AFAIK fig nine is better for thin rope as it has a the rope doesn't have as tight bends, making it stronger than a fig 8. It may also be less of a bugger to undo after being loaded?

I may be wrong so please correct me if I'm mistaken!

Francis

Never used a fig9 loop, always stick with fig8 loops.. I believe a fig9 is a stronger knot although it is slightly bulkier - would that little bit of extra bulk make it marginally more prone to rubbing around the knot (obviously depending on the rigging) if it was treated roughly?

If it's going to have a big load on it, get a figure-9 in it. Personally not really fussed about whether the knots stronger or weaker (marginal difference in knot strength and my rope's all in good nick) but makes it much easier to undo.

JB said:

If it's going to have a big load on it, get a figure-9 in it. Personally not really fussed about whether the knots stronger or weaker (marginal difference in knot strength and my rope's all in good nick) but makes it much easier to undo.

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Exactly.

paul said:

JB said:

If it's going to have a big load on it, get a figure-9 in it. Personally not really fussed about whether the knots stronger or weaker (marginal difference in knot strength and my rope's all in good nick) but makes it much easier to undo.

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Exactly.

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Agree too, although the Fig-of-8 can be easier to undo in a weird sort of way because you can use one of the loops as a lever .. not sure that makes any sense in words though!

dunc said:

I believe a fig9 is a stronger knot although it is slightly bulkier - would that little bit of extra bulk make it marginally more prone to rubbing around the knot (obviously depending on the rigging) if it was treated roughly?

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Definitely. This is a reason often cited for using overhand knots on cowstails rather than the bulkier figures of 8 or 9.

My theory is.... keep is simple...  Keep the number of knot types you use to a minimum and stick to what everyone you're with knows.  Knot boffins might be very clever but if they've made a mistake tying their Mendip Half Tangled Double Hitch Thingy Wot Knot on the Bight who would know?  Folk are more comfortable swinging around on what they know and recognise.  Fig. 9's are stronger but not by much and to be honest I've never really found them to be any easier to undo than 8's...

Thanks all - about the sort of answer I expected.
Not planning to change what I do; fig8s  - but worth knowing it as a marginally better knot.
Thanks.

i know what a figure 8 is but whats a figure 9?

ditzy 24//7 said:

i know what a figure 8 is but whats a figure 9?

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It's a Fig of 8 with an extra half loop in it.

Twist the rope around as if for a Fig of 8 then rather than pushing the rope through to finish the knot, wrap it around another half turn, then push it through.

If you're not sure what I mean, do you know what an overhand loop is? If so a Fig of 8 is an extra half turn from an overhand, a Fig of 9 an extra half turn from a Fig of 8.

I think this probably makes for a very confusing read .. sorry!

nope sorry you have compleatly lost me there as i dont know what an overhand is.

Have a look at these:

A Figure of Nine:



An Overhand:

ok thanx damian i get what you mean now 

For what it is worth, Lyons Equipment did some work for HSE on ropes.  Their report can be found at http://www.hse.gov.uk/research/crr_pdf/2001/crr01364.pdf The interesting feature is that their tests on various knots by a simple "tensometer" which ran at 500 mm / minute extension recorded breakage at between 50 and 85% of rope manufactures' stated strength, see p17.  Crudely, the Fig 10 did better than a Fig 9 than Fig 8 than Bowline than overhand.  But I have always felt this data did not reflect the dynamic load that a knot sees in a fall.  Also given the variability in these tests, I do wonder if the statistics warrant saying one is better than another.

A theoretical investigation http://www.iop.org/EJ/article/1367-2630/3/1/310/nj1110.pdf (which backed its theory up by work on spaghetti) suggest that the first bend in the knot is the most stressed part.  That prediction is supported by my picture which shows a frame from a high speed camera test Jim Evans and myself did using a Fig 8 knot.  The frame shows the rope just after breaking with the lower end "falling" to the right (I was lazy and did not rotate the image) whilst the other end has just come out of the lower part of the knot.  Perhaps I should put a larger image some where so you can see a bit more easily.   

I tried playing around with a piece of rope I have lying around

The fig 9 on a bight as pictured below, looks quite nice and is noticeably easier to undo after being loaded than a fig 8 on a bight. Tried tying a fig 10 (yet another half turn around?) and it's ridiculously big and rope consuming. Has anybody ever heard of/seen/used a fig 10 for anything sensible before?

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Francis

Never seen a fig10 in action.
Would make a damned good heaving line knot though - better than your mate's camera bag!

One point though: Be careful calling that a fig-8 on the bight - it isn't.
I always call that a fig8 loop knot - because...

The F8OTB is a bit of a misnomer, technically it is a fig8 tied on a bight so the name seems right - but a 'true' F8OTB is a totally different knot, used to form a Y-hang much like the bowline on the bight but with a fig8 at its core instead of the bowline.

Dep said:

Never seen a fig10 in action.
Would make a damned good heaving line knot though - better than your mate's camera bag!

One point though: Be careful calling that a fig-8 on the bight - it isn't.
I always call that a fig8 loop knot - because...

The F8OTB is a bit of a misnomer, technically it is a fig8 tied on a bight so the name seems right - but a 'true' F8OTB is a totally different knot, used to form a Y-hang much like the bowline on the bight but with a fig8 at its core instead of the bowline.

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Looking at the number of tails exiting the knot on the left - i.e. 4 (and 2 on the right) then this *is* a fig 9 on the bight - to form a Y hang

It is tied in exactly the same way as these by putting the double rope through the hole, and looping the loop back over the knot.

I once had this argument with a bunch of climbers (I think they were) who were convinced there was no such thing as a figure 9.  I think the only real advantage over a figure eight is that it's easer to untie after it's been loaded.  Whether it's a stronger knot or not I wouldn't really like to say (or experience).

SamT said:

Dep said:

Never seen a fig10 in action.
Would make a damned good heaving line knot though - better than your mate's camera bag!

One point though: Be careful calling that a fig-8 on the bight - it isn't.
I always call that a fig8 loop knot - because...

The F8OTB is a bit of a misnomer, technically it is a fig8 tied on a bight so the name seems right - but a 'true' F8OTB is a totally different knot, used to form a Y-hang much like the bowline on the bight but with a fig8 at its core instead of the bowline.

Click to expand...

Looking at the number of tails exiting the knot on the left - i.e. 4 (and 2 on the right) then this *is* a fig 9 on the bight - to form a Y hang

Click to expand...

I'll get me coat...
I looked at the top picture less opbvious - must have been tired 2:00 am eyes!