Rope stuff

Nice, thanx!

i think specific application of a particular Friction Hitch giving slippage over an electrical line is a very good point as undesireable. But, then on the flipside; hitches with some slippage shouldn't be blindly thrown out if no such hazard under climber exists; and shock loading is the primary risk to minimize. Then the slippage can allow 'steam' or high pressure to escape the system on dynamic loading/ trimming the amount of force incurred by support, line tensile, other connections and climber's body etc.
 
I agree with you Spyder - slippage reduces fall forces. But the slippage was so small, you'd have to be way too close to the powerlines anyway. Working above live lines isn't general practice in the UK anymore anyway.

But the research appears to be done under perameters for fall arrest on single line. Arb work is work positioning on a doubled line. 50cm of slack is the most that would be out usually anyway. A case of trying to make a square peg fit a round hole - not a pragmatic way to resolve arborist issues.

4 feet of slack and a single line?!

I think I see whats happening here. It happened in the UK around 1993. The HSE was trying to squeeze arb into fall arrest. Which means full body harnesses and energy absorbers. The way around this, is to realise that if slack is kept to a minimum (50cm), only a factor 1 fall is likely, and so work positioning equipment can be used, which doesn't involve shock loading and associated energy absorbers/full harness.

In the tests I did on actual Arb doubled systems, there was no slippage to the systems from a 50cm drop (100kg test weight). The knot didn't fuse to the line either, and could be released easily. The down side, was 1000 - 1200kg anchor force (doubled rope = half energy absorption). Not much can be done about that, except avoiding slack in the system and not using such low stretch lines as double braids for work positioning (Ddrt).

The test does indicate how footlocking could raise concerns though, which is why I now access on SRT (no chance of a 4 foot fall).

Another issue is 22kN requirement WITH knots?! What the hell for? The Euro standard is 22kN full strength or 15kN with knots. Perfectly adequate. In fact, many IRATA technicians use ropes for life support with only a 10:1 safety factor, but they do have an additional redundant system just in case. They have excellent statistics to prove no rope failures.

I don't see that this research is accurate or helpful to arborists. Who was it done by? /forum/images/graemlins/confused.gif
 
Laz,

It was done by a split commitee of private sector (one business owner) public sector (Hydro One) and educational institution (one guy previously from Hydro). Basically 4-5 guys that havn't production climbed in decades, and when they did it was on tautlines and butt strap harnesses. One member of the team is familiar with some more modern techniques, however the whole team has a very strong bias AGAINST advanced climbing techniques. One member's direct quote "all climbers should be on the same harness, using the same rope, and the same techniques.....its safer" These are the people trying to legislate how I will perform my job. The length of slippage vs. hydro contact was an arguement made by one member of the commitee in a public setting of a few hundred arbos to belittle a younger guy who was argueing the benefit. It's a bull$hit arguement cause every operator of a bucket has a fancy energy absorbing lanyard that will drop a guy quite adequately into wires.

Thanks Kevin for posting that I'vbe been meaning to. I've got a couple pages already in comment to that document. Severly flawed. There are a number of different standards used as guidelines. Few or none of them are correctly interpreted for our needs.

The benefit is, if they over legislate then I'm gonna make a fortune as a contract climber. As the owner of my business I will do what I want. And that includes climbing with a energy absorbing VT and 11mm line. /forum/images/graemlins/avid.gif
 
They also like Tenex for Friction Hitch. i tell ya it grips good, high strength(5k in 3/8) and flatttens out to maintain more high strength and friction area. i like it in a (Sailor's) Gripping Hitch; but finish with backhand hitch. But what they call a Becket; i call a Buntline/Clove to self to form shrinking eye??

i'd think that unless you are over a fire pit or electric line; a little slip and elasticity to keep forces low on support, connections, bod etc. would be desireable. Especially in DdRT/ doubled line that is less elastic than mountaineering line that is used as a single line(doubled line; always less elastic than single line; becuase less load per leg of support in doubled). So, perhaps when the greatest risk is impact loading/fall; the slippier knots they toss out are better??

Great numbers on Scaffold/Dbl. Noose/ Double fisher persons. i like mine as an Anchor to self to form shrinking eye/turn not crossed. So lean more towards knudeNoggin's naming of Double Noose.

Single line tests would have more elasticity/ more weight per support line than our DdRT. Elasticity is gained when the SWL goes down. They are reciprocals like speed to power from same finite force amount. As you lose one to strategize with; you gain the other in trade. So, even more need for slip?
 
[ QUOTE ]
But what they call a Becket; i call a Buntline/Clove to self to form shrinking eye??

[/ QUOTE ]

'They' are Hydro one. The lead guy asked once; when questioned on the accuracy of the term Becket Bend (for the Buntline); 'How can 300 Hydro workers be wrong?' Didn't have an answer for him.....was a little bewildered as to how 300 Hydro One guys can swing such a big stick in the global realm of knot tying to rename a knot.
 
Spyder, I know what you mean about the benefits of hollow braid like Tenex. However, I wouldn't recommend it for tying friction hitches, as the braid thickness is thin and has no core for strength. That means easy to burn and bust with slippage/high speed descents. Thinking of what happened to Rupe in the ETCC, that type of slip would probably led to a fatality if using hollow braid.

Worse than this, some short spliced eye - eye lengths have the splice tucked back into the core. This has fooled many into thinking it is a load bearing core, rather than loose wadding to give a round cross section. /forum/images/graemlins/crazy.gif
 
Wow, another fantastic link to steal; thanx!

i only tie eyes; with a double noose/anchor to self. i'm pretty light and don't burn cords a lot. But, i also think that the loose weave and flatness might offer less insulation/ heat holding capacity and breathe more.

i especially like Tenex (not shown in pic, to give more dramatic color) when it is cord device for Icicle or it's similair brother Sailor Gripping Hitch.
 

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Your welcome Spyder. Big thanks to the Forestry Commision for funding the research, and Treevolution for contracting me to do it. For the record, I no longer work with Treevolution.

As for the hollow braid hitch, as long as you realise the dangers and limitations (which it sounds you obviuosly do), then I suppose its at your own risk.

But I can't say I'd be comfortable watching a trapeze artist do a 'no net' stunt thinking s/he had one..........!

I'm sure you get my drift. /forum/images/graemlins/grin.gif
 
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I thought a Becket Bend was the name for the hitch to secure and adjust a wire cored flipline to the harness hip D?

[/ QUOTE ]
Why? Though there's nothing formal, often Ashley's <u>ABOK</u> is regarded
as a standard for knots. It's often copied, though knots copying runs amiss at times
and then the mistakes are copied--incredible nonsense gets published!

[ QUOTE ]
I've got a couple pages already in comment to that document. Severely flawed. There are a number of different standards used as guidelines. Few or none of them are correctly interpreted for our needs.

[/ QUOTE ]

Here are some that I've noted, perhaps to supplement your comments.

0.) It bugs the @^$# out me that arborists, esp. it seems, and some others maybe (cavers?)
have chosen "Dbl/Trpl... Fisherman Knot" as a name for a noose hitch
using resp. Dbl./Trpl... Stangle knot. One more conflicting (mis)naming of knots.
And in this report, we have "&lt;misname&gt; tied in a loop" to cover what should be
simply "Dbl. Fisherman Knot"/"Trpl.Fish.Knot"; "Grapevine Bend" can enter here,
too.

1.) The Dbl &amp; Trpl Fisherman Knots are discordant--component Strangle (Dble
or Trpl Overhands) knots are of opposite handedness--, which is inferior in shape,
and uncommon; we can wonder, though, if the image is accurate of what THEY tested!

2) On p.17, the data for the noose hitches griped at above, has in each of three
tests, ONE with a knot failure and two w/o. Somehow "average" came out of this
but only for the Dble. But what does "DNF" mean, exactly? What load was sustained
(maybe only 50# more than where the one knot failed!) The strengths they derive
in percentage terms are "74/100/100"--heckuva range, there--25 %-pts!!???
Now, again, since we don't know the details behind the "DNF", we can only speculate.

3.) "Fig.8 on a Bight"--odd image for this, having a closed ring in the eye, which
means that the rope's ends MUST have been available (vs. tied in bight). Now,
maybe the ring got put on the rope, and then in fact the knot was TIB, but ... .

4.) "... knots ... when tie[d], dressed, and set properly"
One can see such admonitions, but seldom any instruction or image of what any
particular knot should look like when so tied! The image in this document for the
Fig.8 loopknot is typically unrealistic (which end is loaded, for starters?!).

*knudeNoggin*
 
i think fairly the differance betwixt cow and girth is if 1 or both ends are pulled as Standing Part, so easy confusion sometimes. But yes it does look like the end is spliced to self, so girth; nice catch!
 
[ QUOTE ]
[ QUOTE ]
I thought a Becket Bend was the name for the hitch to secure and adjust a wire cored flipline to the harness hip D?

[/ QUOTE ]
Why? Though there's nothing formal, often Ashley's <u>ABOK</u> is regarded
as a standard for knots. It's often copied, though knots copying runs amiss at times
and then the mistakes are copied--incredible nonsense gets published!


*knudeNoggin*

[/ QUOTE ]


Blair (p. 74 and p. 75) calls it a Becket Bend. But, although Blair makes reference to Ashley, he seems to have mis-read the reference.

Ashley (#1431 and #73) calls the form a Becket Hitch when it is used to tie the end of one rope to a becket "...which is generally an eye [of another rope] or a hook" (71, 72, 73). Ashley also states "It is sometimes called, in error, a Becket Bend" (#1431). See also #1887.

The mistake seems to be simply using 'bend' instead of 'hitch'. Do you have some other name for the knot?
 
Mahk,

Right! We did point that out, and all we got was, 'Well there's so many knots that are so similar, just use a picture'

So reduce communication to the level of those that painted stick men on cave walls to tell a story. I find that to be a lazy cop out. I and many of us here try to research and learn systemic, logical, proffesional methods of defining and communicating our systems and this lazy attitude on behalf of these 'astute', 'accomplished' BCMA's and Managers reeks of a superiority attitude that offends me. I am an arborist, yet I focus my energy towards taking what I learn and applying it to the trees with my own hands. I feel that the underemphasis and low opinion of what is required to climb and work trees by the members of these individuals, is a strategic manipulation in order to reduce the value of field workers in order to reduce payroll expenses, for both the private sector and for hydro one. And in turn overemphasize the value of the BCMA or Manager who has the same (maybe a bit more)knowledge, but choses or is physically restricted, from performing the work with their own hands.
 
[ QUOTE ]
i think fairly the differance betwixt cow and girth is if 1 or both ends are pulled as Standing Part, so easy confusion sometimes. But yes it does look like the end is spliced to self, so girth; nice catch!

[/ QUOTE ]

The difference is a cow hitch is made with the the end of a rope (and thus has a loose end that could slip). A girth hitch is made with a sling or loop of rope and is completely secure. See #1889 vs. #1890 respectively. If you really want to look at subtleties compare #1694, 1816, 1858, 1859 et al.

Ashley doesn't use the term 'girth hitch', but 'ring hitch' or 'bale sling hitch'. I don't know where the term girth hitch came in.
 
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