fall factor calculator

Lazaruz can you explain how you you would accend a 80 foot climb on an srt system.Ived tried alot of different approaches and prefer footlocking a doubled rope system.Could a prusik with a great stretch potential stop the risk of injury associated with this technique.Ive tried footlocking on srt and it torks my knee,also tried the pantin and does about the same thing.Ive installed a pulley with a Srt with my primary climing line thru the pulley and dont really care to pull myself up sixty feet.i know alot of other options (mar bar,the frog system and so on)but expence is a factor and speed of instalation.I have alot of climbers working with me and they all seem to prefer the traditional methods of accention.It seems when i install an srt system i have to install it lower over a larger limbs and thus do not get as high as I need to.I often notice when climbing off an Srt floating crotch system the wind can really play havic and pull me more severely,especially in pecans with long limb walks.I do not like mechanical devices( ascenders)Do you have any advice because I do not want to put at risk me or my crew members.I really feel like the Srt tech Has some pratical purposes but should not be the only option.Does any boby have any data on injuries from droping on a prusik via footlocking ddbl rope.I just really prefer foolocking ddbl rope.Mark could you elaberate On the statement you made about precations in ones mental toolbox and also your views on how me and my guys can safely and effeciently get into the tree.Also Mark do you think footlocking on a ddbl with a prusik is a safe method.I learned alot watching Beddes over the years and I dont think I ever seen him ascend a tree without useing a prusik footlocking a ddbl rope
 
Its difficult Jimmy to explain here the fine points of setting up any sysem to work just right, which I'm sure you appreciate. Rich Hoffman did a great job of explaining his anchor bridge system, that must have taken ages with all the photos etc. I don't have re-sizing software or the time at the moment. I understand your findings - it took me a long process of elimination with all kinds of techniques and equipment to end up with a verson of the frog. Its very simple to set up. You should get a good idea from clicking here:

http://www.treemettlenexus.com/paolo.html

Look at the avatar - you'll see how its set up. Part of the slickness comes from the suitable harness attachment point, favoured by many industrial harnesses. So I included it in TreeFlex. We also incorporated a sliding bridge for efficient work positioning. A similar concept is available in the Petzl variobelt with sidestraps, if you can live with the back pad (actually the harness I'm wearing in the photo). There are ways of adapting arb harnesses for this technique, but they're a bit clumsy.

My right foot has a pantin, my left foot is in the footstrap. This keeps the rope taut for slick sliding through the croll. The karabiner at my waist is a Petzl Williams (broad and smooth nosed so doesn't snag the webbing attachment). I am attached to a Petzl ascension with a spelegyca (includes energy absorber) through the top holes of the ascension with Petzl am'ds. This is attached to the Williams with a 22kN maillon rapide. I don't like the ball locks but I like the shape and the smooth nose - I'll upgrade them to the triact versions. A footstrap is attached to the ascension for the left foot. It makes the legs articulate to the correct angle, and enables one or double footing against the stem.

There are a few subtle tips and tricks to ease of use. All will be revealed very clearly worldwide in the new year - if you can wait that long!

Its very encouraging that you are thinking about the health of your employees. Rather than applying it to all, work on the system yourself or a climber with a keen open mind, to sort it properly, then apply it to the crews.

As for the increased force at the top anchor, it depends how its done. I'm not even convinced that it is too much more anyway when figuring with the friction. maybe its something those with dynamometers can play with (anchor a chunk of wood on a sling though a drilled hole and attach it to a dynamometer. Run Access line over the wood, anchor it at the ground and load it to see the reaction force at the anchor). I seems safer to me alot of the time because one leg of the line can be run through several crotches, or along a leaning trunk. This dissipates force through several anchor points, or along the entire branch like a fishing rod. It doesn't matter, because you can proof load the anchor by hanging the entire crew off of it before you climb (all at the same time, just off the ground of course!)

As for safe footlocking, you could use an energy absorber, but you'll be stuck up there. Its a major problem with footlock methods - no quick rescue or descent, which is a problem if you get swarmed by bees/wasps to name but one instance.

TREEBING: Lets say a bolt or two are missing on a safety rail/cable of a via ferrata (Klettersteig). You are climbing the ladder clipped to the cable with a 1 metre sling. You slip and fall 5 metres to the bolt. You now have 5 metres of fall absorbed by 1 metre of lanyard. Now work out the fall factor and think about the force - scarey isn't it!
crazy.gif
 
actually his knot didn't fail. the rope came apart almost 25' above his last knot. as you said he left them exposed to the elements for quite sometime, while he was "temp. on inactive status", due to some parking tickets, or so i have read, but the rope did fail, not his knot
 
Firstly, the FF calculator is intended for dynamic ropes of rockclimbing and
the "static" ones associated with that & caving of a traditional construction,
I presume--e.g., Bluewater II, and not the truly "static" stuff.
Contrary some assertions above, yes, the FF really IS the key determinant of
force in a fall. In reality, there is some small advantage to short falls in that
the cushioning by the body is proportionately greater; but the length of rope
to absorb a short fall is little, hence the build-up. A key concern for climbers
and canyoneers and cavers who might tie in with some static ("daisey chain"
or HMPE sling) lanyard to an arm's length anchorage and then fall while having
reached above this point: big loads. This situation got some testing and
commentary in a 2006 Rock & Ice article by Duane Raleigh, IIRC.

Now I gotta believe, though, that there's a range of dynamicness for which
the FF is relavant and for less elastic materials it indeed is worse in long
falls. (Oh, also, I recall seeing plots of the forces for short & long falls on
dynamic ropes, and while the peaks were the same, the long fall sustained
high forces longer--which might have some practical significance.)

Surely if fall on say steel cable is worse the longer it is, 'cause there just isn't
any stretch to absorb what is undeniably a greater force!?

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As for [ QUOTE ]
As for the increased force at the top anchor, it depends how its done. I'm not even convinced that it is too much more anyway when figuring with the friction. maybe its something those with dynamometers can play with (anchor a chunk of wood on a sling though a drilled hole and attach it to a dynamometer. Run Access line over the wood, anchor it at the ground and load it to see the reaction force at the anchor). I seems safer to me alot of the time because one leg of the line can be run through several crotches, or along a leaning trunk. This dissipates force through several anchor points, ...

[/ QUOTE ]
If I understand this, you're suggesting that the friction of the support leg of
such a set-up will reduce top-anchor load, where the fallen load has no
such friction (drops straight down)? Rather, it should INCREASE the force at
the top, as the friction on the, er, belay side essentially shortens the rope
in the system a bit!?
(Unless, perhaps, the bit of dynamic belaying effect from such friction
gives more force absorption than would come from a static rope alone.)

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As for Dan Osman's failure, I posted information on that at
www.treebuzz.com/forum/showflat.php?Cat=&Board=UBB2&Number=64258&Searchpage=1&Main=54531&Words=osman&topic=&Search=true#Post64258
--it was a matter of FRICTION, not weathering, not knot weakness. And apparently
the frictional issue arose after an initial set-up was re-located/adjusted.

*kN*
 
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