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Tree_wrangler
Feb 27, 2007, 5:46 PM
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Hi all,
I've been eyeing a large "amphitheatre-like" canyon for a Tyrolean traverse. Actually, I've got my eye on about 5 side canyons off the main river canyon.
Can anyone tell me what the maximum distance is for a Tyrolean? I.e., how many ropes can be safely joined from anchor to anchor? Some of the smaller canyons could probably be done with 1 or 2, but the real prize is pretty darn wide.
I have both static and dynamic lines. Right now, I'm assuming that I'll be weighting the static lines for traverse, and probably clipping into a dynamic backup, since I'm a family man.
Thanks in advance.
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majid_sabet
Feb 27, 2007, 6:36 PM
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How far apart are these two anchors ?
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Tree_wrangler
Feb 27, 2007, 6:56 PM
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Well, I'll be using large trees as my anchors or possibly a newly placed bolt anchor of my choosing. So what that means is that I can "cut the corner" of the amphitheatre to shorten the distance a great deal if need be. I.e., the canyon is narrower where the waterfall enters it and it continues to widen as it approaches the main river canyon.
For "the prize" though, at max distance, I'll take a WAG (Wild-Ass-Guess) that it might be as much as 800'. I can make the traverse less than that, but I'm hoping to set the lines at a maximum exposure (distance, height) while still maintaining a strong margin of safety.
If the physics of the operation allow for greater distance, I might set it longer, but the farther the traverse, the longer it will take to set it (days).
Does that help?
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majid_sabet
Feb 27, 2007, 7:32 PM
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800 feet ? did I see this correctly
are you setting it up as tyrolean" V " or a stright line 800 feet apart ?
how big is this tree ? what is the max load weight in the center of this 800 feet rope ?
how many ropes are you going to use for your main ?
(This post was edited by majid_sabet on Feb 27, 2007, 7:35 PM)
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deadhorse
Feb 27, 2007, 7:48 PM
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I've never done one with I joined ropes together but i guess it wouldn't weaken the system much... but it might be tricky to get past the knots when youre traversing.
I did a 150' in a similiar situation, it was a gorge with a mouth of a waterfall. You can buy static in huge single pieces (200m) so that might be the way to go. Have you figured out how you're going to run it? If it's wooded than you probably wont be able to hand-run the line to the far side. If that's the case, you need to be able to get to the bottom of the canyon, and also know how deep it is. My gorge was 150' wide, and 100 deep, and it took an extra 140' (total 290') to get the line up.
you can back up with dynamics, ( as long as you have them on both sides, but that's twice as much dynamic required as static. Also, if it does blow the static you'll A. be going for a REALLY long ride, B. Be in a precarious position in terms of escaping the system. Just make sure you got your bases covered. PM me if you want to know any of the specifics/pics of my tyro.
On top of being completely worthwhile, and one of the most memorable experiences of last year, it was without a doubt the scariest thing i have ever done.
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epoch
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Feb 27, 2007, 8:01 PM
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If you are really up to it, you can order an 800' to 1000' spool of both dynamic and static lines, so you won't have to pass a knot in your system. This would allow you a bunch of room to play with on many ideas.
I have a 600' spool tucked away at my parents place for a tyrolean near where they are at.
If you are really die-hard get some cable, then distance won't be as much a factor, though you'll need different hardware for the wire rope.
(To add my bit)
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Tree_wrangler
Feb 27, 2007, 9:03 PM
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In reply to: Have you figured out how you're going to run it? If it's wooded than you probably wont be able to hand-run the line to the far side. If that's the case, you need to be able to get to the bottom of the canyon, and also know how deep it is.
I had planned on walking the line along the rim, which would work for at least a short distance. But yes, it is wooded, and that will pose problems.
I've also got a compound bow with a fishing-reel attachment. You fire the line, follow it with thin perlon haul-cord, and then I can follow that with real rope. But, I can probably only fire it about 200-300', tops. Using it, it's possible that I could shoot and reshoot, to leapfrog the end of the line around the rim.
The depth of the "canyon" is 272' at it's shortest height (right under the falls). The canyon floor drops off rapidly as you move downslope. I've only got 4 60-70 meter static lines, and I can't afford more right this second, so I'll assume that I'm using what I've got.
In fact, I'll assume that I'm going to use the 2 New England static 1/2" lines that I've got. They probably have a working load of 10,000 lbs, but it might be as low as 7,000 lbs. I'm going to assume 7,000 to be on the safe side.
The plan is to straight-line it. I assume that the Tyrolean V decreases anchor loads, but that's not the plan right now.
As far as the dynamic back-up, I was planning on fixing that as a straight line as well, but without a static load on it unless the static line fails. I have a few options for clipping in to it....namely, I could use a biner/prusik or a pulley/prusik, or a Silent Partner, or a small Gibbs camming ascender. In theory, if the static line fails, then my weight loads the dynamic line without any significant shock, and I won't go for a ride.
Assuming I'm using two lines, then the two dynamic lines are both 10.5 mm. Let's assume they can both handle 7KN, which is less then they're actually rated. I have a third 9.8 mm dynamic line that could conceivably come into play, but I can't think of how....
(This post was edited by Tree_wrangler on Feb 27, 2007, 9:45 PM)
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Tree_wrangler
Feb 27, 2007, 9:09 PM
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In reply to: how big is this tree ?
I can choose virtually any tree I want, so long as the ropes reach and can be manipulated to that point. Knowing that, I'm hoping to use 4-5' diameter trees. Know, though, that tree size is only a moderate estimation of tree strength, so I'll pick a 2' tree over a 4' tree that shows potential evidence of heart-rot.
In any case, if I fix the rope around the tree at ground level, the forces I generate will be negligible to the tree (I won't be picking any little sticks).
Originally, I considered anchoring each end of the rope about 100' up a couple of old-growth trees. If I'm shortening the distance of the traverse significantly (like down to 180' or so), I may still do so.
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cintune
Feb 27, 2007, 9:12 PM
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A double cable rig is better than rope. Passing knots is a bitch. You own the land?
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majid_sabet
Feb 27, 2007, 9:44 PM
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cintune wrote: A double cable rig is better than rope. Passing knots is a bitch. You own the land?
If you ask any rigger, they will tell you that Tyrolean is most dangerous system of all and you must do your homework very well. First; you need some solid anchor, may be even backing few trees back to back. Your rope weight (assuming 11 mm static) for 800 footer will be near 60 lbs.
Having a pig in the middle of this 800 feet distance will put so much tensions on the anchors and every thing else in the middle especially your rope. You need some big MAMA JAMA 5:1+ rigging to take the slack of this 800 footer unless you are going to use the winch out of your jeep to pull.
If this was my job, I would buy steel cable spool (2 set) run them and use another two 800 footer dynamic for directional and tie them in the middle to your pulley and fix both 800 footer via 2 set of prussic to the different set of anchor. if for any reasons, sh*t hits the fan and main cable fails, your 4 prussic ( 2 on each side of the canyon)should lock the 2 dynamic rope but there is no grantee cause falling on 400 feet of dynamic rope ( x 30% stretch) you may deck if your vertical distance is only 250 feet.
Just do some calculation first or may be set up one from a shorter distance to see how it goes and play it safe.
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scrapedape
Feb 27, 2007, 10:48 PM
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Tree_wrangler, don't forget to account for the loss of strength due to your knots.
Majid, can you explain what you are saying any more clearly, please?
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majid_sabet
Feb 27, 2007, 11:09 PM
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scrapedape wrote: Tree_wrangler, don't forget to account for the loss of strength due to your knots. Majid, can you explain what you are saying any more clearly, please?
[URL=http://imageshack.us]
(This post was edited by majid_sabet on Feb 28, 2007, 8:39 AM)
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lemon_boy
Feb 27, 2007, 11:11 PM
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if i remember correctly, some dudes set up a tyrolean between castleton tower and the rectory back in the late 90's. that'd be a hell of a tyrolean.
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Tree_wrangler
Feb 27, 2007, 11:15 PM
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In reply to: Tree_wrangler, don't forget to account for the loss of strength due to your knots.
Good point. I won't.
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deadhorse
Feb 28, 2007, 12:19 AM
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I don't think you need to think TOO much about the reduction in strength inherited from joining ropes because it's not cumulative- whether you use one rope all the way across or 10, you've still got the strength reduction of the most obtrusive (and only that one) knot. Your going to knot with one line, so the strength reduction comes into play in both systems, and unless you REALLY know how to haul that slack it shouldnt be too bad.
What I was saying about taking a ride on the dynamic is trickier than that- It's the whole vector force table that comes into play with low angle 2 point anchors. you've got to calculate the angle your line will be with you on it (BEFORE doing it) to know how far you'd drop if the dynamic comes into play. you've got to get to 120 degrees before it's [only] 100% of your weight on each anchors (force is still doubled from vertical) and that's where 30% should happen.
A bow could help- but in my experience (my gorge was heavily wooded, right to the edge) It was impossible to walk the line to the other side.
I used that same petzl pulley that someone else showed, it's nice.
Have you decided what kind of rigging your going to use to tension the system? I'm not trying to underestimate you or anything- but on my comparatively small (150 across) tyro it took two people and a 'military transport knot' (i don't know the other name) to get it to an acceptable tension, and it was still a steep enough anlgle that it was hard to get off it. Think about making one side alot higher, and exiting on the opposite side of where you start.
I hope it comes together for you! we're all behind you
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deadhorse
Feb 28, 2007, 12:25 AM
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oh yeah, also- for some inspiration- remember osman's 1200 ft jump? his tyro was HUGE on that. It was a V tyro and he jugged out of it.
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al_piner
Feb 28, 2007, 12:58 AM
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cintune : It looks like someone is about to lose a finger in that picture !!!
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cintune
Feb 28, 2007, 1:11 AM
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Heh, that was just on the launch platform, no worries there.
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scrapedape
Feb 28, 2007, 1:38 AM
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majid_sabet wrote: scrapedape wrote: Tree_wrangler, don't forget to account for the loss of strength due to your knots. Majid, can you explain what you are saying any more clearly, please? Sure I could do that, just visit Tom's website and click on Highline Drop-Testing http://www.xmission.com/~tmoyer/testing/
Thanks. I was talking more about the specific rigging system you described, but the videos just show the general principle.
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majid_sabet
Feb 28, 2007, 2:14 AM
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scrapedape wrote: majid_sabet wrote: scrapedape wrote: Tree_wrangler, don't forget to account for the loss of strength due to your knots. Majid, can you explain what you are saying any more clearly, please? Sure I could do that, just visit Tom's website and click on Highline Drop-Testing http://www.xmission.com/~tmoyer/testing/ Thanks. I was talking more about the specific rigging system you described, but the videos just show the general principle.
I would love to see this tyrol that far via dynamic rope. personally, I do not think he would ever make it to the other side and it is going to be a major "V" with min 100 feet of drop.I am going to guess even with static , he would drop min 30 feet of more in the middle .
Any one else wants to guess on how far he would drop in the middle if he uses 800 feet of static ?
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cintune
Feb 28, 2007, 2:19 AM
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A significant one.
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majid_sabet
Feb 28, 2007, 2:21 AM
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cintune wrote: A significant one.
Is there any formula to calculate this ?
there has to be climber round here with PHD in math
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epoch
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Feb 28, 2007, 2:23 AM
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majid_sabet wrote: cintune wrote: A significant one. Is there any formula to calculate this ? there has to be climber round here with PHD in math
You don't have the answer to it??
*falls out of chair*
{BTW: I'm curious to see how the numbers go. I may even toss it around the office tomorrow and see if any of the geniuses have an answer, that is unless this is answered tonight.}
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cintune
Feb 28, 2007, 2:26 AM
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Variables include amount of friction, weight of climber, speed of traverse. I ain't figuring it out. I like cables, but if it's dynamic rope it's gonna stretch and form the V of death.
(This post was edited by cintune on Feb 28, 2007, 2:31 AM)
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epoch
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Feb 28, 2007, 2:29 AM
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The V of death equates to having ascenders handy...
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cintune
Feb 28, 2007, 2:35 AM
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And thinking about those anchors the whole time. More calculations.
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majid_sabet
Feb 28, 2007, 2:36 AM
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epoch wrote: The V of death equates to having ascenders handy...
seriously, is there a formula to calculate how much V on a 800 feet of static line ?
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cintune
Feb 28, 2007, 2:37 AM
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Of course.
(This post was edited by cintune on Feb 28, 2007, 2:38 AM)
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carabiner96
Feb 28, 2007, 3:31 AM
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majid_sabet wrote: epoch wrote: The V of death equates to having ascenders handy... seriously, is there a formula to calculate how much V on a 800 feet of static line ?
yeah, duh....you mean you don't know it? It's tattooed on the back of my hand.
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jakedatc
Feb 28, 2007, 3:44 AM
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seriously, Majidiot needs to know how long it will take him to get off that rope since well.. it may just give up on him!
Can't Google that one eh? hmm back to your accident searches then
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stymingersfink
Feb 28, 2007, 4:06 AM
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small side note:
be sure the pulley's you use for the traverse are rated for the type of rope you are using.
when I worked in a shop we had a customer who had set up a tyrolean using wire rope (steel cable), and subsequently ruined a ptezl pulley taking rides on it. not all pulley sheaves are rated for wire rope, and if you ultimately decide to utilize wire you will need to adjust your gear accordingly.
FWIW, sounds like it could be a ton of fun. I would suggest working out the issues with an arrow-launched pull-line... perhaps start with some 100lb test fishing line flaked in a rope bucket, use that to pull over some 5mm rope, then your actual working rope? Growing up I used to pull a 65lb martin lynx with an overdraw and 2413 x 24" arrows... with the right trajectory the sucker would launch 200+ yards with little effort.
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bbentley77
Feb 28, 2007, 4:13 AM
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What is the vertical distance from start to finish, how much drop? with 5 deg of sag in the system for 300 lbs (you plus rope ballpark), you need 3042 lbs of tension on the rope. Now whats the drop and I can figure it out more presisly from there. Or YOU can with simple trig. Tension on one side = (weight suspended/sin sag angle)/2
edit for number fuck
(This post was edited by bbentley77 on Feb 28, 2007, 4:31 AM)
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stymingersfink
Feb 28, 2007, 4:17 AM
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bbentley77 wrote: What is the vertical distance from start to finish, how much drop? with 3 deg of sag in the system for 300 lbs (you plus rope ballpark), you need 1721 lbs of tension on the rope. Now whats the drop and I can figure it out more presisly from there. Or YOU can with simple trig. Tension = (weight suspended/cos sag angle)/2
Bonus question:
with anchors 180degrees opposed how much tension would be held at each anchor?
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bbentley77
Feb 28, 2007, 4:20 AM
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i fucked the numbers at first. it would be 1721lbs on ea side (ea anchor). so 3442lbs total on the rope.
See attachment. (weight suspended/SIN sag angle)/2
(This post was edited by bbentley77 on Feb 28, 2007, 4:33 AM)
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sag.jpg
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rocknice2
Feb 28, 2007, 4:35 AM
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stymingersfink wrote: bbentley77 wrote: What is the vertical distance from start to finish, how much drop? with 3 deg of sag in the system for 300 lbs (you plus rope ballpark), you need 1721 lbs of tension on the rope. Now whats the drop and I can figure it out more presisly from there. Or YOU can with simple trig. Tension = (weight suspended/cos sag angle)/2 Bonus question: with anchors 180degrees opposed how much tension would be held at each anchor?
INFINITE
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stymingersfink
Feb 28, 2007, 4:47 AM
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rocknice2 wrote: stymingersfink wrote: bbentley77 wrote: What is the vertical distance from start to finish, how much drop? with 3 deg of sag in the system for 300 lbs (you plus rope ballpark), you need 1721 lbs of tension on the rope. Now whats the drop and I can figure it out more presisly from there. Or YOU can with simple trig. Tension = (weight suspended/cos sag angle)/2 Bonus question: with anchors 180degrees opposed how much tension would be held at each anchor? INFINITE
potentially, maybe... but in the real world never. the tension held at each anchor would not be able to exceed the failure tension of the rope.
i should have looked it up the angle/force multiplier table rather than put that question to the masses. i guess i was being lazy... my bad.
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bbentley77
Feb 28, 2007, 4:58 AM
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In reply to: i should have looked it up the angle/force multiplier table rather than put that question to the masses. i guess i was being lazy... my bad.
You didn't even need to do that. If two anchors are opposed and equalized with a pulley the tension on each anchor is always half the total tension.
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majid_sabet
Feb 28, 2007, 8:52 AM
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jakedatc wrote: seriously, Majidiot needs to know how long it will take him to get off that rope since well.. it may just give up on him! Can't Google that one eh? hmm back to your accident searches then
Why do not you go and climb , get some miles man , may be join the AMGA and become certified or some thing and make sure you post your cert next to your profile right below that 7 years of 30 feet tall rock climbing experience.
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epoch
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Feb 28, 2007, 12:32 PM
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We don't need a phd in math.
We need a bridge builder. Someone who lives and breathes catinary curves and can figure out the minute details. As a rough estimate you can use:
Total distance = d
rope stretch = s
(d/2) x (squareroot 2s) |
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jakedatc
Feb 28, 2007, 4:14 PM
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majid_sabet wrote: 7 years of 30 feet tall rock climbing experience.
and you'd be wrong again. I boulder, i do sport climbs of varying lengths.. i do multi pitch between 2-5+ pitches on trad..
and i don't WANT to be amga certified.. it has no use for me at the moment
i AM a certified athletic trainer which does put some validity on my posts in the Injury and Accidents forum on the post concerning peoples injuries.
and from your profile all i can see is that you're a troll and one day we will have our Kill File option back and you will be thankfully invisible
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majid_sabet
Feb 28, 2007, 6:02 PM
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jakedatc wrote: majid_sabet wrote: 7 years of 30 feet tall rock climbing experience. and you'd be wrong again. I boulder, i do sport climbs of varying lengths.. i do multi pitch between 2-5+ pitches on trad.. and i don't WANT to be amga certified.. it has no use for me at the moment i AM a certified athletic trainer which does put some validity on my posts in the Injury and Accidents forum on the post concerning peoples injuries. and from your profile all i can see is that you're a troll and one day we will have our Kill File option back and you will be thankfully invisible
Another 100 hour pilot who think he is qualified to fly jumbo jet . guess what, FAA just grounded you the permit to take off, just make sure you take a certified parachute with you, I do not want to see your qualified trainer's As* gets hurt out there on the real rock .
one more thing
Send an email to RC boss and request your Kill File
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bbentley77
Feb 28, 2007, 6:21 PM
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Distance isn't really a factor if you're using static rope as the rope will have to be heavily tensioned and probably at its max stretch or close to it in order to suspend an object. The only thing distance has to do with anything is the weight of the rope, which will add or subtract the total weight being suspended. What IS important is the vertical distance from start to finish. That will determine how much sag you can have in the system and still make it to the other side without getting stuck in the v.
Lets say the anchors are 800 ft apart, and the vertical distance (drop) is 40 ft.
tan-1(40ft/800ft)=2.86 deg of slope.
Now we know you can get away with 3 deg of sag in the system and still make it to the other side. Any less than 3 deg will require a shit load of tension, so if it's less than 3 deg, use cable.
Now 800ft of 11mm static is gonna weigh around 43 lbs so add your weight to that and we're at say 250 lbs total.
Now (250lbs / SIN(3deg)) / 2 = 2388lbs of tension on each anchor to suspend 250lbs at 3 deg of sag.
2388lbs * 2 = 4777lbs of total tension on the rope, the rope is rated at 9000 lbs, so you're ok.
You'll need a come-a-long or a chain fall rated at 2 or 3 tons to get that amount of tension, and don't forget to add their weight into the system. When tensionin the rope you'll need to hange while someone cranks to get the desired slop. Just the weight of the rope will take 2865 lbs of tension to have 1 deg of sag.
(This post was edited by bbentley77 on Feb 28, 2007, 6:34 PM)
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majid_sabet
Feb 28, 2007, 7:17 PM
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bbentley77
I have 2 sets of 600 footer 11 static and i know they are about 45 lbs each. I guess 800 feet should be about 60 lbs or so.The rope is rated at 9000 lbs without any knot, once you add the knot then you are in the 6000 lbs range.
If we use two sets of rope one on top with pulley as a backup and for whatever reason, main rope fails adding 1-2 second of fall factor in to the back up rope, how much force are we putting on the anchors or the rope, assuming our pig is 250lbs.
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epoch
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Feb 28, 2007, 8:04 PM
Post #45 of 58
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majid_sabet wrote: bbentley77 I have 2 sets of 600 footer 11 static and i know they are about 45 lbs each. I guess 800 feet should be about 60 lbs or so.The rope is rated at 9000 lbs without any knot, once you add the knot then you are in the 6000 lbs range. If we use two sets of rope one on top with pulley as a backup and for whatever reason, main rope fails adding 1-2 second of fall factor in to the back up rope, how much force are we putting on the anchors or the rope, assuming our pig is 250lbs.
Your diagram has you backing up your backup. Are you paranoid or something?
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bbentley77
Feb 28, 2007, 8:53 PM
Post #46 of 58
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If you're using a backup, it would be wise to run the lines close to each other and use 2 pulleys, one on each rope, matching tensions in both ropes so if one breaks, you're still on the other without falling. Each rope should be tensioned independently to obtain the desired sag of the setup. Once you start factoring shock forces into this system, tension is magnified greatly.
Lets say your setup lets you fall 2 ft before loading the backup system. Your backup tether is made of dynamic rope and a factor 2 fall of 2 ft for a 200 lb person = 12.64 kn. Now use the simple formula above, if your backup system were to hold at 3 deg of sag, the shock load would be 120.1 kn on each anchor, and 241.5kn on the backup line itself. So you can see that falling on this setup would be very unwise.
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bbentley77
Feb 28, 2007, 9:47 PM
Post #47 of 58
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One thing I would be interested in knowing is, if a rope is rated at 9000 lb, is that it's breaking point, or it's safety rating? I'm a pile butt by trade and do a lot of rigging on cranes. If a cable sling is rated at 10 tons, that is it's 5:1 safety rating, meaning that when pull tested, the sling failed at 50 tons. So if a rope is rated at 9000 lbs, is that it's breaking point, or is that is safety rating?
(This post was edited by bbentley77 on Feb 28, 2007, 9:48 PM)
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bmustaf
Feb 28, 2007, 10:41 PM
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It's usually it's 3 sigma rating. So, it's the average breaking point of the random test population minus 3 standard deviations.
So, no, it's not the same rating system you're used to :).
EDIT: Uh, I just forgot we were talking rope not hardware...ropes are a different animal. The most common rating you'll see in these is UIAA falls how many falls with a 9kN shock load the rope can handle before it should be retired.
There are other measures of course, but this is the one most people refer to.
(This post was edited by bmustaf on Feb 28, 2007, 10:50 PM)
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bbentley77
Feb 28, 2007, 11:06 PM
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Yes but static rope is rated at tensil strength, not for shock load. So maybe it is the 3 sigma? I guess I'll just write and ask.
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trenchdigger
Feb 28, 2007, 11:08 PM
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majid_sabet wrote: cintune wrote: A significant one. Is there any formula to calculate this ? there has to be climber round here with PHD in math
Actually most high-school geometry would be sufficient.
I'm frightened to ask how many highline systems you've taken part in the rigging of.
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majid_sabet
Feb 28, 2007, 11:45 PM
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bbentley77
beefing up the anchor is not a problem, we still got a biner that is rated for 30KN , unless we beef it up by putting 4 biner .
The whole thing could be suicide if it fails.
I forgot to tell you
My dad used to own near 50 Crane from 3 tons to big 150 ton Grove on the wheel. For 15 years I watched how they worked , interesting machines.
(This post was edited by majid_sabet on Feb 28, 2007, 11:52 PM)
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bmustaf
Feb 28, 2007, 11:59 PM
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I doubt it's the 3 sigma rating -- that's a hardware thing mostly (well, it's a statistics thing, but it's used mostly in hardware). My exposure to static line is all technical rescue so YMMV, but safety margins are not built into the ratings. The ratings are with they are, the limit. They leave calculating the safety margins up to the user. In our case (NFPA 1983), it's 10:1 -- that invariable requisites multiple belay lines, etc.
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bbentley77
Mar 1, 2007, 12:07 AM
Post #53 of 58
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In reply to: beefing up the anchor is not a problem, we still got a biner that is rated for 30KN , unless we beef it up by putting 4 biner . The whole thing could be suicide if it fails.
I don't think you understood. If you FELL on your backup you drew, it WOULD be suicide. You shouldn't FALL onto anything rigged up like this. I mean come on, even if the anchors would hold, there's no way in hell the rope would....??? 
(This post was edited by bbentley77 on Mar 1, 2007, 12:38 AM)
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majid_sabet
Mar 1, 2007, 6:03 AM
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bmustaf
Last time I checked NFPA was using 15:1 and most tech SAR used 10:1. May be NFPA gave up on those fat 5/8 fire ropes.
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bmustaf
Mar 1, 2007, 8:17 PM
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Yeah, you're right. I am a firefighter who also happens to be on a SAR (but don't do tech rescue in my fire job so I live with two standards, although we use NFPA 1983 for our personal bail out equipment).
SAR is usually 10:1 and you're right, NFPA 1983 is 15:1 for rope (but varies for stuff like biners, ascenders, etc). A lot of SAR has been moving to NFPA 1983, especially when the SAR is part of the FD, but in my area SAR is entirely separate from fire so they're still using their own SOGs (a lot of them totally homegrown and not bearing much relation to ASTM, NASAR, or NFPA -- which makes sense, because NFPA 1983 largely assumes an urban rescue scenario where 15:1 margins are easier to achieve with the resources available, where as in Rocky Mtn Natl Park we can't always muster a 15:1 ratio on a highline system).
(This post was edited by bmustaf on Mar 1, 2007, 8:26 PM)
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geezer
Nov 17, 2009, 8:12 PM
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bmustaf wrote: Yeah, you're right. I am a firefighter who also happens to be on a SAR (but don't do tech rescue in my fire job so I live with two standards, although we use NFPA 1983 for our personal bail out equipment). SAR is usually 10:1 and you're right, NFPA 1983 is 15:1 for rope (but varies for stuff like biners, ascenders, etc). A lot of SAR has been moving to NFPA 1983, especially when the SAR is part of the FD, but in my area SAR is entirely separate from fire so they're still using their own SOGs (a lot of them totally homegrown and not bearing much relation to ASTM, NASAR, or NFPA -- which makes sense, because NFPA 1983 largely assumes an urban rescue scenario where 15:1 margins are easier to achieve with the resources available, where as in Rocky Mtn Natl Park we can't always muster a 15:1 ratio on a highline system).
As a member of NFPA and a rope rescue tech, I am always curious when the "NFPA 15:1 Safety Factor" pops up in forums, discussions, seminars, etc.
If you do a search for "safety factor" in any of the latest rope-rescue-related NFPA Standards - 1670-09, 1006-08, and 1983-06, you will find NO reference to a 15:1 safety factor. You WILL find only a requirement for possessing "requisite knowledge of formulas needed to calculate safety factors for load distribution" and a definition for "System Safety Factor."
So, just where did this "15:1" thing come from? Here's the generally-accepted answer:
NFPA Standard 1983 says, "Okay, rope maker, if you wish to comply with our standard for General-use life safety rope, then you must weave it to withstand a pull of 40 kN (8992 lbf)." Furthermore, NFPA 1983 defines a design load of 2.67 kN (600 lbf). Divide 40 by 2.67 and voila - 15:1.
Remember that 1983 is a manufacturer's standard. Those of us in the technical rescue community who choose to comply to NFPA Standards, must follow 1670 for our squads and 1006 for us individually. But compliance with 1670 and 1006 does NOT mean that we rescuers must use "G" ropes for any type of rescue op. Nor are we compelled to design to a particular rescue load. Most Importantly, NFPA does not require us to apply a minimum safety factor of any particular value to our systems. If we wish to use "L" rated ropes and calculate our system safety factors to comply with our squad's SOGs, then, that is our choice. And, we may do so and still be in compliance with 1670 and 1006.
NFPA is only a standards organization with which our individual rescue squads may or may not choose to be in compliance.
But, just for fun, let's say that NFPA, instead, took on the role of Moses and commanded: "Thou shalt use 'G'-rated life rescue ropes, 15-to-1 minimum system safety factors, and 600-pound rescue loads!"
And off you go into the mountains on a rescue mission. The moment you tie the first knot in a "G" life rescue rope and load it to 600 lbf, you have now bumped your SF down to about 10:1 or so. And that, children of the rock, is why it's good to try to retain as much tensile strength as possible in your highline by tying no knots in it and rigging it only with a high-strength tie-off (tensionless) on one side and tandem prusiks on the other.
As Carl Sagen often signed off... "But, of course, I could be wrong."
RW
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rockforlife
Nov 17, 2009, 8:31 PM
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bmustaf's last log in, May 28, 2008, 10:05 PM
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majid_sabet
Nov 17, 2009, 9:30 PM
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geezer wrote: bmustaf wrote: Yeah, you're right. I am a firefighter who also happens to be on a SAR (but don't do tech rescue in my fire job so I live with two standards, although we use NFPA 1983 for our personal bail out equipment). SAR is usually 10:1 and you're right, NFPA 1983 is 15:1 for rope (but varies for stuff like biners, ascenders, etc). A lot of SAR has been moving to NFPA 1983, especially when the SAR is part of the FD, but in my area SAR is entirely separate from fire so they're still using their own SOGs (a lot of them totally homegrown and not bearing much relation to ASTM, NASAR, or NFPA -- which makes sense, because NFPA 1983 largely assumes an urban rescue scenario where 15:1 margins are easier to achieve with the resources available, where as in Rocky Mtn Natl Park we can't always muster a 15:1 ratio on a highline system). As a member of NFPA and a rope rescue tech, I am always curious when the "NFPA 15:1 Safety Factor" pops up in forums, discussions, seminars, etc. If you do a search for "safety factor" in any of the latest rope-rescue-related NFPA Standards - 1670-09, 1006-08, and 1983-06, you will find NO reference to a 15:1 safety factor. You WILL find only a requirement for possessing "requisite knowledge of formulas needed to calculate safety factors for load distribution" and a definition for "System Safety Factor." So, just where did this "15:1" thing come from? Here's the generally-accepted answer: NFPA Standard 1983 says, "Okay, rope maker, if you wish to comply with our standard for General-use life safety rope, then you must weave it to withstand a pull of 40 kN (8992 lbf)." Furthermore, NFPA 1983 defines a design load of 2.67 kN (600 lbf). Divide 40 by 2.67 and voila - 15:1. Remember that 1983 is a manufacturer's standard. Those of us in the technical rescue community who choose to comply to NFPA Standards, must follow 1670 for our squads and 1006 for us individually. But compliance with 1670 and 1006 does NOT mean that we rescuers must use "G" ropes for any type of rescue op. Nor are we compelled to design to a particular rescue load. Most Importantly, NFPA does not require us to apply a minimum safety factor of any particular value to our systems. If we wish to use "L" rated ropes and calculate our system safety factors to comply with our squad's SOGs, then, that is our choice. And, we may do so and still be in compliance with 1670 and 1006. NFPA is only a standards organization with which our individual rescue squads may or may not choose to be in compliance. But, just for fun, let's say that NFPA, instead, took on the role of Moses and commanded: "Thou shalt use 'G'-rated life rescue ropes, 15-to-1 minimum system safety factors, and 600-pound rescue loads!" And off you go into the mountains on a rescue mission. The moment you tie the first knot in a "G" life rescue rope and load it to 600 lbf, you have now bumped your SF down to about 10:1 or so. And that, children of the rock, is why it's good to try to retain as much tensile strength as possible in your highline by tying no knots in it and rigging it only with a high-strength tie-off (tensionless) on one side and tandem prusiks on the other. As Carl Sagen often signed off... "But, of course, I could be wrong." RW
NFPA is pretty common among the fire rescue or urban SAR but their standard is meaningless in wilderness SAR environment. Also, 10:1 SF is very common in mountain rescue.
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