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Hello,

I've never done a S/L jump. I have my eyes on this 200' object, pretty decent landing area but way too low for me to freefall. I plan to do some S/L jumps from another, taller, object to test the setup and then use it from 200'.

Instead of tying the break cord to the bridle or tying a loop in the bridle for a quick link, I'm thinking of rigging it like in the pictures attached (using a longer back up loop of break chord too). It'll load the bridle more like a PC would, at least that's what I think.

Anyone jumped with this setup? Good/bad idea? Am I going to kill myself?

/SC

There are many, many discussions about static line rigging in the forums (especially in Technical), as well as a good article in the Jumping section of the Articles. Search for them, and start reading and thinking.

This reading should be able to clarify what you need to consider, as well as explain to you why it's not such a great idea to tie your static line to the end of the bridle unless it's strictly necessary.

As a side question, whose idea was it to use the Rapide link to connect the pilot chute to the bridle? The traditional lark's head knot is used for a reason: it's secure and simple. The Rapide link adds unnecessary weight to your deployment system, and can be a potential snag point, not to mention something else you have to check every time you pack. It's actually much simpler to change pilot chutes with the lark's head than it is to find a wrench to undo the (properly tightened) Rapide link.

good?
bad?

the static line is the primary deployment method.
the pc is the back-up deployment method.

both are now dependent on the rapide link. you are introducing an additional single point of failure and thus adding additional risk.

the pc will also dangle very close to the tie off point. this can be a good thing, or a bad thing. it really depends on the object and the wind.

the anchor point is also at the end of the bridle, thus you must travel farther before activating your parachute. if you want to open as high as possible, that can be bad. again, much is object dependent. I thought the Apex folks tested s/l setups and discovered the odds of premature breakage increase with effective bridle length.

your health is at risk, so you get to make the call!
(but if I understand it correctly, I would not call it death-rigging.)

oh, and from an administrative viewpoint, I'm not convinced discussing how to make a 200' jump should be in the Beginner's forum!

I think I'll move this to Technical.

I did come across references to the Apex super bowl tests and people suggesting tying the bridle shorter. My problem with this is introducing a knot to the bridle. It's rated at 1000 lbs, so it would probably not matter, but having a higher anchor point just seems like a better idea to me. Of course, this presents problem of it's own. A dedicated S/L bridle with a proper attachment point would be even better, where a failure at the break cord attachment point before line stretch would still allow the PC to function, but I don't have that. I would however be interested in pictures of one (I've seen the dacron version in the articles and also something on a regular type 4 webbing bridle that looked like a dive loop).

A lark's head is not meant for loading the way a break cord loads it. If the lark's head is loaded from the PC, then I agree. The quick link is there to load the bridle evenly on a S/L jump the way a PC would load it during a normal deployment, as well as permitting the PC to work (unless the quick link or the bridle fails).

A break cord tied in through the lark's head might cause friction damage and/or load the bridle webbing unevenly since it's somewhat compressed by the knot. In a previous thread people suggested using a quick link to avoid damage to the bridle, either tied with a loop lower on the bridle or through the lark's head. But instead of doing this, why not skip the lark's head? If the bridle breaks the PC won't work either way. And the drop length can be adjusted by choosing a properly placed anchor on the object.
Yeah, it might not have been the best choice of words :)

True, but a bridle failure at the lark's head knot would yield the same results. Of course, now we can face both bridle failure and failure of the quick link but the overall strength should be higher unless it's rigged improperly. The risk of that happening is also a bit higher since the system is more complex, but only marginally.

Yes, I've seen references to this in previous posts. It would be interesting to see some numbers and a description of their setup. I havn't found this. If the anchor point was at the level of the jumper's feet and they then concluded that a bridle with the effective length of 7' made the premature breaking problems less, this would still be a longer drop than a 9' bridle anchored to the object at the level of the jumper's waist.

The weakest point in the system is of course the break cord, and the possibility of premature breakage is lowered by having as little slack as possible. The second weakest point should be the bridle, unless the quick link is open or w/e, and it's pretty damn strong.

I posted this here to get feedback, and I appreciate what has been written. It's always better to go with the methods used and thoroughly tested with time than trying to reinvent the wheel, so maybe I'll do that. However, I do see a potential problem with a bridle loaded the way it is in a traditional S/L setup with the break cord tied through the lark's head knot.

Anyone noted bridle wear during S/L jumps? Got pictures?

fwiw...

static line setups can be tested with relative ease. users have posted about testing things at home. it is the best way to instill confidence.

i suggest an overhand knot halftway down the bridle and attach the system to that. the bridle attachment loop on the end of the bridle has failed in the past from the dynamic shock load.

All,

I know I am preaching to the choir by saying this but it is always worth repeating. In any rapide link application on parachute gear, use ONLY genuine Maillon Rapide links. The identifying marks are hard as hell to see without magnification, but you need to look for them.

Here's what they look like: http://www.peguet.fr/gb/peguet-qualite-securite.html

I was with some friends jumping rounds from a 400 ft. wall into water and we had rigged one of the rigs without checking. One of the links failed. No injury resulted but it was a close call.

BTW, this is what a failed link looks like: http://gymnasticscoaching.com/new/wp-content/uploads/2011/06/quick-link-failure.jpg

Walt

There are many objects where tying off to a higher anchor point is either impractical or impossible for whatever reason.

I have good results tying an overhand loop in the bridle at whatever position gives me the best geometry, and using a Rapide link between this loop and the break cord. I haven't seen any wear on the bridle where the loop is tied in some 15-20 static line jumps.

Does the overhand knot reduce the strength of the bridle? Sure it does. Is it significant? I don't think it is. Even if the knot reduces the bridle strength by 50%, we are still talking 500lbs, which is more than the ~400lbs strength of your bridle attachment to the canopy. I have one bridle I use only for static lines that I inspect after every jump. Bridles are cheap enough that I will scrap it at the first sign of wear.

If you save the pins, you or someone with the appropriate equipment can use them to make another one.

Higher how?

Putting the anchor point closer to the rig reduces the shock load on the break cord when the container opens and/or the canopy extracts. This, in turn, reduces the chance of a premature break.

Why are you using a rapide link in there?

My static line rigging uses a 220 pound rated screw link _very much on purpose_. It's intended as a secondary point of failure in the event of an unexpected snag of the bridle or PC during the static line retrieval.

Using a full strength Rapide link would be counterproductive in the system I use.

What do you mean by "static line retrieval"?

Walt

Why?

I tend to try to build in a series of cheaper failsafe points before the bridle, with the intention of preserving the gear.

The time after the break cord separates, when the carry on cord is leaving the object, during which time the carry on cord retrieves the components of the static line system (the broken break cord, the screw link, and the carry on cord itself).

The potential exists that as the carry on cord is swinging free of the object, it can accidentally snag an obstruction somewhere behind the exit point.

There is also some potential that another part of the system could be snagged before that, either through wind action or incorrect rigging.

The intentional weak point at the screw link helps to protect the more expensive gear components from possible damage during some sort of snag incident.

What is the purpose of this system? Are you leaving something behind when you exit the object?

If you are leaving something behind (and presumably then returning to the exit to retrieve it), it would be simpler and faster to install the break cord between the bridle and the canopy.

If you are not intending to leave something behind, I am confused as to how your system retrieves the components. Can you elaborate?

Interesting. Has there ever been a snag with a CWY setup?

Walt

Yes. I have video of one from two angles. The bridle tore in half and the entire static line system, half the bridle and the PC stayed on the object. From the helmet cam video of the rigging, it looks correct. My best theory (which is supported by the outside video) is that the wind blew the PC and bridle back up and around the object so that the bridle loaded directly before the static line system ever loaded.

Can you post or share that video an was the static line setup attached to the larks head loop or a knot in the bridle?
IMO (and I'm too new to know better) this is much less likely when you attach the static line to the end of the bridle (with the PC) because the system will be in tension, even with just the weight or the PC/bridle before exit and there's no excess trailing behind it.

I use 350 pound lanyard to give the bridle and PC standoff from the object and then a 200 pound generic link to connect the break cord (only break cord routes around the anchor). In theory (and drop tests) break cord loops fail, then then link fails and finally the lanyard fails before the bridle loop.

A shorter bridle will give you maybe a 5' starting advantage over me and my standard 9' bridle and there's going to be at least that much variance in opening height or brake release surge. The difference is mostly mental unless you're doing super low, technical jumps. My lowest is only 160' and I don't feel the need to go much lower.

bridle length does not really matter. slack in the bridle does.

removing all slack from the bridle (while standing on the exit point) means small movements can pop pins. it also means the bridle (and more...) can drag across whatever you are standing on.

so, if you think this is good, what am I missing?

You don't shorten the bridle to gain altitude.

You shorten the bridle to reduce the shockload when the bridle first loads. If you've fallen 9', the instantaneous shock load is much greater than if you've fallen 5'.

As an experiment, try rigging up an anchor with break cord to a spring scale. Attach a 15 pound (or whatever) weight to the end of the system where the jumper would go. Drop the weight 3' onto the system. Now drop it 4'. Now drop it 5'. Continue in one foot increments until you reach 9'. See how much more force you generate at 9' than at 5'?

The 15 pound weight simulates the force required to open a shrivel flap, but you can adjust the weight to something else to simulate lifting the weight of the canopy (just weigh your canopy and use the appropriate weight for it).

Drop your weight 4' onto your system, and then drop it 9' onto your system. Remember that your system _fails_ if the break cord breaks with only the weight of the canopy (because your break cord has broken prematurely--before you hit line stretch).

The point of shortening the bridle is _not_ to get you open 4' higher. It's to reduce the chance of a premature breakage in your system.

I understand a shorter bridle to reduces the initial load. I use a second loop of break cord because I expect premature breakage with one loop (9' bridle x 11 lb canopy ~ 100 ft-lb of PE).

One loop and a 5' bridle...
Two+ loops and a 9' bridle...
Five loops and __' bridle?

Regardless of bridle length would you recommend attaching to the end or the middle of the bridle? If the SL is attached in the middle how do you secure the free-running end?

edit:
I don't know what I don't know. There's a huge possibility I'm wrong to the max.

I always attach to the bridle as close as possible to the rig, so that you have the minimum amount of shock load when you reach the end of the bridle.

I generally attach the static line system to an overhand loop in the bridle, although I do have some bridles with permanent (sewn in) attachment points at the right length for the bridge here (which I sometimes use when teaching static line).


I'm not sure I understand what you mean by the "free-running end." Do you mean the end of the bridle and the (still attached as a backup) pilot chute?

I generally just let the PC hang down below the exit point. If it is windy enough that it can blow around and create an entanglement danger I like to hold it between my knees, because when I exit my knees move apart, which means that I will "automatically" drop the PC at the moment of exit.

You can also use a tailgate rubber band to S fold the excess bridle for better control at exit. Mostly I haven't found this to be terribly necessary, but it's a good technique for some exit points.



I never use loops, as they double the breaking strength of the system. I always tie the break cord in a single strand, and I always use two strands of greatly different lengths, so that one backs the other up (and so that they load sequentially and do not double the breaking force).

how about this knot?
http://www.animatedknots.com/...ww.animatedknots.com

loop vs single strand of break cord:
methods that intend to leave nothing behind virtually MUST use a loop. these loops DO double the amount of force required to break the cord (while knots in the cord will weaken it).

so, jumpers should remember this...
- the only time to use a loop of break cord is when it passes around/through the anchor point.
- use a single strand of break cord when using some sort of lanyard to wrap around the anchor point. (Tom's preferred method)

looping a lanyard around the anchor, then using a loop of break cord will increase the force to break by a factor of 4. (so 80 lb break cord will require 320 lbs to break).

I too have seen:
- a pc get caught and torn apart
- a hangup that created substantial canopy damage before releasing
- a system that released by severing the bridle

it gets ugly quick. if in doubt, create a backyard test setup!

I have only done a few S/L jumps, but I was first taught to use 3 or 4 wraps of electrical tape. I'm still here. :) Not saying this is the best method, but my mentor is a solid dude.

BTW, this thread has been really helpful. Probably won't go back to electrical tape, but it seemed to work well.

Not at all.

My system leaves nothing and uses single strands. In fact, my experience is that with a loop, the broken break cord usually floats off into space, because it is not tied solidly on both ends. With a single strand, even the two broken halves of the break cord are retrieved with the system.

Although it's possible to create a system with a loop that also retrieves the broken cord, it requires a bit more creativity (the easiest way is to girth hitch the loop around to attach it to the retrieval cord).

The first method I learned was electrical tape.

The carry on method has two big advantages over tape:

1) It's substantially faster to set up at the exit point, reducing exposure to possible bust.

2) It leaves no trace on the object.

I used to use electrical tape untill I had a real close call and there's no way i'd touch the stuff now. Only thing that saved me was I landed in the side of a steep bank and slid down it breaking my fall. managed to limp away with just torn ankle ligaments and a bruised arse. My advise would be never to use it on something that is too low to freefall. Unless all the things are the same for each jump (taping point, temperature etc.) then it is too unpredictable to safely use.

so, are you saying you do not loop something around the structure?
that means you literally tie something to the structure? and leave something dangling from the structure?

really?
if so, I missed something!

(this is exactly why I hate this discussion. engineering students struggle to understand basic statics. users read these discussions and risk confusion. that can lead to serious safety issues.)

you stated you use a CWY system. most make these from a length of dacron. the dacron takes the abuse from the structure. at either end of the dacron are pieces of break cord. that way one end will break, and the length of dacron will be extracted by the other, unbroken side. the idea is to have the dacron remain attached to the bridle. if the dacron somehow remains bound to the structure the other piece of break cord gives out, the jumper has a normal deployment, and the dacron stays on the structure. this dacron is the "loop" in your system. any loop, no matter the material, will act like a pulley and require twice as much force to severe a piece of break cord. it is why you ought to use a single strand of break cord as a severable link.

so, did I get it wrong? where? how?

No. I'm saying I don't use a loop of break cord.

Looping the break cord doubles the strength of the cord to 160 pounds. If you have a retrieval system with two sides _and_ you loop the break cord you are quadrupling the breaking force to 320 pounds.

Using a loop of dacron and a single strand of break cord will keep the breaking force around 160 pounds.

By "loop" I mean a single strand with figure 8 loops tied at both ends so that it can be larksheaded to the lanyard. It looks like a loop, but it's open.

Thanks for the tip on the excess bridle too. I always attach to the end of the bridle and use a rubberband to control the slack. I've never tried attaching anywhere else but I've got something to try now.

On my CWY SL two strands of different lengths route around the anchor point and nothing else. The break cord strands are connected at both ends to a loop in the lanyard (with a link at one end for quick attachment). When the cord breaks, both ends are connected to the lanyard and come with me so nothing gets left behind. If you've seen ~tom's aka greenmachine static line its basically the same setup since I learned it from him and can't stop using it.

Sorry in advance, for a minor thread hijacking here...

If you do a single strand of break cord, what knot(s) have people here used to join break cord to their CWY / "carry on" cord?

regarding break cord loops, someone mentioned making a loop of break cord by joining the ends in a follow-through figure eight knot. Presumably on the theory that it distributes adverse forces over a greater length of cord.

Does anyone use a double fisherman's knot to join break cord? This is, after all, the "gold-standard" joining knot in technical ropework.

edit: "double fisherman's"

Can you post a picture of your setup please?

Yes.

In my opinion the technically correct knot to use is the double fisherman's. In the real world, it appears that any knot that will hold works well enough.

Are those strands of break cord?

I avoid routing break cord around the anchor point, because I've often seen anchor points that had sharp edges, and I worry that such an edge might cut into the break cord, causing a premature failure.

I routinely have students explain the method on video, so that when they go home they have the video of themselves to refer to.

Let me see if I can dig through the course video when I'm in the office tomorrow and find one that does a good job. Otherwise I'll try to create one, but fair warning that it might take a while as I'm pretty busy lately.

Yes, I try to find smooth anchors rather than worry about a higher test line unwrapping from the anchor, painted railings and ladders are easy to find around here.

I've snagged lines in other applications and prefer a clean getaway if I can get one.

I did a jump with another guy off an A with a crosswind, 5-10mph, that was causing the PC and excess bridal to go inside an appending structure on the tower. He used a similar method, except he held it in his hand and released after jumping. Before the canopy reached line stretch the PC and bridal was already inside the structure, where it would have been had he made no effort to control it. Luckily the bridal and PC only brushed against some steel tubing and did not snag. I went second, and after some time of trying to figure out how to better control the excess, I ended up larks heading a small rubber band to the structure and then placing a bite of my PC into the rubber band. I try now to always carry electric tape when i'm going to sl an A, and if the wind is blowing the excess near a snag hazard or out in front of me, I pull the bridal horizontally away from the the attachment point until its taught and tape it down near the PC with a single wrap.

I would never advise someone to hold the PC in their hand.

If you slip and fall off the exit point, your natural reflex will be to grab and clutch, and you may end up holding the PC tight, leading to a premature breakage, and you falling, unstable and with a closed container, from a SL height object.

I agree Tom, it looked really sketchy to me. My point however, is that holding the PC and excess bridal with your legs or your hands only controls it till you leave the object, while it needs to be controlled till the break chord releases.

tie your pc to the bridal as you use to then connect your conectorlink as you did on your pics.. and route the breakcord through the conector link.

No reasson to make it posible to make more erros..
i do guess you know how to use breakcord before atemting your jump.

The same could go for holding the pc and bridle between your knees, if you slip and twist as you fall you could wrap the bridle and pc around your legs?!

On falling, the natural human instinct is to grab or clutch with the hands. The natural instinct with the legs is to flail them apart.

The best solution is just not to do static line jumps in high winds.

Very true. However, as we all know, natural human instinct fails to hold true at times. It is not natural human instinct to jump off something that will kill you.

I took a few pictures of Tom A's Method.

2 separate single strands of Break Cord at different lengths attached to a quick link then looped around the object and connected to the loop in the bridle.

Break cord breaks at 80lbs then 80lbs again and quick link stays on the bridal and the Dacron line follows through the object with you.

When its windy out I usually just hold the PC in my hand behind my back under the container and let go as i exit.

Have you considered a scenario where after the break cord brakes, the dacron gets trapped to the object? That´s why I never girth hitch the SL directly to the bridle but attach it with secondary break cord in case of the SL device would get trapped to the object.

Yes, I have thought about that. i have seen another guy rig it like you said. I have not jumped an object to date that that was a concern so i havent done it that way.

but even so, I believe that if with Toms method if the Dacron was to be hung up then it would be the next weakest point and break.

with your method if the added break cord were to prematurely break on normal deployment then the whole system will fail. maybe adding a second break cord at a different length to back that up could remedy this? just a thought.

yeah; careful with that dacron attached to your bridle

theoretically, 160 lbs, but that will be reduced by knots, sharp corners, etc.

wrapping the red dacron line around, say, a handrail creates an effective pulley. thus, a 160 lb load from the bridle will load each half of the red dacron with the 80 lbs required to break the cord.

looping lines (break cord or lanyards) can cause the force required to break to grow dramatically above 80 lbs.

so are you saying that the set up in my picture would require 160 lbs of force twice to break?

Yes.

The components of the system are intended to break in order from least expensive to most expensive. The dacron is third in the failsafe order. In the event of a hangup, the components fail (assuming a fairly new bridle) in the order:

Break Cord ($.25): 160 pounds
1/8" Screw Link ($.75): 220 pounds
Dacron ($1): 900 pounds
Bridle ($15): 1100 pounds

Each of these components acts to insulate the next from damage in the event of a hangup. All of them will fail before the (far more expensive) bridle attachment point of the canopy.

In the event the dacron retrieval cord hangs up on the object, it will break and leave a section on the object. It's recommended that you retrieve this piece if at all possible after the jump, to reduce your visibility.

Attaching the dacron to the bridle with a double loop of break cord (breaking strength 320 pounds, cost $.50 or so) is an option, but I don't believe it's terribly necessary unless the difference in cost between the $.50 break cord and the $1 dacron is going to break your personal finances.

Correct. I had exactly that happen with Toms system. Deployed as normal, and it was only after the jump I realized what had happened. No damage to anything other than needing a new s/l system.

if you assume the standard statics model of an impossible "frictionless pulley," then it takes 160 lbs of force in the bridle to achieve 80 lbs at your piece of break cord, as depicted.

that all sounds great, but it might not work as planned.

I s/l'd a casino once and over-engineered the rigging. I screwed something up and can't say for sure what I did wrong, although I can speculate.

the end result was a spanwise tear across the width of the center cell, adjacent to the attachment point. the A, B, & C, attachment points on both sides of the center cell breaking off. the canopy spun nicely as I watched the building flash by. air passed through bottom skin vents and out the gaping hole on the top surface. the canopy did slow me down somewhat, but a solid PLF and a helmet limited my injuries to a handful of elbow stitches and some form of undiagnosed concussion/contusion.

the canopy required extensive repairs, but I'm STILL jumping the original bridle. thus, I would not count on bridle failure.

(rated strength is generally what another geeky engineer is comfortable guaranteeing. the actual strength can be significantly higher. the difference from rated to actual can be considered a liability CYA. this is one reason testing becomes important. my statistically insignificant, single event should give some pause.)

ps,

I have also witnessed another jumper s/l himself. he jumped well, the system loaded up, and the break cord broke. the red lanyard remained on the object.

it was yet another rigging error that proved inconsequential.

Are you comfortable with this reasoning up to the point that you would be comfortable to test this in live environment so to SL only with fixed dacron loop attached directly to the bridle? If you are certain that the dacron absolutely 100% will break first and cause no damage to the gear, there should be no problem with this?

Personally I would not be comfortable with this experiment and therefore I choose not to expose my gear to such stress even in the rare occasion that the dacron gets hung up. And therefore I use secondary break cord to attach the dacron SL to my bridle.


Maybe it's the question if the glass is half full or half empty but I see it from the point of view that the additional $.50 or so spent on every jump for the extra break cord does not break my personal finances so I choose to invest it for my personal comfort. :)

Not to discredit...but was told from a manf that the bridle attachment on the canopy is designed to rip off and maintain flight...at 400 pounds!

so was I.

the manufacturer was rather shocked as well. I still have the replaced, torn section at home.

BUT, you get yo choose who you believe. it is your health at risk.

It' not, actually.

It's your equipment at risk of damage.

The only time your health is at risk is if the static line breaks prematurely. Any time you sustain equipment damage it is _after_ the canopy is already at line stretch.

Yes. I've actually seen the static line system fail such that the bridle was directly looped around the object, and the bridle itself broke with no other damage to the canopy.



Yes. And I've actually had the dacron break without damage to the bridle or canopy, as well.

I have a large number of older rigs (for FJC's) and if you'd like, you're welcome to come and take one out to the bridge and tie the dacron directly to the object and give it a try. If I get a chance at some point I'll try to do it and film it for you.

Here is my 4 cents worth of opinion

1. Break Cord Strand--------- 80 pounds
2. Break Cord Loop---------- 160 pounds
3. Quick Link---------------- 180 pounds
4. Para-Cord---------------- 420 pounds
5. Dacron ------------------ 900 pounds
6. Canopy ----------------- 1000 pounds
7. Bridle ------------------- 1100 pounds
8. Risers ------------------4000 pounds

I have personally experienced items
one through six break during a jump.

Anyone ever have/watch 7 or 8 break?
If so please tell us how it happened.

Cool, short video of paracord breaking:
http://youtu.be/9yHmMVKX2FE

not to be a dick..but this is your theory right..and your at the bridge..why dont you save us the trouble and the money...give one of your students the camera to prove your theory...

that only makes sense right..if your going to preach it....

http://vimeo.com/26454479

I took your course in 07 and I highly respect your opinion. However, I just can't see the need to complicate the system, when you can attach directly to the object with break cord and leave no trace.

BTW, I am convinced that this system, at least sometimes, creates a lot more than 160lbs of force, prob due to friction. I say this because the majority of the few times that I did use a cwy system, I could really feel it take tension, and one time the opening felt worse on my back than a three second slider off jump.

Sometimes when you wrap the break cord directly around the object it routes across a sharp edge which can cause a premature break (before line stretch, usually at either shrivel flap loading or canopy extraction).

The whole point of using the dacron piece is to put something more cut resistant than break cord against the object.

If you have a smooth, rounded anchor point, there isn't really a reason to use anything other than a big loop of break cord, but unfortunately many exit points don't give us great options for anchor points.

Yes, pick me, pick me, I am raising my hand, pick me...

Actually, yes, at a legal bridge we set up a handful of SL setups to test how each worked, etc. We had a camera focused on the SL attachment so we could slo-mo play back the setup to see how it worked. Tom A was filming our contraption.

We were testing a "double SL" where two break cords would break in sequential order, so there would be redundancy to make sure the SL did not break prematurely, but the total load to break the SL would not increase as one would pop before the second.


So we made two bites in the bridle with overhand knots, about a foot apart, maybe 9 inchs. They both attached to SL break cords, so the first would load then break - then the second would load then break... The system was tested to make sure each break cord would load independently.

The first SL worked as planned. The second broke the bridle leaving the PC, knot, and break cord on the object and the jumper with half a bridle. The bridle broke at the knot.

It is hard to tell in the video if there was anything different in the second knot - some kind of spring loaded whiplash when the first broke, or just dumb luck, that caused it to break.

The bridle was rather new if I remember correctly.

Either way - it proves that a bridle can break - especially if it has a knot instead of a sewn SL attachment system - and that sometimes the component rated for the least strength can survive certain types of dynamic or static loads where the "stronger" item will fail with the same load.

yes sir. Bridles can break.

This had a single loop of 80lbs brakcord, but I believe the bridle snagged between the canopy and the knot. broke at the knot. It was quite an eerie feeling when I went to stash my canopy and felt the bridle end at 3ft past the attachment point.

I am quite certain that if not for the knot in the bridle I would have had the bridle attachment point ripped out of the canopy

Na, it will take 80 pounds (for each of the two lengths of cord) plus whatever friction is generated by the dacron on the object to break the cord. There will be 160 pounds of force on the object itself as 80 pounds from the bridle is opposed by 80 pounds from the break cord.

Since we're talking about static line rigging:

What works better for a NON carry away anchor? There is a 175' B that I've been PCA'd off a few times, but there is nowhere to attach a SL to.

I'd rather not drill into the roof to set an anchor, so I'm likely going to have to run some type of cord or cable out through the roof hatch and to the edge.

1) Steel cable or chain I suppose would be ideal, and I can make it happen, but it's cumbersome.

2) Tubular webbing. Easy to work with, but somewhat flexible

3) Static climbing rope, a little heavier and less flexible than webbing, but I think has less stretch.

The anchor needs to be at least 25 feet long, so I'm certain both the static rope and the webbing will have some stretch. How detrimental to the system is this?

we had a similar situation, but 30ft higher :) used a length of 550 cord. It's cheap, and doesn't look suspicions.

I know that the bridle is the least expensive part of your actual rig, but I still worry about damaging it on static line jumps with the knot that you put in it. It seems that when you weight the knot during the jump with a normal overhand knot it will stress the material of the bridal a little bit. In the past I have used a figure eight in the bridal, but noticed it was really hard to get out after a jump and so I started doing a figure eight with an extra half turn, it seems to have worked well with little damage to the bridal. Has anyone else experimented with the knots they use in their bridal on these static line jumps? Interested to see what you all have liked in the past.

Dacron works well. I've used it, but only needed about 8ft. to keep my bridal and pc from snagging the grating on the edge of a long line.

The bridle webbing costs under 40cents per ft and it takes under 15 mins to make a new bridle, even when re-using the old pins.

so I just wait till it wears out enough to scare me and make a new one :)

An alpine hitch has better stress distribution (if memory serves) and is easier to remove from the bridle than an overhand knot:

http://www.animatedknots.com/alpinebutterfly/

To get it apart you just "spread" the loop and it will begin to loosen.

Thanks I just experimented with this and it seems to work well. Tied one in some 550 cord and weighted the 550 almost to its breaking point with the help my car that I pulled on it with. I was able to wiggle the knot free without a lot of trouble, and the knot doesn't seem to have damaged the cord. I'll try this with an older bridle that I'm not going to use and see what I find out.

Why would you not have another bridle just for S/L? When I get comfortable with all the info I plan on having a seperate bridle with a SL ring in it....simple


15 bucks to guess?

That's fine if you're unpacked, but what if you're already packed?

I mean, I guess you're supposed to pack for the jump, but since I essentially always do lowish SD jumps, I almost always pack immediately after the jump so I'm ready to go at the drop of a hat.

yeah, i'm not always sure what the next adventure brings and which rig i'll grab to enjoy it...

so for me, swapping out bridles is the opposite of keeping it simple.

simple for me is tying a loop of breakcord to my bridle when necessary. simple as that.

also, it breaks at ~80lbs... i don't care how you tie it.

5 min switch out would be worth the piece of mind...undoing two pins and one larkshead.


Right tool for the right job...

but absoulute personal preference !

Perhaps this is a stupid question, but why do everyone use Dacron as their anchorpoint?
Is it because you "get it for free" or is there a reason why you want a very strong anchorpoint?

If the break cord is going to break at 80 pounds (or 160 if looped), why have the next failing part rated at 900 pounds?
Why not use Type II nylon cord rated at 400 pounds, or 500 pound Vectran line?
I mean in the case of the CWY gets snaged somewhere.

If the numbers are correct that GreenMachine wrote the canopy will "fail" at 1000 pounds.
If the canopy is a bit worn and the Dacron is made rated lower than it's actual break point you might have problems.

Even if the Type II would have 50% higher break point than what it's rated at, it would still fail before any other part.

Just to be clear I'm not beeing sarcastic or anything, I'm new to this and do not understand it.

Has to do with sharp edges at exit points. Slag left from welders would cut 900 pound like hot butter..

Anytime I open a packed rig I feel like I'm disturbing something I worked so carefully to preserve, but you're right it could be done, and it's totally personal preference.

i agree with the peace of mind part...

but, 5mins spent re-rigging a perfectly suitable tool is 60% of the time needed for me to spend at the bottom repacking for the next jump.

you are correct though, totally personal preference.

I see. Thanks.

Thats a good reason to use Dacron at the part that touches the object, but would it be a bad idea to use Type II or Vectran at the other end of it where you tie it to the bridle?
I don't like the idea of having my second part breaking so close to the important parts.
And having a quicklink would work. But I don't like them, metal is scary

I tend to use an overhand knot and then just replace the bridle when it looks like it is getting worn.

I have a couple bridles that have sewn attachment points (basically like another pin attachment but with no pin on it) and that seems to work pretty well.

No. You can use almost anything. I've used cheap yellow nylon rope from Home Depot before. It's probably actually a great idea to use something a bit weaker than 900 pound dacron. I started using 900 dacron because I had extra sitting around from replacing lower control lines, and then I just grabbed that spool when I was making a new cord. There's no real reason to use that if something else is more appropriate to your use, though.

I used Dacron because I have extra just sitting there. I use it as an extentsion of the object, and I want the object to be solid (or fairly strong), and keep all the weak links as close to myself and my set-up (Just myself preference and piece of mind).

I used a quicklink in between the break cord and dacron.

So you leave dacron and QL on object?

I was first shown a CWY setup during my
FJC using Dacron, later I substituted some
Para-Cord because it is cheaper, lighter,
and weaker.

I used to used to put a knot in the middle
of the bridle but heard about Tdog's bridle
break and instead started using the loop
on the end of the bridle near the PC.

Eventually I ordered a couple new bridles and
took one of the older ones, sewed a loop in
the middle reinforced with a green ribbon.

I S-fold the excess bridle between the bottom
pin and the loop and use a tailgate band to
hold it and do the same thing between the
loop and the PC.

Recently I took a new friend Jim out to Wanda.
His first jump there and low we decided to static
line. The tail wind kept putting the PC out in
the air so I borrowed Zach's trick.

I attached a rubber band to the antenna and
then put just a small bight of material at the
apex of my PC in it. Perfect.

I also have an older 42" vented PC that I tore
so it is dedicated for static line jumps, hence I
keep the PC and S/L Bridle together always.

If it is an easy day blaze object with time and
space to dick around, I just use break-cord
and tie off -- but for sketchy illegal objects
like 180 foot construction crane over re-bar
then I prepare a CWY using Para-Cord, two
strands of break-cord (redundancy), and a
cheap quick link for quick rigging and zero
trace of my presence.

Good thread guys

Oh, for the question about how do you rig
an anchor when your strong point is NOT
next to the exit: I have used dacron,
vinyl covered steel cable, and rope.

I've only done it once, and I did climb to the top of the long line retrieve it and went hand held later that night after repacking.

I s/l it the first time because it was my lowest at the time and felt better s/l it before going hand held.

carry along static line from asylum. Buy one, or steal the design and make your own. Super simple setup, you only use about 5 inches of static line, and it takes about as long to set up as it takes to tie a two knots. Leaves no trace, and ive used it probably 50 or so times on a wide variety of objects with great success.

I have my own cwy s/l setup that I've used quite often. The above situation I was talking about was a special situation in which I needed to tie off 8 ft away from the exit.

I didnt see it on their page.

Tom, would you care to elaborate on how your CWY broke and part of it remained on the railing of Ruby? BTW, I went back a couple of days later and it was still there so I made a couple of tail gates out of it

Not Tom, This is how I do all of my S/L set ups now. I use one piece of cord on everything from fat round rails to knife edges on ice shields. You dont leave anything behind, which personaly I don't think its gonna matter if you leave a piece of "string" laying around, it may not even stay at the exit point, it may get blown away never to be seen again. Personally I don't see what all the hype is about leaving a piece of "string" for the lay person to find is any way.

Has this ever been an issue? You think a tower worker sees a loop of dacron hanging somewhere and tells management to install cameras or something? I don't see what the big deal is about some dacron hanging off a tower. Our lower towers probably have dacron hanging off of each side (and have for years).

Has anyone ever had issues with this?

Gauleyguide and I jumped his awesome,
low, and unique object named Ruby. He
went first with a PCA. I went second with
a home-made CWY static line.

This was about two years ago when I was
trying out variations on the CWY, then still
made of dacron, I eventually switched to
para-cord for the aforementioned reasons.

The CWY broke I believe due to one of the
finger trapped legs of the Y being loaded
against the braid. Oh well, live and learn.

My PCA worked, My Static Line worked, and
as I recall it was me who walked away from
that jump

Ethics

the rules of conduct recognized in respect to a particular class of human actions or a particular group, culture, etc.: medical ethics


I too believe no one will care.....but WHO wants to find out? I was told to be a ninja.... Ill remain a ninja.... never seen or heard....just footprints.

Ok maybe heard..... sorry I slipped on the sign climbing in.... damn traffic signs are loud....

???
I agree with you, up to your conclusion. yes, there will be 160 lbs of force on the object. each side of the "pulley" will also contain 80 lbs of tension. BUT, both sides of the "pulley" are tied together and attached to the bridle. thus, the bridle must be applying all 160 lbs of tension.

put another way, if the object resists 160 lbs, but the bridle only applies 80 lbs, what is the source of the other 80 lbs of force?

agreed.
attachment points can fail as well, no matter what people think. (it might be rare.) if people wonder what can happen if the bridle snags, the CWY lanyard snags, etc. here are a couple pictures for the doubters.

as previously posted, this canopy suffered serious structural failure. the A, B, & C attachment points on either side of the center cell separated from the lower skin. nothing above the attachment point needed replacement.

for some reason, people insist this can't happen...

Oh yea That hurt like hell, didn't break anything, it just HURT like hell.

I don't know if i would want my nylon achorpoint be exposed to sun and weather for years before i use it.
I guess it will never get weaker than a break cord without showing very clear signs of it, but still....

Just give it a few hard tugs, no big deal. Of course these are freefallable objects that some more inexperienced jumpers prefer to s/l. So having it break prematurely wouldn't result in death. If I was jumping something down and dirty low I would tie off a new anchor. (but it would still stay up there till the next time I was there)

... " Just give it a few hard tugs, no big deal ".
-
On long homemade Anchors to make the distance to the exit-point .
Probably told this to someone before in the past but here it is again .

me & slim went to the top of Beacon Rock over in WA. to jump . Cliff exit is 414 ft. to impact .
Plenty high but with blind exit over a knob & with 1 landing area only & there is No outs even on a 180 if when you get to low .
We have Free fell it a few times . but the 'SAFE Bet' . is Hand-held or Static because you need to get the Heading no matter what . Or your fucked and @ minimum you will be limping & bleeding if you don't fly the primary LZ .

So we hiked up to the exit & saw something that made us cringe but laugh .
Laying there behind the exit was a hand-tied hodgepodge of crap for a Static-Line .
All tied together for few yards & made of electrician tape piece , Boot string , Binocular strap . string-line & then tied to a Bush for an Anchor . & Bush was pretty small/feeble & sparse to say the least .

We realized it was Weston there a day or 2 ahead of us . Doing a Solo jump .
He was ' Playing it SAFE ' Choosing the Static Deployment . Being that he was Jumping Solo & had to get the Heading .
but Distance on standing Exit to any Tie-off point was WAY more than 9-Ft. Bridal .
So he scrounged thew every item he had brought with him . Cut-up & Hand-tied hodgepodge pieces of crap all together to barely make distance to the Bush to tie-off . & feeble Bush was just growing out cracks in the Rock .
Disconnected his PC Off his Bridal so as not to be dragging on the rocks behind & accidental snag anything when Exiting .
Stretched Bridal out behind him . Connected Bridal to that scabbed Mess with Electricians tape wraps .
To then do his 'SAFE Bet ', standing Exit , Static line Jump .
.

Jeeeesus. Awesome.

That is awesome! Thanks for sharing!

I assume all the self proclaimed BASE Ninjas and upholders of BASE ethics check the exit point and the general area below for bits of broken break cord, broken elastic bands and tail gates.

I know it might be a really stupid question and that my drawing resembles a dick, but if you can look beyond that - wouldn't this set up be acceptable?
release force <80 lbs on the green cord, anchor is cow hitched and brought down by the long green cord. If the cow hitch doesn't release, the second break cord releases the jumper from the knot.

Yeah... the bridle will - just before the point of break cord failure - experience 160 pounds of force, as will the object the set-up is looped around due to the mechanical advantage of the system. However this 160 pounds of force is generated by 80 pounds of weight. The source of the "other 80 pounds of force" is mechanical advantage.

With that setup I belive both break cords will break.
When the first break cord pulls tension on the red/dacron it will tighten the loop and the second break cord will not be able to undo the knot.

You could try it on the ground and see what happens

I should try it on the ground, but I don't own any 80 lbs breaking cord and I'm not really planning on doing any SL anytime soon either. But I find the topic very interesting, I hope someone with the proper breaking cord will try it out. I think the odds for it to work are best if you use the wide type climbing sling, and if you put the sewn part on the front side of the knot, where you also attach the long breaking cord so that it doesn't snag.

Wouldn't the 80 lb of force required for it to release increase the chance of a premature break (before canopy line stretch) I thought a 160 lb system with two separate break cords (the one described by mr. Aiello) is better and more redundant. Anyway, the DexterBase system is the best one IMVHO.

edit: read the post by base689 (it has pics) http://www.basejumper.com/...atic%20line;#2878649

see, that's how little I know :( sorry for posting!

Bam! 1. in case of a hangup, the carry away part of the break cord breaks and you fly away gracefully.
2. Maybe adding a second bigger loop of break cord is a good idea))

And this is The Internet, everyone is free to post whatever they want

I think the pic above (with two loops of break cord at the "upper loop") is the best scenario.

160lbs of break force seems reasonable. BUT If it was too high...

I was thinking of a modified version of -rm's idea could be made out of an old riser. This would load a straight section of break cord, not a loop. It's also probably the most complicated CWY SL ever conceived







And then once the main cords broke:



Here are links because the images are so small:
http://i17.photobucket.com/...63/ctnewman3/SLA.gif

http://i17.photobucket.com/...63/ctnewman3/SLB.gif

http://i17.photobucket.com/...63/ctnewman3/SLC.gif

http://i17.photobucket.com/...3/ctnewman3/SL2A.gif

Or you could just use a loop of lighter weight break cord.

Before anyone asks it took me about 40 minutes to draw that...

Holy shit I'm sewing your setup right now, I'll let you know how it goes. I have an addiction to trying new things.
Btw, autocad, solidworks, or sketchup?

Autodesk Inventor.

Also, I can't tell if you're being sarcastic or not...

No, seriously, I just finished making Mark I. Using a 3 ring-ish release from climbing 'biners and Ty-8 I made for another experiment. It works! I wont post pics until Mark II though, because it looks so ugly

ps. I removed my trolling signature for this post so you believe me

Awesome. Haha. I think we share a lot of personality traits.

wow.
I haven't done any s/l yet but that looks pretty legit. quick to set up, just a carabiner/quick link clip and good to go. stealthy too.

Anyway, here's Mark II. Please don't judge me on my sewing skills, I don't think a home grade Pfaff was made to sew 4 layers of type 8 The setup is just like your cad drawing, but with a mechanical advantage system like on a 3 ring (to minimize stress on the double kevlar loop)





edit: Oh, and the break cord is represented by white electrical tape. And the DB's setup is still my favorite. Now to find some guinea pigs.. To the riggers: 20U or Sailrite? (mostly for container work)

It's totally wicked that you just made that! The addition of the second loop is certainly a good idea.

with the parts in your hand, how does it "feel"?

Is there a concern in the base community that the 160lb breaking force is too high? It's my understanding that it's not, but if it were this would be a "viable" solution to achieve an 80lb break load.

Did you not see pictures in this thread of bridles and canopys torn apart

True... but that was due to snags.

The "dexterbase" setup that uer16 posted will nearly eliminate snag damage. However, if it was desired to change the break force from 160 to 80, then you could use something like setup i posted...

While innovation is great, I am a firm believer in KISS.

Why complicate things ? How many times will you run into a situation where you cannot make do with a rapide link, a short-ish length of 550 cord and some 80lbs cord ?

It feels good, pointless, and overbuilt
On a side note, by attaching a single strand with two loops on the ends on the DB's system (the first pic I linked) the force required to break it will be 80 lbs.

But if it has loops on the end, isn't the loop holding the anchor "closed" trapping it to the object?

Whoops, yeah, you're right. it's 3AM brain not working..

If anyone has a S/L design they'd like to see tested on a high-strength pull tester, send me a PM. (I can provide some basic material like break cord and bridle nylon)

These SL CWY designs are getting so much more complicated and therefore better! I can't see why anyone would listen to wwarped and simplify to avoid canopy damage which is not possible, despite any evidence wwarped might present.

Won't that much weight on both sides of the SL setup cause both break points to snap?

In 2007 I was started BASE, for the 2nd time,
with only 7 jumps under my belt and 3+ hours
away from the closest BASE jumper who is/was
not very active due to family, kid, business.

So I did/do a fair amount of low solos and
as such have done a lot of static line jumps.
I tested each design in my back yard with a
20 pound dumb-bell.

I wanted a set-up that could hold the load
if I gently applied it but would easily snap
if I tossed the same weight just a few inches.

Just in case any one is clueless, an object
that has inertia will apply more force due
to the laws of physics -- static vs. dynamic.

After lots of testing on the ground and on
the local freestanders I decided: that for
easy day blazers just use some break cord,
rubber bands to control the bridle, and a
small quick link if you want to pre-rig it.

For quick, dark stealth jumps from a 222'
building with tight, sketchy LZ then yeah
use a simple CWY static line set-up.

RE: the riser, 3-ring, over engineered thing.
Tons of fun for the mind and very creative
BUT heavy as shit and too much. Why do
you think PC's for SKY jumping collapse??

Nonetheless, keep thinking, having fun,
and sharing your ideas, hell you might
come up with the next new innovation
like Annie did with the tailgate, which
is simple, like the Russians using a
Pencil in space vs. USA's $10K pen.

amen

lowcountryBase shortened my post to all i should have said.




Yes it would. My point is that complicating things unnecessarily leads to errors. This is why the saying keep it simple stupid, KISS, exists.

All I'm trying to say is use two break lines rather than tying the anchor directly into the bridle, to avoid damage.

take TomA's setup, and attach it to your bridle with a LOOP of break cord.

per my calculations, the loop will require up to 320 lbs of bridle force to sever. the strands that are intended to break, should do so by 160 lbs of bridle load.

now if the CWY lanyard should catch and snag, one "frictionless pulley" is lost, and the loop of break cord will now give out by 160 lbs of bridle force. the system will simply function as if there had been 3 strands used, not 2.

(knots, friction, sharp edges, etc. will all have the potential of weakening any piece of breakcord.)

Ok, I have another suggestion if we're assuming the 160 lbs break force is desired:
take a climbing sling, and two break cords of different length. Prepare the break cords by making them into a loop using the double fish knot for instance. Lark's head the longer one onto the sling. Then, at the anchor, with the sling around the anchor, take the second shorter break cord and lark's head it into both loops of sling. Then, in case the sling is hung up for some reason, the longer break cord will also break at 160 lbs.

Are we doing all this instead of simply using a loop of break cord around the anchor to prevent premature release due to sharp edges?

so in this setup if everything goes as planned and the strands break and the CYA follows the system normally, what happens to the the Loop attached to the bridal in terms strength? does it now have a weakened strength? will it break at a lesser load now if reused?

I wondered that myself, but decided it didn't matter because

A) it's not life dependent, only site-stealth dependent
B) if the break cord is compromise to the point where it's only half of it's original strength, I doubt most CWY snag situations are going to be resolved by an extra 40lbs of pull force.

- I dislike giving advice. I've made enough mistakes and would prefer NOT sharing advice I later regret.

- after tearing up my parachute, I keep my rigging as simple as possible. I have never used any sort of lanyard since. gauleyguide and I appear to think similarly.

- people have many jumps on lanyards with "fixed" fail-safe loops. I bet there is a tremendous amount of experience out there, just not with me.

- read the other thread about forces required to deploy. the OP came up with a clever way to see how much force is required to extract and deploy his canopy. 80 lbs seems like overkill. 160 seems far more then necessary. try things out. s/l jumps will offer a much more "positive" force than a pc. I can feel the differences when I modify my rigging.

- low-timers involved in this thread are probably overthinking it (which can be rewarding, if you avoid gear fear anxiety!). most will s/l objects others freefall. if the pc is left on as a back-up, it should save you. only experienced jumpers should be considering the real low objects where this thread can really add value.

- it's best to develop confidence via experience, and not by reading the internet. I prefer reading stories of backyard testing. it's all too easy to mis-apply science when theorizing. surely someone could actually test setups from a C-182 as well...

For the record, I have a few <130 ft SL jumps, and simply used a loop of break cord tied around an anchor that was later removed. I don't think I'd ever use a setup like the thing I drew... But I like thinking about things like that...

backyard testing

YES 100%

test setups from a C-182

WTF

most will s/l objects others freefall

TRUE and in my not so humble opinion a
much better place than an airplane to try
out new S/L techniques, of course after
doing plenty of testing on the ground.

Maybe he meant an airplane parked on the edge of a 300' cliff.