The magic of 7/64" amsteel...

[MrCrumbles]

Nominal rating ~1000lb, significantly reduced by any sort of turn or knot by who knows how much, edging close to failure with who knows what dynamic loading and/or wear history, overstress from bad hang angle, non-chamfered hardware...

Amsteel has nominal rating of 1400lbs, that is 40% more than 2mm cord referred which is substantial. 14lbs is also 40% more than 10lbs which is also substantial. But there is nothing here that argues for why 1000lbs would not hold up in the normal case, lets call it 'regular hammock camping with a normally in-hammock-active person of median weight'. I do not say that it does, but there is nothing in your argument that says why it doesn't with logical, valid arguments built on facts - there is a lot of arguments of the type "/.../who knows what dynamic loading and/or wear history, overstress from bad hang angle, non-chamfered hardware/.../" that doesn't answer the question, it goes outside of it. Better safe than sorry is an argument, margins in order for theory to meet reality is good practice, but better safe than sorry is also an oil tanker anchor cable, and in that case the argument is not about taking the load but rather "it is heavy and I don't want to lug it". Me neither, but it is still a different question and an argument used to polster a weak argument in the case.

/.../ significantly reduced by any sort of turn or knot by who knows how much /.../

Reduced by knots is valid. "Significantly" I cannot see as anything else but a guess with a word signalling "scientific proof". Significance is something that you use as a measure in inferential statistics which leads us to the next question "where are those facts about how much it is reduced?" I am quite sure there are a bunch of studies not made by manufacturers who wants to stay on the right side of "better safe than sorry" by far or be sued. I am not an experimental physicist but they also go hammock camping, I am sure. And if not, can please someone with access to databases with papers concerning physics do a sweep?

I question the 7/64" amsteel 'religion' - 'do not question a Thruth so true it can't be untrue but we cannot explain why'. And now I also want to add '...and if you don't understand it by your own means you should stay out of hammocks, but still - we can't explain it'. I have also used 7/64" amsteel 20+ years ago in different 'crucial' applications (still working, not used in a garage door mind you) but that was because there wasn't much else to choose from then and the application went beyond my weight class wiggling in a piece of cloth. It worked (still works) and I can use it today but sure I am gonna question why. The category of argument "it is just the way it is", which a lot of the arguments I meet on the topic here is, just doesn't cut it. For being someone who advocates “If everybody is thinking alike, then somebody isn't thinking.” ~ Gen. George S Patton" in your signature I find that you think a lot like 'everyone else'. Just sayin'.

/.../ All to 'save' maybe 20 grams? /.../

Not on topic. I actually argued initially that I might be carrying more total weight in my kit.

I'm personally a huge advocate of UL, or at least very light if I can't squeeze my kit into the strict '10lb or less base weight' definition, but one has to appreciate and understand the ramifications of gear failure out on a trail, where it can be very, very inconvenient. While it's probably not going to kill you, it can lead to some miserable nights or a ruined trip. There are usually many other places in the pack to reduce weight by a few ounces here and there.

I agree with all that but it doesn't apply to the question and it is arguments more of an emotional nature. One could ask why those kind of arguments are used though.

BUT, experimentation is part of the fun, or not so fun, so have at it. However it's good to research and to understand what has come before and that most things have been tried and discarded for various valid reasons.

Not explaining the valid reasons. Still I get the feeling that this is more about telling the people they are wrong not adhering to The One Truth than do practice of Gen. George S Patton.

[MrCrumbles]

https://www.hammockforums.net/forum/...-it-suspension
https://www.hammockforums.net/forum/...mmock-finished!!
https://www.hammockforums.net/forum/...h-it!-Whoopies
https://www.hammockforums.net/forum/...-Results/page2

This horse has been beat dead several times, but feel free to beat it again.

Unfortunately I can only open the last link, but from what I see this concerns weight ratings of 600ibs and less, there are arguments of distrust (imagination, not physics) based on that - would those arguments differ with weight ratings of 1000lbs, that is 162% to 200% in comparison? I am speculating here but I dare to say that it would be worth to ask the question.

Now - what I see from that link is a problem with knots etc. not staying put - that is an issue. Be it because of zing-it itself or smaller diameter/less gripping surface, it is an issue. So the question would be to find out how to modify that. Different knots, longer brummels, clean the cord surface, whathaveyou and if there is no solution found - well 7/64" amsteel it is. Arguments proving my hypothesis wrong, based on facts/knots. Now we know it, we don't guess it. The 7/64" amsteel Truth demystified.

The 2mm cord referred holds more than 5 times my weight (no, don't run w the "angles"-ball now, I also did math in school), I totally agree with margins to meet reality. Scuba tanks are tested (in not america) for twice their pressure limit (nb, not until they explode) and that is quite arbitrary from a perspective. You choose a limit, I am underwater but this holds twice as much as the rating, that gives margin for scuffs and bumps and time and what not - I feel safe. If an agency (usually) finds that these margins are not enough due to different use, better testing eqp, whathaveyou or needs to be changed (higher or lower) due to new designs and/or materials, this is done. Carbon fiber tanks don't explode if overfilled in the general case, the air seeps out between the fibers, security margins change (actually even qualitatively in this case). Hypothetically new superfast supercooled filling systems emerges and now there is a risk for breaking - new limits of filling speed (new quality, not regular pressure ration) are put in place. New cords with smaller diameter but higher weight ratings emerge, they take the weight but do they work with the regular knots/splicing techniques? Guess or understand - that is the question.

[nanok]

you keep mentioning reason and scientific proof, but your responses to any arguments are always pointing to other peoples incompetence or lazyness. aside from being offensive (which i personally don't care about in the least, but others might), it is not constructive, and goes against your own statement of scientific inquiry.

questioning constructively is good, people here will tell you they had quite enough of my own challenges of the "accepted ways". but if you want a scientific model, you will need to build it, because it doesn't exist (yes, we made it to the moon, but we still don't have a proper model for how rope behaves. don't get me started). what i gave you is a rule of thumb which has been arrived at through empirical experimentation (and no small amount of injuries and deaths in our history of using ropes for critical applications), most of it can be justified scientifically, but this is not the place to make a civil engineering crash course. the term often used is "wll" (working load limit), and it is commonly associated with a factor of 5.

going back to your dissent regarding statements like "knots reduce strength", and the vagueness of it: i agree, but you have a lot of work to do if you want that to change (meaningful work, if you chose to pursue it). empirically, we know that dyneema has shattered the old rules of thumb, both in terms of how slippery it is (knots known to be safe slip at trivial loads), but also in terms of strength reduction (some knots are known to break, not slide, below 20% iirc). for now, if you want to explore this seriously and challenge the guidelines commonly followed, the first step will be to do your own break testing, in a controlled and repeatable manner, and go from there. no, "it works for me" is not good enough, you need to break stuff to know what's going on, and you need to do it multiple times, in a way which is repeatable and reproduceable for peer review. that's only the first step, the complicated part starts after (as i said, the physical and mathemathical model to describe how knoted rope behaves is, quite simply, missing entirely)

[TominMN]

...
Now - what I see from that link is a problem with knots etc. not staying put - that is an issue. Be it because of zing-it itself or smaller diameter/less gripping surface, it is an issue. So the question would be to find out how to modify that. Different knots, longer brummels, clean the cord surface, whathaveyou and if there is no solution found - well 7/64" amsteel it is. Arguments proving my hypothesis wrong, based on facts/knots. Now we know it, we don't guess it. The 7/64" amsteel Truth demystified.

...

Just a couple of things about knots and splicing possibly not holding.

First, UHMWPE is a fairly slippery substance; In sheet form it is used as artificial ice. Therefore, the fibers (dyneema and spectra, to name two) and the cordage made from them are fairly slick. Coatings are added to either increase or decrease friction depending on the targeted use of the cordage produced.

Amsteel, and its close relatives bear a coating that is intended to add friction. This will seem backwards to a lot of folks because these cords gain grip with a bit of wear. I believe it is about extremely fine fraying and not the fact that the coating wears off.

Gripping surface is a pretty minor factor, IMHO.

I think you meant "longer buries" and not "longer brummels." Locked Brummels aren't spliced at varying lengths. And multiple Brummels would be superfluous.

[nanok]

and you're being very "polite" here: fairly slippery aka "the only solid known to man of any practical use which has slightly lower coefficient of friction is PTFE" would be a more complete statement. so it is, for any practical purpose, as slippery as it gets, give or take a slight advantage to teflon.

[TominMN]

and you're being very "polite" here: fairly slippery ...

UHMWPE is (homonym for the structures that beavers build. hint: not "lodge.") slippery! Better?

[Phantom Grappler]

A hammock with its suspension at 30* angle of hang, will usually bear the weight of hammock camper on each end of hammock suspension.

If a hammock camper weighs 200 pounds, then his suspension set at 30* will bear his weight—200 pounds at each end.

Many times hammock campers use trees 20 feet apart instead of 15 feet apart. And they fail to raise tree attachment points high enough to maintain a 30* angle of hang. This is because the attachment points are now higher than they can comfortably reach. And their suspension might barely reach trees that are further apart.

So now the hammock camper has a shallower angle of hang. Their suspension might be tight and close to horizontal. There exist scientific tables that show the downward force on hammock suspension increases exponentially when there is a horizontal angle of hang. So now that 200 pound hammock camper can cause 400 pounds of downward force along his suspension with a shallow angle of hang.

This lessens a bit when hammock camper gets in hammock and suspension is sagged down a bit, making an angle of hang less flat, but still not 30*

I’ve forgotten the name of book of hammock camping that shows these mathematical and physics tables.

Amsteel that is 7/64 inch allows for a safety factor of between five and 10 times the weight of hammock campers weighing anywhere from 100 to 300 pounds, for their hammock suspensions.

The science is available, but you must do your homework—further study may be required.

Part science, part with safety in mind—covering most all possible ways a hammock camper might overstress his suspension at any given time.
And part to help deter civil lawsuits when a hammock suspension fails while camping and putting wild stresses on their hammock suspension, that will not be mentioned when a civil lawsuit is filed.

There are multiple YouTube videos showing stress testing of amsteel and other ropes, using knots and various hardware. With some knots the amsteel’s breaking strength can be close to half breaking strength of amsteel that is secured in recommended methods.

There are hammock campers that use suspensions that are somewhat less strong than 7/64 amsteel. Sometimes their suspensions perform perfectly, and some snap in two while hammock camper is a long way from civilization.

If your hammock suspension works for you, then it works for you. That’s part of the wonder of hammock camping. If you come to a group hang, you will see all sorts of hammocks, suspensions, tarps, quilts and pads, rigged in every imaginable way.

We don’t have hammock police, when you rig your hammock at a local group hang, whatever works for you is fantastic!

[cmc4free]

[MrCrumbles]

/.../Amsteel, and its close relatives bear a coating that is intended to add friction. This will seem backwards to a lot of folks because these cords gain grip with a bit of wear. I believe it is about extremely fine fraying and not the fact that the coating wears off.
Gripping surface is a pretty minor factor, IMHO.
/.../

By fraying the surface you increase gripping surface and thus friction, that is the whole idea. Friction surface is probably a better term. Compare to common practice in painting, work over a coat of paint with abrasive paper, the surface for the next coat of paint to hold on to/grip is now multiplied by the power of a gazillion.

Just looking at diameters a 2mm cord has a circumference of 2x3.14=6.28mm while 7/64" has a diameter of 2.77x3.14=8.69mm, that means 38.3% larger circumference - substantial. (NB, this does not factor in weave, surface treatments etc., it is only demonstrating the difference resulting from diameter, resulting in friction surface, resulting in ability to hold knots/splicing). There goes a lot more math into it but I say the point still stands, it explains why posts point out that using the cord a little removes slippery coating (if zing-it has one) and frays it, ergo it better holds the splicing/knots. The 2mm referred cord needs more than 5" length to obtain the same surface as 7/64" does at 4" . In knots where friction surfaces are considerable smaller than a bury - well it is no news that certain knots works only on cord w such and such diameter. Thus knots as problem is a valid argument. Longer buries, different knots, if there isn't any - fine, thicker it is.So, lets say we go thicker, based on referred 2mm cord we imagine a 10% thicker cord - 2.2mm, like the zing-it. Linear approximation (just linear and just approximation but for illustration) between 2mm 1000lbs to 7/64" 1400lbs weight rating it is slightly more than 50lbs/.1mm, so 2.2mm 100lbs higher weight rating, it has gone from 71% of 7/64" weight rating to 78,5%, a 10% increase from 2mm. As per circumference it has increased from 6.28mm to 6.91mm, 10%. Not much.

But compared to the 2.2mm zing-it the 2mm referred cord actually has the weight ratings that is used in this post from the last of the four links you referred to earlier. There are factors with angles etc but the takeaway is the same - he has used it for 6 years if only for "science reasons", but he has. It is not specified which dimension it is, he states the weight rating as 1000lbs, the post below points out that 2.2mm has 650 weight rating, it could be that there is actually a zing-it at 1000lbs, give him the benefit of the doubt, then that has larger diameter than 2.2mm. The 2mm cord I refer to has the 1000lb weight rating, it is thinner than 2.2mm and as stated earlier in the thread there are problems with sliding knots/splicing, this strengthens that weightwise 1000lbs is a non-issue. Now, we could push it a little, the guy has slept 6 years on 2.2mm 650lbs, well, weight wise it really works, I am not going to push it to 1.75mm - lets give him that benefit of the doubt and stay at 1000lbs. (see, I do not pushing things in 'my' direction, rather opposite I weaken my case)

A couple of posts further down it is pointed out that calculators don't do dynamics, well that strengthens even more that 1000lbs is not the issue.

Is it one data point? Yes, the others are "one hour a day for x time" and "a few nights", and doesn't fit in my book (notice I question my own hypothesis). At the same time IF he did 650lbs but thinking 1000lbs he could have trusted 1000lbs but never would have done it with 650, that being the reason why he happily has hanged for 6 years. At the same time he can be lying and a fraud, he actually never shows up in the thread after his post. (See, again I can critisise my own hypothesis)

I think you meant "longer buries" and not "longer brummels." Locked Brummels aren't spliced at varying lengths. And multiple Brummels would be superfluous.

You are quite right, buries it is. Autocorrect is not to blame.

[joe_guilbeau]

"Is it one data point? Yes, the others are "one hour a day for x time" and "a few nights", and doesn't fit in my book (notice I question my own hypothesis). At the same time IF he did 650lbs but thinking 1000lbs he could have trusted 1000lbs but never would have done it with 650, that being the reason why he happily has hanged for 6 years. At the same time he can be lying and a fraud, he actually never shows up in the thread after his post. (See, again I can critisise my own hypothesis)"

We all should take a moment to examine our objectives, we are a community, if you will, so we (the collective) should approach these discussions as if we are sitting across from each other in hammocks in the wild, after all, isn't that the objective?