Synthetic Rope Versus Cable for a Zip Line Install Purpose

Well there is synthetic fiber rope that is stronger than steel, it is susceptible to environmental damage though, and requires washing and protection from the sun....it works well in some applications, but a permanently mounted zip line wouldn't be one of them....it's also much more expensive....better to buy a zip line kit from a supplier...

http://www.amazon.com/Slackers-Value-Series-Zipline-Kit/dp/B00JRCGWZO

https://www.youtube.com/watch?v=gnM-hT3vr-c

Wow, lifting equipment always has the safety factor of 5 for lifting non-human load, i say greater factor for lifting human load, say if your lifting load is 100kg, you would select 500kg capacity rope to ensure safety.

Synthetic rope is used at approximately maximum 200kg lifting load, it wont be safer to use such on a human free fall speed rush equipment.

A zip line does not lift its load vertically; it must withstand several thousands of pounds of tension.

I agree. Something more like the . The lesser the angle the more the load on your ropes-see at 30deg angle you have doubled the load at the lifting point of your rope already. (Just reverse the pic configuration)

Following that diagram scheme, I wouldn't be surprised if the angle was 15, or 10, or even less.

Exactly.

F=1/(2*sin(θ)

Syntax error...

Sorry, compiler usually catches that.

3/8 " purple plasma rope has a tensile strength of 17,500 lbs....$3.35 per ft....It's not that the rope isn't strong enough, it's just expensive and vulnerable to wear in certain applications and conditions....It would work, no question....but for how long....

http://www.ropeinc.com/cat-new-england-spectra-poly3.html

http://www.engineeringtoolbox.com/wire-rope-strength-d_1518.html

It would be good (even necessary) to know the modulus of elasticity.

Thanks! Dyneema ~150,000; steel 29,000,000. An important difference.

Yup, Dyneema, that's what they make bowstrings out of... like I said.

But no one listens to poor ol' kitty Bwah Bwah.

Del

wassa factor of 200 between friends?

The strongest practical synthetic rope to use is called "Kermantle". Instead of twisted rope (three strand twisted to make one rope), braided rope (multiple strands braided in a round configuration) kermantle has a core of small strands whose mass exceeds the braided outer braided covering. Kermantle is the type of rope used for rock climbing, repelling, rescue, among other things. Kermantle is the strongest synthetic readily available but also the most expensive for comparable rope diameters. On a cost/strength basis it is about the same or less expensive. As a fireman I used to be certified in high angle rescue. Never used anything else besides kermantle.

Material of construction is also important. Nylon stretches but can be used as a shock absorber. Dacron doesn't stretch but this can be a benefit. Manila is trash. Kermantle is combination of synthetics.

Steel/strength is the cheapest but has no shock absorber properties. Stranded steel also creates small "burrs" on it that cuts hands, eyes, clothing, heads, arms, etc. Unless it is stainless steel it is also greatly effected by the elements.

Forget the cost of the cheaper rope or wire cables. It is no good for what you want. For the best safety use a kermantle rope. Would you want your family or yourself want to be the one that gets killed because the rope or cable failed? Also use good pulleys such as the Schaefer blocks used on sailboats. They are of stainless steel and/or very strong plastics.

Best thing to do is to a professional with skills in this type of apparatus and have them design a system and spec the materials. You have no business even thinking of what materials to use or how to set one up. Let the guy who knows what he is doing take on the design and probably construction of this. Money well spent!

At least in the table they spelled "kernmantle" correctly.

Most of those climbing ropes tend to be stretchy, as desirable for shock absorption in case of falling. All but fatal for zip-lines, though.

To all those proficient spellers-

Spelling was never my forte--not then, not now and not in the future! As long as you know what I mean that is satisfactory with me. Never knew how bad a speller I was not until I traveled through the halls of academia. Many more illustrious people can't spell well enough to get themselves kicked out of a bar, something I am proficient at (at least in my younger days). Why do I mention that? After a day of practicing repelling (going down) with Ke _ _ _?matel rope we would stop at the local gin mill for a couple of brews. At least we had a good reason to be there! Unfortunately this place had a brass "stripper pole" behind the bar" which tended to become our after repelling repelling pole. Out would come the prussic, the ropes, the carabineers, the harnesses and such. Being a married man I never did it, but some of the younger personnel would proceed to show the "dancers" how to properly repel down the pole. The ladies would always enjoy this display of technical ropemanship since the guys would always do a "safety pick-up" of the ladies as they descended down the pole.

OK, why did I spend all my time writing this? To prove to you that I can spell single and a few double syllable words. It really aint that bad! To err is human, to forgive divine!

Good Luck, Old Salt

The climbing maneuver is "rappel", not "repel". Sometimes spelling mistakes are meaningless; at other times they bespeak more serious mistakes, as in suggesting low-modulus fibers in situations where stretchiness is inappropriate.

To err is human, to forgive divine!

Proof that spelling isn't my forte. Thanks for pointing it out to me. I would rather do it than spell it. Have always been more of a hands on type of guy.

Good Luck, Old Salt

That is not responsive to the larger point.

Your comments are not clear to me and I can't find what you state is the bigger mistake. Perhaps this is because of the types of ropes we each use are different or perhaps because of the training and types of descending/climbing done.

Within the realm of recreational and some commercial boats, nylon is the preferred rope (line) for such things as anchor lines, dock lines, and situations where the shock absorbing properties are desired. Dacron is the most frequently used synthetic material for situations where elongation is an undesired property. This would include, but not limited to, halyards, jib sheets, main sheets, spinnaker sheets, genoa sheets, etc. For recreational water skiing a rope with an even greater elongation ability, such as poly, is most often used. There are many other materials used in ropes, it depends upon the task at hand. Sometimes more than one type of rope is suitable for the task.

For rappelling, as defined by Dictionary.com, the definition is:

1. noun (in mountaineering) the act or method of moving down a steep incline or past an overhang by means of a double rope secured above and placed around the body, usually under the left thigh and over the right shoulder, and paid out gradually in the descent. 2.verb (used without object), rappelled, rappelling. to descend by means of a rappel

In some cases, but not as often, it is used to denote also the ascending of a structure/mountain with similar but most often different equipment. For clarity purposes this is most often referred to as "ascending rappel" or "rappel ascending". When used in the context of high angle rescue "rappel" is most often used to denote descending and "ascending" alone to denote climbing or the upward vertical travel. As I have been trained and have always done, kernmantle rope is used for descending and ascending for rescue purposes. This is due to it's high strength per diameter compared to other types and because it has a low elongation compared to most other materials i.e. stretch is not wanted. To descend down a building, elongation would make spotting more difficult and could cause short term oscillation when stopping rapidly. This would be especially true when stopping at an intermediate level to transfer another person from the building or another rappelling line. As their weight is transferred to the rescuer, his line could stretch beyond a workable level to complete the transfer. Most often used is a "rescue 8" device in conjunction with other devices. A munter with a carabineer is often used if unexpected descent is necessary

For ascending, the same is true if prusiks are used. You don't want elongation.

Perhaps these are untrue for certain types of mountain climbing/descending but for rescue descending and most rescue ascending it is the most often used rope and methods.

A first responder would want the simplest, safest and most expedient methods for preparing to and to descend/ascend. For clarity first responders are almost always taught to say "ascending" to denote going up and "repelling" to go down. Since most rescues traverse from the top, pick up the rescued and then continue to descend this is appropriate.

In all my 100+ practice and emergency descents we have never been allowed to use anything but kernmantle because of its better properties than others for this purpose. (I no longer do it as frequently due to age and my wife's insistence)

Now is "That is not responsive to the larger point" still true?. Is "Sometimes spelling mistakes are meaningless; at other times they bespeak more serious mistakes" still applicable? The above dissertation is correct and true for boating and rescue rappelling. Nylon is good for my boat's anchor lines but not for my rappelling! Kernmantle is good for my rappelling but not for my jib halyards.

I still can't spell the greatest but I still believe in "To err is human, to forgive divine" even if it isn't me who has erred. Different equipment for different tasks!

Good Luck, Old Salt

Listening to yourself talk at ridiculous length is an acquired taste that no one else has acquired.

And some others have acquired a taste for personal attacks when their words aren't worth the short time to read them. It is all true but you didn't say it so it is all wrong. Come up with a better answer not worthless babble. Don't bother with another worthless attack to this. You could acquire a taste for saying short things with no worth, such as your last dismal attempt! If you can't beat them, shut up! Old Salt

Synthetic rope exposed to the elements will degrade faster. There will be more needed inspection and cleaning. Contaminates from the environment will get into the fibers. Where movement will cause them to abrade and cut the fibers. A good synthetic rope will cost more then steel wire. Out last the synthetic rope. Will not sag as much.

One thing that has not been mentioned: The two biggest enemies of synthetic fibers are sunlight (UV radiation) and Ozone. Rock climbers keep their climbing ropes protected in bags when not in actual use, and would never trust a rope or sling that has been left out in the elements for any length of time.

OMG! I just noticed that I just became a GURU Does that mean that now I actually know something about the subjects that I write about?

Not necessarily...

Congratulations!

Becoming a Guru simply means that you don't have a life.

Sometimes also denoted as a "Urug ginmalf dessa flah". (easier to read with a mirror).

Good Luck, Old Salt

You said, "I can't reward it with a good rating". Why not?

It seemed on topic to me. If you are referring to the fact that it had an OT rating, that's because old salt was referring to an OT response from you.

Anyone can voice an opinion about a response, as you have done. A vote is also possible, if you know how.

Would you advise someone to use a plastic rope for a zip line ride?

Would you put these kids on a 1/4 mile zip line made of plastic?

I would not.

Have you got a telephone? Then why aren't you talking to rope manufacturers instead of this forum?

With all due respect to other contributors, it must be remembered that this is a zip line installation. It is not a climbing, belaying, repelling, sailing, rigging or other type of application. Each material of the different ropes has it's unique properties. In fact some have more than one unique property. Some are good for one application but stink for others. Nylon, poly and some others have stretching as a property, good for some and bad for others. Dacron is synthetic with good UV, water and other properties but does not stretch much. This can be good and bad. Twisted ropes primarily come in the 3 or 4 strand semi round configuration. No good for a smooth or fast run on a zip line but great for running rigging and lines on boats.

Nylon has too much elongation since it can act differently for different weight people. This elongation also makes it difficult to climb up or down a rope if using prusik knots. Nylon same with polypropylene. Aramids (Kevlar) is available mostly in large sizes for tug boats.

What is the best? Either 1) Dacron with its good resistance to UV, water, elongation, etc. It is available in either a twisted or braided configuration, or 2) Kernmantle with it's UV and water resistant outer braid, strong inner fibers, resistance to stretching, smooth outer surface, etc. Each will be more expensive initially than some others but are stronger than others and will last longer. They will also give a better ride.

Not all synthetics will stretch a lot. Some are suitable for outdoor use with good UV, water and ozone and contaminant properties. Dacron or kernmantle are the best for zip lines. Inspection is no problem, just attach a rope to the end of the zip line and pull the zip line rope back through blocks to inspect it. After inspection just pull it back to its original position.

The best rope depends upon what you need!

http://www.animatedknots.com/rope2.php?LogoImage=LogoGrog.jpg&Website=www.animatedknots.com

http://www.gpjrope.com/ropespecs.htm

Good Luck, Old Salt

With all due respect, I don't suppose you've ever tried to string a 100# draw weight longbow with Dacron...

Trust me it stretches.

Del

I don't use longbows so I can't accurately reply (graduated to explosive charges). Have you ever tried to raise a 300 sq ft mainsail with a 100# draw weight string halyard? Likewise for the main sheet, jib sheet, jenoa, or spinnaker halyards and sheets. Dacron has its place as does longbow string. just as the stretch properties of nylon make them good mooring lines.

Good Luck, Old Salt

Ask a rope supplier. They have the expertise and are the logical people to advise you.

Your question is too simplistic to answer. As many in this forum have mentioned there are many synthetic. Some better sun resistance others stretch some don't. An answer can not be given. In the nicest way I would be consulting with a specialist, and he will ask for a lot more detail before suggesting any product over another. You will probably find short term saving equals future maintenance and if the maintenance is not done safety issues incur.

A more complex question than you would have first thought.

KONE Ultra Rope- replaces conventional steel cables with carbon fiber based light weight rope for elevators. This new material allows elevators to go without change over for more than 100 floors. You can visit their website to get details.

Since no one else has pointed out to the OP, that they should have done at least a little research before coming here asking for help to make a CHEAP, dangerous zip line, I'll offer the web sites below.

I'm sure insurance companies have an opinion about zip line construction, maintenance and operation also.

www.ziplinegear.com/

http://www.ziplinepro.com/home.html

Zip Line Construction Guide.

sharpstick try adding something constructive next time. Better yet, start your own forum and see how that goes for you.

EXCELLENT web sites. Wish I and many others had googled them earlier. We could have spoken more intelligently and not "redesigned the wheel zip line"!

Good Luck, Old Salt

I think this is impractical/dangerous for an amateur to do. What weight has to be supported? 250 lb? Someone suggested a safety factor of 5 for humans. That means to design for 1250 lb vertical. Then you have to look at the catenary equations to see how much the line tension increases as you limit the sag. Plus a synthetic rope is going to be stretchy compared to steel. You also have to consider the overturning moment on the support towers, or guy them to a large dead-end anchor. Not a good idea as plenty of others have said.

So why do you bother Lyn? The guy should be asking experts in the field via his rope supplier. Then he and I and you would not be subjected to all the bad grammar, bad spelling and balderdash that has spoilt this and many other discussions on this site.

I'm not sure why I bother.

Maybe it's a misguided desire to not empower others to unnecessarily put innocent people in jeopardy of losing their lives due to their incompetence.

As you see, many other well meaning members have empowered the OP with barely relevant, maybe even deadly, suggestions as to materials they have no experience with in this application.

I chose to be blunt/rude and tell it like it is.

I'd never give a blind man a loaded gun and tell him to fire away. Would you?

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This is off topic for the OP but not for the thread, lol:

>

OK, I didn't take time to read all the posts but here is my opinion.

The Zip-Line I had as a kid was a 1/4" galvanized wire rope or 7 mm to you Brits out there. It was strung between the City power pole 16" in dia and a pine tree of about 24" in dia. My dad worked for the city so using the pole wasn't an issue and the electrical wires were a good 12 feet higher than the Zip-Line.

Did we have fun on it. YES!!

Did we get hurt on it. YES!!

Did my dad finally take it down. YES!!

I don't think you have the technical skills to actually pull of a successful Zip-Line installation.

Seeing as you are posting this question on a public forum, I must warn you!! You are 100% responsible for anyone that is injured on the Zip-Line even if you do not allow them to access it. If they decide to ride it without your knowledge or blessing even if you are not present. Your homeowners insurance will probably quadruple! Or be cancelled!