Spectra, dacron, kevlar line discussion

[Daryl and Daryl]

Discussion of kite lines:

HERE

Not directly applicable to backpacking but interesting (at least to me) anyway.

[Jeremy Platt]

Thanks for the link Daryl, interesting reading.

Out of interest, what are the most important features for kite line? Tensile strength (TS)? If that is the case, wouldn't carbon fiber tow or something similar (highest TS to weight ratio) be the most common high performance line?

[Roger Caffin]

> what are the most important features for kite line?
Usually, wind drag. Then weight.

Cheers

[Jim Colten]

what are the most important features for kite line?
Usually, wind drag. Then weight.

Perhaps minimal stretch also? At least for steerable kites.

[Roger Caffin]

Hi Jim

> Perhaps minimal stretch also?
Well, maybe, but since all those modern synthetics don't have a real lot of stretch anyhow they probably don't even think about it.

Cheers

[James Cahill]

> "If that is the case, wouldn't carbon fiber tow or something similar (highest TS to weight ratio) be the most common high performance line? "

I may be completely wrong here, but in my experience with carbon fiber (weaves, tapes and tows) the individual strands don't always run the entire length of the tow, and may break when bent. This wouldn't lend itself well to applications with rolling/unrolling and any amount of bending (or even abrasion). I also cannot think of an application off the top of my head where the carbon fibers aren't embedded in a matrix of some sort.

So to your question, maybe line longevity, suppleness and handling? Just guesses.

[Jeremy Platt]

It seems that indeed carbon isn't great for line or rope. I just found this on a sailing site:

"Carbon Fiber:
First described in 1968, carbon fiber exhibits very high tensile strengths – but has not proved suitable to make rope: the high theoretical strength is lost during manufacture into rope and braiding has not proved satisfactory. It has been used as a high-tech sail fabric, to reinforce concrete, and in support stays for cranes and towers but not for the crane's running cables."

Sticking with sailing and unfortunately running a little off topic (sorry Daryl!), North Sails (who make cuben fiber), have fairly recently released a new fabric using carbon fiber as a reinforcement. Anybody tried this?

I was about to say it would would make a great tent/pack fabric, however it isn't as good with abrasion as kevlar. I was then going to suggest something reinforced with kevlar, but that is pretty much dyneema(?)

http://www.gizmag.com/north-sails-unfurls-game-changing-new-sail-technology/20832/

[Steve B]

I met a guy who worked at a company that made carbon fiber masts for yachts (world's cup stuff). I've flown kites since '89 and asked him about fabric. He said that carbon fiber fabric was the leading edge stuff, and this was during my '02 JMT hike.

Modern kite line has enabled modern kiting. Powerkiting (kitesurfing, buggies, etc) wouldn't be practical without spectra or kevlar lines. Possible, yes, as George Pocock rode a buggy to evade horse tolls back around 1800. Yes, it is the line drag and stretch.

Steve

[Roger Caffin]

I have an old 4WD Landcruiser with a winch on the front. I use the winch. It has a steel cable rated at 8,000 lb on the drum. The cable can get a bit curly, what with being wound on the drum all the time.

I am looking at a replacement car, to which I would need to add a new winch. The new winch would be 2013/2014 vintage: modern. It is not cheap. However, it is available with a Dyneema rope instead of steel for an extra $400. I have been assured that the Dyneema rope would be stronger (for its thickness), lighter and would not curl.

Sometimes, when I see people using Spectra and Dyneema tent guys rated at 200 – 400 lb, I do wonder whether they have ever thought about how much load their tent or tarp could take. Ryan's study on this Storm Resistance of Ultralight Shelters: Part 1, Introduction measured forces below 10 lb on the guy ropes in bad weather. Will Rietveld' study on Tent Stake Holding Power found that most stakes would only hold 40 – 60 lb loads in common soils. (5" stakes were awful, 6" stakes were fair, and 7" stakes were getting good.)

Me, I use a 0.6 mm Spectra kite line for my summer tent.

Cheers

[Bob Gross]

I just received a spool of this Dyneema braided cord. It is gray, less than 1mm in diameter, and supposedly holds 100 pounds. I cut off the first 100 feet from the spool, and it weighs roughly 6 grams. Yes, thread might be a better term than cord. The good thing is that the spool is 500 meters!

It is so lightweight that I am thinking about running two of these in parallel as guylines.

–B.G.–

[Larry De La Briandais]

The one thing I would worry about with something that small in diameter is abrasion. Two parallel lines will help as one can carry the load if the other breaks.

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