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Nylon or Polyester?

Discussion in 'Archives - Yahoo Canyons Group' started by douglas@infowest.com, Sep 25, 2000.

  1. I'm looking at a brochure from Sterling. They make two different kinds of static rope, one is the Superstatic/Nylon Static Rope and the other is a HTP/High Tenacity Polyester Static Rope.

    The poly stats show for a 3/8 rope 7330 lb Tensile Strength as compared to 6500 for the nylon.

    The poly shows 0.9% Elongation under 300 lb load while the nylon shows 3.5%

    The poly weight is 5.1 lb for 100 feet as compared to 4.7 for the nylon.

    It appears the polyester rope is by far the better rope for canyoneering, the brochure claims it is more durable, les prone to cutting and abrasion. Both ropes have DryCore, it claims to keep the ropes dry.

    So, under real world tests and use, what is the preference out there. Nylon or Poly? Why?

    Doug
  2. Tom Jones

    Tom Jones Guest

    hmoon@petzl.com wrote:

    ...
    > So, under real world tests and use, what is the preference out >> there. Nylon or Poly? Why?
    If you never have a rescue or plummet and always have solid anchors, poly > might be an option. Just be aware its energy absorption is next to nil > (higher loads on anchors and people) and this can be a liability in > certain situations.
    hank

    Hank's point is well taken. Even a static nylon rope has considerably more elasticity than polyester. With a non-elastic rope, even small slips can generate pretty substantial loads. The problem is not the rope breaking, the problem is placing high loads on the anchors. I hope we are all aware that the canyoneering anchors we are using (trees, bushes, jammed chockstones, "museum quality" bolts) are not very stout.

    Tom
  3. <font size="2" face="Courier New">The poly stats show for a 3/8 rope 7330 lb Tensile Strength as <br\>compared to 6500 for the nylon. </font> <br\><font size="2" color="#800080" face="sans-serif">Strength is not really an issue with this type and diameter of rope. What do you really need for canyoning (rescue possible)? 2XBodyweight with an acceptable safety factor. Assuming (wet and with pack) bodyweight of about 1 kN, you would need a MBS of about 10 kN to achieve a standard "industrial" safety factor of 5:1 (this assumes the rope is unknotted - you would need 20 kN to acheive this same factor when knotted). So why do most folks buy larger diameter ropes? Mostly for durability and/or anti-cut insurance. On strength alone, you could get by with 7 mm cord.</font><font size="2" face="Courier New"> <br\> <br\>The poly shows 0.9% Elongation under 300 lb load while the nylon <br\>shows 3.5%</font> <br\><font size="2" color="#800080" face="sans-serif">No real benefit for canyoning.</font><font size="2" face="Courier New"> <br\> <br\>The poly weight is 5.1 lb for 100 feet as compared to 4.7 for the <br\>nylon.</font> <br\><font size="2" color="#800080" face="sans-serif">This can be deceptive. In general, wet nylon rope will be heavier than wet poly of same diameter as poly absorbs very little water compared to nylon. This makes so-called "DryCore" redundant.</font><font size="2" face="Courier New"> <br\> <br\>It appears the polyester rope is by far the better rope for <br\>canyoneering, the brochure claims it is more durable, les prone to <br\>cutting and abrasion. &nbsp;Both ropes have DryCore, it claims to keep the <br\>ropes dry.</font> <br\><font size="2" face="Courier New"> <br\>So, under real world tests and use, what is the preference out <br\>there. &nbsp;Nylon or Poly? &nbsp;Why?</font> <br\><font size="2" color="#800080" face="sans-serif">If you never have a rescue or plummet and always have solid anchors, poly might be an option. Just be aware its energy absorption is next to nil (higher loads on anchors and people) and this can be a liability in certain situations.</font> <br\><font size="2" color="#800080" face="sans-serif">hank</font>
  4. The caving book "On Rope" has a chapter on historical rope use and a good comparison between Polyester, Nylon, Spectra, Polypropalene, Aramid, and others. I don't remember why but when looking at the chart Nylon was the winner. In addition to the mentioned specifications melting temperature and UV resistance where specified.

    -----Original Message----- From: hmoon@petzl.com [SMTP:hmoon@petzl.com] Sent: Tuesday, September 26, 2000 11:00 AM To: canyons@egroups.com Subject: Re: [canyons] Nylon or Polyester?

    The poly stats show for a 3/8 rope 7330 lb Tensile Strength as compared to 6500 for the nylon.

    Strength is not really an issue with this type and diameter of rope. What do you really need for canyoning (rescue possible)? 2XBodyweight with an acceptable safety factor. Assuming (wet and with pack) bodyweight of about 1 kN, you would need a MBS of about 10 kN to achieve a standard "industrial" safety factor of 5:1 (this assumes the rope is unknotted - you would need 20 kN to acheive this same factor when knotted). So why do most folks buy larger diameter ropes? Mostly for durability and/or anti-cut insurance. On strength alone, you could get by with 7 mm cord.

    The poly shows 0.9% Elongation under 300 lb load while the nylon shows 3.5%

    No real benefit for canyoning.

    The poly weight is 5.1 lb for 100 feet as compared to 4.7 for the nylon.

    This can be deceptive. In general, wet nylon rope will be heavier than wet poly of same diameter as poly absorbs very little water compared to nylon. This makes so-called "DryCore" redundant.

    It appears the polyester rope is by far the better rope for canyoneering, the brochure claims it is more durable, les prone to cutting and abrasion. Both ropes have DryCore, it claims to keep the ropes dry.

    So, under real world tests and use, what is the preference out there. Nylon or Poly? Why?

    If you never have a rescue or plummet and always have solid anchors, poly might be an option. Just be aware its energy absorption is next to nil (higher loads on anchors and people) and this can be a liability in certain situations.

    hank Sponsored by the American Canyoneering Association http://www.canyoneering.net <http://www.canyoneering.net>

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