Goto Chockstone Home

  Guide
  Gallery
  Tech Tips
  Articles
  Reviews
  Dictionary
  Links
  Forum
  Search
  About

      Sponsored By
      ROCK
   HARDWARE

  Shop
FREIGHT FREE
in Australia

Black Diamond: SET of 8 "C4" Cams and 8 matching wire gates. Sizes .3 .4 .5 .75 1 2 3 & 4 and 8 anodised "neutrino" - wire gate karabiners.   $625.00
20% Off

Chockstone Photography Australian Landscape Photography by Michael Boniwell
Australian Landscape Prints





Chockstone Forum - For Sale

Buy and Sell Used Climbing Gear Please do not post retail SPAM.

Author
Top rope gear...
alpinedan
29/09/2007
3:44:40 PM
25m of 11mm static rope, and 2 x Dmm steel carabiners (45kn), rarely used and in top condition as I quickly preferred the sport leading at Kangaroo Point over TR. (I only bought the gear for KP top-roping). Moving to NZ next month and cant be arsed paying the excess baggage fee for it... going cheap at $50 for the lot. I am in Brisbane but will ship it... shipping not included in price.

skink
29/09/2007
4:54:54 PM
Erm, not sure that top roping on static rope is such a great idea. Even with an attentive belayer, slack can creep in, and falling on a static with slack in the system is bad with a capital BAD.
Tris
29/09/2007
5:02:19 PM
Top roping on static is fine (provided you are using a nylon static rope). You would be surprised how much a static rope stretch.

If you have heaps of slack in the system then it could start to get hairy, but if thats the case you need to look at the skill of your belayer.

All that aside, with the length that Dan is advertising I imagine that it's just an anchor rope, not a top rope.

Tris
alpinedan
29/09/2007
5:56:37 PM
Sorry I should have been more specific... Tris is correct, the static rope is only for top rope anchors... or for that matter any anchors... you could chop it up and use it for permanent anchors on some alpine route you plan to guide clients up... :D

muki
29/09/2007
8:16:21 PM
Top ropeing on static rope is fine, most gyms use a blended rope called gym line, cos it has static
propertys that prolong use, if they used normal dynamic ropes they would wear out too quickly to be cost
eficient!
As long as the belayer is not tethered to the ground, the counter balanced weight of a belayer more than
covers the dynamic quality needed to eliminate a static shock loading, even with a little slack.
These destructive (deadly) shock loadings are more common when on a (static) sling at an anchor, then
slipping, and falling onto the sling, this can kill you, even on a short fall, 1/2m sling, down bellow you on
the anchor, then the fall = 1m static shock load = internal injurys, & or brocken spine.
Samuel
16/10/2007
8:28:43 PM
I am interested if you still have the gear ?

anthonyk
16/10/2007
11:33:43 PM
static ropes aren't completely static, they're just less stretchy. but since you've got 1-2x the length of the climb in rope out all the time you'll get plenty of bounce. its probably got more stretch distance than a "dynamic" lead rope at the first or second (or third or even higher) bolt.

anthonyk
17/10/2007
11:25:03 AM
On 16/10/2007 anthonyk wrote:
>static ropes aren't completely static, they're just less stretchy. but
>since you've got 1-2x the length of the climb in rope out all the time
>you'll get plenty of bounce. its probably got more stretch distance than
>a "dynamic" lead rope at the first or second (or third or even higher)
>bolt.

fyi static ropes stretch between about 1-2% and dynamic ropes between about 5%-8% (8% is a maximum standard i think). so you get about 2.5x-8x more stretch distance (which determines the impact) for the same length of rope. on a 20m climb you're getting between 60cm and 30cm stretch on a static rope with 1.5% stretch (assuming anchor is minimal resistance). with a lead rope of 6% you'll get 24cm with 4m out, up to (theoretically) 1.2m with 20m out, although in reality the resistance of it going through all the quickdraws will reduce the effective amount of rope stretching significantly. if we say it halves the amount of rope stretching when you're at the top of the climb then you're getting about 60cm stretch.

in that example the static is giving btw 30-60cm stretch (maybe 20-50cm with some anchor friction) and the dynamic on lead giving btw 24-60cm (assuming friction takes half of it out of play at the top), basically the same. so there shouldn't be any issues if someone took more of a fall on the static either, not just weighting it, since its giving about the same amount of stretch that a dynamic would.

Eduardo Slabofvic
17/10/2007
11:58:16 AM
There is now 0 stretch rope available, however the price that was quoted me was astronomical. I
understand that it is currently only used in the movie industry (where budgets are correspondingly
astronomical) instead of wire rope, as there is little risk to bystanders if the rope breaks, unlike wire rope
which has the tendency to turn bystanders into easy to carry chunks.

- "twang!!"....oops, looks like another trip to the pig farm.
Tris
17/10/2007
12:39:56 PM
Anthony, I don't think you are correct with your figures on rope stretch.

A dynamic rope will usually stretch about 9-10% under a static load (the maximum in the standard is 10% from memory). But under a dynamic load the rope will stretch between 30 and 40% (40% is the maximum under the standard).

I don't think that a top roping fall would be completely static (please correct me if I am wrong), but it would not be as much as a dynamic load (they get this figure from the first factor 2 fall test they do). So I imagine the amount of stretch would be somewhere in between.


Tris

anthonyk
17/10/2007
1:22:30 PM
On 17/10/2007 Tris wrote:
>Anthony, I don't think you are correct with your figures on rope stretch.
>
>A dynamic rope will usually stretch about 9-10% under a static load (the
>maximum in the standard is 10% from memory). But under a dynamic load the
>rope will stretch between 30 and 40% (40% is the maximum under the standard).

here's stats of stretch of blue water ropes under static load (80kg) http://www.spelean.com.au/BW/TM/BWtechdyn.html:



and according to this page http://www.spelean.com.au/BW/specs.html :

"The maximum static load stretch allowed by the UIAA is 8% for single ropes and 10% for half ropes"

this page http://www.spelean.com.au/BW/BWstatic.html shows the specs of a blue water II static to be 1.3%: "The kernmantle construction used in these ropes features a double-twist cable core for minimal low load stretch (1.3% under an 80kg load)"


maybe we're talking about different things, i'm just referring to stretch under static load. when you take more of a fall there's more stretch, but i'm sure the static load stretch is a fair guide about the relative stretch you'll get under a dynamic load. having said that i wouldn't recommend anyone try taking lead falls on a static rope even if there is a fair amount of it out to find out..

anthonyk
17/10/2007
1:28:15 PM
On 17/10/2007 Eduardo Slabofvic wrote:
>There is now 0 stretch rope available, however the price that was quoted
>me was astronomical.

even then it wouldn't be "zero" stretch, it'd be "near-zero". if you have zero stretch you get an infinite force (is this right?).
Tris
17/10/2007
3:44:09 PM
Interesting.

I was getting my information from here:

http://www.bealplanet.com/portail-2006/index.php?page=caracteristiques&lang=us

Which has the following bit of information:

Measured under a load of 80kg it must not exceed 10% for single rope, 12% for double rope, and 10% for two strands of twin rope together..

Now this could just be what beal adhear to. I will have to do some more research.

Tris

Eduardo Slabofvic
17/10/2007
3:51:12 PM
On 17/10/2007 anthonyk wrote:
>even then it wouldn't be "zero" stretch, it'd be "near-zero". if you
>have zero stretch you get an infinite force (is this right?).

I dunno about "infinite force". I offered this tit bit of info by way of an interesting sideline. I think it has no
application to climbing. As I understand it, it's purpose is as an alternative to wire ropes.
Tris
17/10/2007
3:52:13 PM
Ok, I just had a look at the UIAA websight, and the test that they use, found here under #101, dynamic ropes (look at the pictorial link, not the text link):

http://www.uiaa.ch/?c=310

States that the static elongation for a single rope should not exceed 10% (12% for double ropes).

Mabye the blue water page is out of date?

Tris
dougo
17/10/2007
5:45:44 PM

>On 17/10/2007 anthonyk wrote:
>even then it wouldn't be "zero" stretch, it'd be "near-zero". if you
>have zero stretch you get an infinite force (is this right?).

technically it is impossible to have a zero stretch rope.

If you want the maths, consider that you have some initial falling velocity, Vi, and you stop over some distance, d, giving you a final velocity of Vf = 0.

From good ol HSC physics, (Vf )^2 = (Vi)^2 - 2xaccelerationx distance
i.e. acceleration = [(Vf )^2 +(Vi)^2]/2d
if you sub a stopping distance of 0 for a rope with no stretch, you get an infinite deceleration. F = ma then translates to an infinite force and a broken back.

The ropes in question would have to be a "near zero" stretch ropes
alpinedan
18/10/2007
6:12:18 PM
SOLD

There are 17 messages in this topic.

 

Home | Guide | Gallery | Tech Tips | Articles | Reviews | Dictionary | Forum | Links | About | Search
Chockstone Photography | Landscape Photography Australia | Australian Landscape Photography

Please read the full disclaimer before using any information contained on these pages.



Australian Panoramic | Australian Coast | Australian Mountains | Australian Countryside | Australian Waterfalls | Australian Lakes | Australian Cities | Australian Macro | Australian Wildlife
Landscape Photo | Landscape Photography | Landscape Photography Australia | Fine Art Photography | Wilderness Photography | Nature Photo | Australian Landscape Photo | Stock Photography Australia | Landscape Photos | Panoramic Photos | Panoramic Photography Australia | Australian Landscape Photography | Mothers Day Gifts | Gifts for Mothers Day | Mothers Day Gift Ideas | Ideas for Mothers Day | Wedding Gift Ideas | Christmas Gift Ideas | Fathers Day Gifts | Gifts for Fathers Day | Fathers Day Gift Ideas | Ideas for Fathers Day | Landscape Prints | Landscape Poster | Limited Edition Prints | Panoramic Photo | Buy Posters | Poster Prints