Knots Weaken Rope

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Drifter
Posts: 522
Joined: Fri Jan 12, 2007 9:54 am

Knots Weaken Rope

Postby Drifter » Tue Jun 05, 2007 7:13 am

http://www.caves.org/section/vertical/n ... trope.html
\"Knots Weaken Rope
They do! A great deal is written about which knots weaken a rope most. An angle, a kink, or a knot, stresses the fibers unevenly and weakens the rope. If this concerns you, you are using rope that's too thin. Although some knots in some ropes are claimed to only weaken a rope to about 80% of its rated strength, other knots weaken a rope to about 50%. It is therefore simpler, and certainly safer, to assume that even brand new rope will perform at no more than 50% of its rated breaking strength. And, if the rope is old, worn, or damaged by sunlight or chemicals - expect considerably less. For some useful test results visit Dave Richards' Knot Break Strength vs Rope Break Strength on the National Speleological Society Website.\"

Drifter
Posts: 522
Joined: Fri Jan 12, 2007 9:54 am

Postby Drifter » Tue Jun 05, 2007 8:55 am

I have been told that a double line fisherman is a 80 per cent knot. When you tie a double line fisherman in a rope it weakens the rope by 20 per cent and the rope is working at 80 per cent of its maximum strength.

douard
Posts: 39
Joined: Mon Mar 27, 2006 5:48 pm

Postby douard » Tue Jun 05, 2007 10:18 am

so what? i mean so the rope now has a 1800 vs 2200 kg breaking strain. big whoop! when has there ever been a documented case of a rope snapping when it wasn't due to being cut or damaged by something else (sharp edge, chemicals). how are you going to generate such a fall when climbing? i's be more worried about my gear than the knot if was taking a 50m wipper

Grigri
Posts: 293
Joined: Wed Jun 08, 2005 8:49 pm

Postby Grigri » Tue Jun 05, 2007 11:03 am

Hey Drifter: May your nerve fail and your rope snap!

mkboy
Posts: 106
Joined: Fri Oct 06, 2006 8:48 am
Location: PTA

Postby mkboy » Tue Jun 05, 2007 12:51 pm

Drifter is stressing because he hs a habit of buying sub-standard or industrial static ropes as opposed to good dynamic stuff :wink:

Drifter,

How about you take your rope,tie it to Bloukraanz bridge, tie a fishermans knot in the middle and jump off? all in the name of science mate! :lol:

let us know how it went, ok?

Skapie
Posts: 21
Joined: Tue Jun 05, 2007 3:09 pm
Location: Krugersdorp

Postby Skapie » Tue Jun 05, 2007 3:16 pm

Ropes don't break under normal conditions, regardless of the knot you use.
But I believe any climber must continiously try to learn more and improve his knowledge and skill.
Keep it simple and neat.

Grigri
Posts: 293
Joined: Wed Jun 08, 2005 8:49 pm

Postby Grigri » Tue Jun 05, 2007 10:51 pm

Agreed Skapie, educate yourself to avoid death/injury, but please, pleeeeeeeeez dont then regurgitate what you have just learnt on the web!! Drifter it's great you're learning, but most of learnt all of this years ago and reeeaaally dont need instruction from you of all people.

Drifter
Posts: 522
Joined: Fri Jan 12, 2007 9:54 am

Postby Drifter » Wed Jun 06, 2007 6:29 am

Grigri there are beginners and experience climbers on here who might appreciate the information. I have learned stuff here on climb.co.za by people posting information they got off off the internet. No one knows everything, someone might post something on here and another person might learn something knew. I don't see what is wrong about posting information about climbing which you found on the inernet on here if you think someone else might learn something knew from it. The internet is a learning tool as well.

Grigri
Posts: 293
Joined: Wed Jun 08, 2005 8:49 pm

Postby Grigri » Wed Jun 06, 2007 11:51 am

You would be way better off getting a good 'How to Climb' book by a respected and qualified author and taking some climbing courses from a properly qualified intstructor.

The information you get off the net is often incomplete, written by people who are not qualified, misleading or just plain incorrect. Learning to climb by browsing the net is a great way to get yourself killed! (as a result of having an incomplete and inadequate knowledge base). Leave the posting of 'how to' information, to people who are experienced enough to be qualified to comment, when people actually request such information.

The net can be very useful for rounding out your knowledge by tracking down pieces of specific information that may otherwise be difficult to obtain, but it should never be seen as all there is. Hence my irritation with these 'how to' posts/threads. The basics are very well covered by the books available, and an instructor will be able to give an intimate insight that no other source will provide. Perhaps refer to 'expert' sites (eg the manufacturer of your rope) for specifics (the strength of your rope etc.), but please dont rely on the net to keep you safe in the hills!!!

Anyways my rant for the day, I'll get off ur back now Drifter.

Drifter
Posts: 522
Joined: Fri Jan 12, 2007 9:54 am

Re:

Postby Drifter » Wed Jun 06, 2007 12:48 pm

Grigri wrote:You would be way better off getting a good 'How to Climb' book by a respected and qualified author and taking some climbing courses from a properly qualified intstructor.


Grigri I agree with what you said above however I do feel that the internet can give you some additional useful information about climbing.

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