Improving rigging for descending?

Discuss vertical caving, equipment, & techniques. Also visit the NSS Vertical Section.

Moderator: Tim White

Re: Improving rigging for descending?

Postby Rangeoflight » Nov 4, 2014 10:41 pm

Out of curiosity I did a google search for Kingfisher ropes. Every result shows it as a marine rope. 10mm polyester braid on braid specs show a 2300kg MBS and designated as "low stretch". Pretty sure it wouldn't be my first choice for a caving rope other than as a handline. I highly recommend that you get with some local cavers to have an in depth discussion/demonstration on rigging, ropes, systems, etc.
Rangeoflight
Infrequent Poster
 
Posts: 10
Joined: Jan 14, 2013 3:50 pm
NSS #: 64028
  

Re: Improving rigging for descending?

Postby Stridergdm » Nov 5, 2014 12:19 pm

Yeah, reading this, I think you're sort of looking the problem wrong.

Modern ropes designed for SRT are fairly durable and if you are worried about wear and tear on the rope, pad the rope.

Here in the US, some folks refer to it as IRT (indestructable rope technique) because of our use of 11mm rope. Europe often uses thinner ropes that are a bit more prone to wear.

Even then, the tree ain't gonna be the problem, the edge is.

Also, I would highly suggest if you do end up using a tensionless hitch, don't put the figure 8 in the END of the rope if you extra rope. Leave as much of the extra rope at the top of the pit and put an 8 (or other knot) midway in. In a typical, correctly tied tensionless hitch, the knot will see virtually zero force.

But by leaving the extra rope at the top, if you need to build a haul system, or want to put say 10' over the edge to make another rope to ease the edge transition problem you've got it.

At the bottom of the drop, the only thing all that extra rope can do is give rocks a soft place to land on.
Cavers rescue cavers!
User avatar
Stridergdm
NSS Hall Of Fame Poster
 
Posts: 922
Joined: Nov 1, 2005 10:08 am
Location: Capital District NY and Northern Virginia
Name: Greg Moore
Primary Grotto Affiliation: RPI Grotto
  

Re: Improving rigging for descending?

Postby Tim White » Nov 5, 2014 12:43 pm

I just want to comment on a couple of things in Rangeoflight post and maybe add a bit more.

I too can only find Kingfisher being a marine rope. This is NOT rated for life safety.

Rangeoflight stated that 10mm shows a MBS of 2300kg. I cannot find a MBS rating, only something called Break Strengths. I’m not sure what this rating is.

MBS or minimum breaking strength of life safety rope is calculated using the 3 Sigma. This is verified by by a third party and independent testing. 5 test samples of rope pulled to destruction and an average (mean) is taken then 3 standard deviations are subtracted to give the MBS. Results is that any given rope should actually be stronger than the manufactures published MBS.

Hope this is clear as mud. :big grin:
Be safe,
Tim White 26949 RL FE

Southeastern Region Coordinator - NCRC
Editor, Nylon Highway
Senior Technical Manager - Over the Edge, Inc.
User avatar
Tim White
Global Moderator
 
Posts: 843
Joined: Sep 8, 2005 11:57 am
Location: Suwanee, GA
  

Re: Improving rigging for descending?

Postby alfred » Nov 6, 2014 6:44 am

Thanks for your replies.

You're right that Kingfisher is a marine rope, not purposely built for rappeling or caving, however since its material (polyester), diameter (10mm) and minimum breaking load (2300 kg) are right, what difference would it made unless the manufacturer is overly cheating?

Also, to have a minimum breaking load, it takes at least some tests to yield a result which you can then call, based on the numbers you have in hand, a "minimum".

Considering 10x bodyweight MBL is used recreationally by some but the Fire brigade suggests 15x bodyweight, by being at 30x bodyweight is should be safe enough not to require an additional certification which as far as I know could be just a reason to slap a higher price tag on a rope.

Industrially, even if you aren't lifting live loads, it's not like you can accept like if it was nothing that a rope breaks (and the load crushes everything in its way) or you make a month's worth of work vanish due to poor materials. Surely, a lower loss than somebody's life, but putting things in that point of view seems like everybody in hauling and industrial duties is reckless and can afford to break a rope per month while working.

This is just my humble opinion though and I'm more than willing to read yours.

Thanks again :)
alfred
Infrequent Poster
 
Posts: 7
Joined: Nov 2, 2014 5:17 pm
  

Re: Improving rigging for descending?

Postby graveleye » Nov 6, 2014 9:46 am

Tim, what kind of rope would you guys use on a rescue or an extraction?
ad astra per aspera

http://www.myspace.com/jamthecontrols

The views expressed in this post are not necessarily those of any organization I am affiliated with.

Become a sustaining member of the SCCI
User avatar
graveleye
Global Moderator
 
Posts: 2934
Joined: Mar 14, 2006 11:12 am
Location: Georgia, USA
Name: Kevin Glenn
NSS #: 57238RL
  

Re: Improving rigging for descending?

Postby GroundquestMSA » Nov 6, 2014 4:46 pm

alfred wrote:You're right that Kingfisher is a marine rope, not purposely built for rappeling or caving, however since its material (polyester), diameter (10mm) and minimum breaking load (2300 kg) are right, what difference would it made unless the manufacturer is overly cheating?


I agree. I wholeheartedly embrace the idea that our decisions should be based on what works, and is safe, not what is mainstream (or certified). That said, many things are widely preferred for good reason. Depending on how you rig your rope, abrasion resistance may be important. Lots of arborists use braid-on-braid, but many of them also climb (and descend) with knots instead of toothed ascenders. I don't know if that matters but it's probably worth investigating. Also the hand of the rope may effect the way it works with your vertical gear. Test everything, keep educating yourself, use your brain, be careful, have fun, and make your own good choices.
User avatar
GroundquestMSA
NSS Hall Of Fame Poster
 
Posts: 1343
Joined: May 5, 2011 1:32 pm
  

Re: Improving rigging for descending?

Postby NZcaver » Nov 6, 2014 7:03 pm

alfred wrote:You're right that Kingfisher is a marine rope, not purposely built for rappeling or caving, however since its material (polyester), diameter (10mm) and minimum breaking load (2300 kg) are right, what difference would it made unless the manufacturer is overly cheating?

Also, to have a minimum breaking load, it takes at least some tests to yield a result which you can then call, based on the numbers you have in hand, a "minimum".

Considering 10x bodyweight MBL is used recreationally by some but the Fire brigade suggests 15x bodyweight, by being at 30x bodyweight is should be safe enough not to require an additional certification which as far as I know could be just a reason to slap a higher price tag on a rope.

Industrially, even if you aren't lifting live loads, it's not like you can accept like if it was nothing that a rope breaks (and the load crushes everything in its way) or you make a month's worth of work vanish due to poor materials. Surely, a lower loss than somebody's life, but putting things in that point of view seems like everybody in hauling and industrial duties is reckless and can afford to break a rope per month while working.

As a teenager, I rappelled on boat rope many times. Really old stuff, too. I survived just long enough to connect with cavers and learn safer and more efficient ways of doing things. This was also WAY before the internet. Making personal choices and bearing the responsibility for those choices is a wonderful thing. Also, in my case, ignorance was bliss while it lasted.

An MBS of 2300 kg for a 10mm rope is reasonable. Of course once you tie a knot in that rope (other than a tensionless hitch), you could lose 20-50% of the rated MBS of the rope depending on the type of rope and knot. You might also consider the construction of the rope and possible failure modes. Marine ropes have different handling properties, are often less abrasion resistant, and behave differently when knotted, shock loaded, descended on, ascended on, covered in mud and grit, etc. Marine ropes and the fibers used to construct them are generally not tested or quality-controlled as stringently as ropes made for life safety use.

Will that rope work for you without failing? Probably. Are their better options? Yes.

Good luck.
User avatar
NZcaver
Global Moderator
 
Posts: 6316
Joined: Sep 7, 2005 2:05 am
Location: Anchorage, Alaska
Name: Jansen
NSS #: 50665RL
Primary Grotto Affiliation: CCG
  

Re: Improving rigging for descending?

Postby Stridergdm » Nov 6, 2014 8:06 pm

Honestly, the MBS of a rope isn't necessarily the most important factor.

I've seen that mentioned several times in threads here on On Rope. And yes, you want a MBS that's "adequate" but 10x, 15x,30x... really stops mattering at some point.

What's the MBS of your anchor? If it's only 2x and you put 2.1x load on the rope, you now have your 30x rope laying at the bottom of the pit.

You have to look at the total system, and not just the system safety ratio, but how things will handle the environment.

For example, I just put some dyneema in my frog system for my leg loop and am LOVING it (zero stretch!)

If I did my math right, it's got 47x my weight in MBS. But I wouldn't use it for rigging. It's just not the appropriate choice.

I think that's the point folks are making with the rope you'r using. It's not nearly as bad choice perhaps as using dyneema as your mainline, but it's not necessarily the best choice.

Something like PMI Pit rope is designed to be strong AND tough and very resistant to wear. (that said there's other many other good ropes out there that people prefer.)

Oh and as for rescue, I'd say various PMI or other similar ropes. 11mm.
Cavers rescue cavers!
User avatar
Stridergdm
NSS Hall Of Fame Poster
 
Posts: 922
Joined: Nov 1, 2005 10:08 am
Location: Capital District NY and Northern Virginia
Name: Greg Moore
Primary Grotto Affiliation: RPI Grotto
  

Re: Improving rigging for descending?

Postby trogman » Nov 8, 2014 7:41 am

One thing that I found helpful when rigging to a tree: always rig as high as possible. This will generally give you better clearance from the lip of the pit. This puts less stress on the rope, and also makes climbing out over the lip easier. This usually works better if there is a branch or knot in the tree just below your rig point, to keep the rope from slipping down the trunk.

Trogman :helmet:
User avatar
trogman
NSS Hall Of Fame Poster
 
Posts: 911
Joined: May 2, 2008 8:35 am
Location: North Alabama
Name: Stephen Brewer
Primary Grotto Affiliation: Gadsden Grotto
  

Re: Improving rigging for descending?

Postby Stridergdm » Nov 9, 2014 7:36 am

trogman wrote:One thing that I found helpful when rigging to a tree: always rig as high as possible. This will generally give you better clearance from the lip of the pit. This puts less stress on the rope, and also makes climbing out over the lip easier. This usually works better if there is a branch or knot in the tree just below your rig point, to keep the rope from slipping down the trunk.

Trogman :helmet:


I would quibble with this a bit and say "as high as is safely possible". Keep in mind the higher you rig in the tree, the more torque you put into the system and I've been in a few places with trees with shallow enough root systems I'd be very leery of the torque.

Other than that, yeah, I'd agree, do what you can to solve the edge problem.
Cavers rescue cavers!
User avatar
Stridergdm
NSS Hall Of Fame Poster
 
Posts: 922
Joined: Nov 1, 2005 10:08 am
Location: Capital District NY and Northern Virginia
Name: Greg Moore
Primary Grotto Affiliation: RPI Grotto
  

Re: Improving rigging for descending?

Postby alfred » Nov 18, 2014 8:10 am

Thank you all for your answers.

I think that ropes meant for life saving should and probably are tested by stricter criteria, however I should try an indipendant lab testing to really clear this in my mind rather than wanting to believe in this.

I agree to the anchor importance, after all a chain is only as strong as its weakest link, hence I use >22 kN screwlock carabiners.

Thank you
alfred
Infrequent Poster
 
Posts: 7
Joined: Nov 2, 2014 5:17 pm
  

Re: Improving rigging for descending?

Postby Vertigo » Nov 30, 2014 10:01 pm

There are many ways to rig. Too much time can be spent rigging and re-rigging a drop. Use whatever works safely and quickly. Also consider your caving buddies. You want them to be comfortable with the rig and able to determine that it is safe. Rigging for a potential rescue is not a bad idea if it doesn't involve extra time or equipment.
User avatar
Vertigo
NSS Hall Of Fame Poster
 
Posts: 500
Joined: Sep 28, 2006 8:06 pm
Location: Chattanooga, TN
  

Previous

Return to On Rope!

Who is online

Users browsing this forum: Yahoo [Bot]

cron