static rope for rappelling and ascending

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static rope for rappelling and ascending

Postby bobby49 » Oct 1, 2018 9:19 pm

We have already weeded out UHMWPE rope. That leaves us with nylon, polyester, and combinations thereof. Let's start with the assumption that all static vertical ropes get the necessary rope pads.

It seems like most vertical cavers try to use 10mm-12mm ropes whenever possible. If the rope has a tough "canyoneering" sheath, then that is a plus. Then on some occasions, a cave trip leader might decide to use a 9mm rope, but hardly anybody moves down very far into what we could call a single rope of a two-rope setup. Who uses 8mm? I'm guessing that nobody uses 8mm or thinner.

One guy said that he used 11mm or 12mm if he didn't have to use a very long length or if he did not have to carry that weight very far. He said that he was inclined to use 8mm-9mm rope when he did have a long carry-in.

As you might tell, I am shopping around for another new rope, probably around 200 feet. I regularly use a 3/8ths inch rope and prior to that was a tough 9mm rope.
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Re: static rope for rappelling and ascending

Postby GroundquestMSA » Oct 2, 2018 11:41 pm

11mm is considered standard and PMI Pit rope and its equivalents are the tough as nails products that are most popular. Highline makes an excellent and very cheap 11mm rope. Atwood makes a good cheap polyester 7/16".

I use 8mm often enough simply because I have a length. It is very nice to carry and work with and less nice to climb on. There is more bounce and there are more feeding issues when the rope is slimed. 8mm is harder to find, often more expensive, and less versatile, so I probably won't buy more.
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Re: static rope for rappelling and ascending

Postby trogman » Oct 3, 2018 3:55 pm

I have a friend who says he did Fantastic Pit with either 8 or 9 mm. As long as the rope is hanging free, and not subject to abrasion, it should be plenty strong enough to support the average caver. Not sure if I would use it to climb tandem.
The chief benefit of smaller rope is that it weighs a bit less. That doesn't matter much until you get up to really long lengths.

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Re: static rope for rappelling and ascending

Postby bobby49 » Oct 4, 2018 1:40 am

A fatter rope is likely to last longer in years, if that is a factor.
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Re: static rope for rappelling and ascending

Postby snoboy » Oct 6, 2018 5:01 pm

In my experience, 11 mm is generally too fat to move easily on once you get it dirtyy. This is of course related to the fact that I cave on a stop. 9.5 mm is my happy compromise, although I have done plenty of drops on 8 mm when I ran out of rope, or on expedition. Often related...
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Re: static rope for rappelling and ascending

Postby CaverCarl » Oct 21, 2018 6:09 pm

Where do I start?

RAPPELLING: the biggest variable is rappelling is the rope. I don't mean what the rope construction material is, I don't mean how tight the sheath is, I don't mean how thick the rope is. (I'm limiting this discussion to 1/2" aka 12.5mm to 7/16" aka 9mm). Even the same rope will vary. It may have gone caving the day before and be gritty. Even if it didn't cave before, the top may be dry and the bottom get's some water spray and it's wet. New rope is fast, Skinny rope is fast, Wet rope is fast, Old rope is slow, Dirty rope is really slow, Fat rope is slower, But how do you know where on each drop the rope is now dirty, wet, or dry? That's why racks are cool, you can vary your friction as you go.

Almost the entire caving community in the US is using Nylon sheath and Nylon core. It works and will continue for years to be the standard. However I do not use nylon, here's why. 1st it stretches more than Polyester. For every step you take when you climb the first part of that stroke removes stretch the next part move you up. 2nd Poloyester adsorbs less water. About 1/2 of my cave trips the water adsordbsion is not an issue. But almost all of the trips where it's water is not an issue, stamina is also not an issue. The extra weight of a wet rope only counts when your going deep, far, or long.

Diameter of rope is two different discussions, rope strength, and rope weight.
The standard for the US caving community is 7/16" (11mm). I don't buy 11mm, here's why.
I'm Fire Department. Bear with me here, National Fire Protection Agency !500 standard lists the minimum breaking strength for general purpose (2 person load rope) to be 9,000 lbs breaking strength. Although not official many people interperet this standard as being 300 lbs per FF (with turn out gear and SCBA) plus another FF being rescued and if you do the math that's a 15 to 1 safety factor over working load.
Cavers with gear and pack pretty much max out at 250 lbs.

DO YOU PLAN ON TANDEM CLIMBING THIS ROPE: (2 cavers on rope at the same time)
I don't consider tandem climbing anything less than 250' and it's rare that it's less than 400 when I do.
9mm poly or nylon will meet a 15 to 1 safety factor for a single caver so why do so many people buy a 250' or less rope that's fatter than 9mm?
If i was buying a rope less than 250' it would be no fatter than 10mm.

Several Rope manufacturers do not support or recommend a rope being older than 10 years. I do not know of anyone who "wore out" a rope. I know of many instances where a rope pad placement was not maintained, or completed due to miss-communication, or other circumstances that lead to the rope sheath being damaged and the rope was cut shorter to remove the bad spot. If you know anyone who claims that they wore out a rope I would greatly appreciate a brief discussion with that person.

Canyoneering is caving, except for: a big hike to get there, It's only rapells there's no climbing rope, there's no crawling, no mud, no stoop walks, great lighting (aka photos). So what's used for canyoneering rope is 9.5 Polyester because they don't want stretch when the do a pull down and they don't want water adsordbsion. The standard length is 200' (you usually bring 2-200' for the pull down).
I believe 10mm Polyester may be a liitle bit of overkill as far as strength goes but I'm ok with tandenming 10mm because if both caver's equal 450 lbs I've still got a 13.5 safety factor. (That's pretty dam close to the 15 to 1 that NFPA requires).

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