Wear out ascender rubber with change-overs?

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Re: Wear out ascender rubber with change-overs?

Postby Lava » Oct 8, 2010 4:02 am

NZcaver wrote:Easy fix. After attaching your SRTE Stop to your harness with the carabiner of your choice, take your short cowstail and clip it into the same attachment hole. Two carabiners, one hole. Problem solved.


Not exactly. Think about the process when passing a rebelay. There is a point where you will be unweighting and re-weighting the descender when you stand in the j-loop and unclip the short cowstail. In that moment when you sit back down you won't have the second carabiner in the hole, and that's exactly the time you need it there the most.
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Re: Wear out ascender rubber with change-overs?

Postby gdstorrick » Oct 8, 2010 4:26 am

Post deleted.
Last edited by gdstorrick on Jul 10, 2012 11:43 am, edited 1 time in total.
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Re: Wear out ascender rubber with change-overs?

Postby Stridergdm » Oct 8, 2010 9:25 am

NZcaver wrote:You know it's getting bad when you have to sneak out to check the mail so the wife doesn't see you with another package... :shhh:


But you can quit any time. Right?
Cavers rescue cavers!
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Re: Wear out ascender rubber with change-overs?

Postby NZcaver » Oct 8, 2010 10:28 am

Lava wrote:Not exactly. Think about the process when passing a rebelay. There is a point where you will be unweighting and re-weighting the descender when you stand in the j-loop and unclip the short cowstail. In that moment when you sit back down you won't have the second carabiner in the hole, and that's exactly the time you need it there the most.

A rebelay? Ah, so you're not talking about caving in the US then? :tonguecheek: Seriously, that's a good point and I was aware of it but forgot to mention the equally simple solution. Use another carabiner. Any one will do, locking or non. If you do the rappel test thing Scott's always talking about, you should not have any issues with a single carabiner through the gate of your SRTE. I never have.

gdstorrick wrote:
NZcaver wrote:Only 3?? I'm not one to boast, but... I'm up to 6 (not counting duplicates). :big grin::

Only 6?

Yes, as I've mentioned many times before... I'm not actually a collector, just an enthusiastic user who likes a little variety. I swear.

Stridergdm wrote:
NZcaver wrote:You know it's getting bad when you have to sneak out to check the mail so the wife doesn't see you with another package... :shhh:

But you can quit any time. Right?

Riiiiiiiiiight...
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Re: Wear out ascender rubber with change-overs?

Postby Lava » Oct 8, 2010 3:24 pm

NZcaver wrote:A rebelay? Ah, so you're not talking about caving in the US then? :tonguecheek: Seriously, that's a good point and I was aware of it but forgot to mention the equally simple solution. Use another carabiner. Any one will do, locking or non. If you do the rappel test thing Scott's always talking about, you should not have any issues with a single carabiner through the gate of your SRTE. I never have.


Heh, there are some places in the US where rebelays can be found. :shhh:

The second carabiner method is very safe, but it adds weight and an extra step to the process of crossing a rebelay. I'd like to keep my processes as simple as possible. And how do you expect me to impress European cavers with those few added extra seconds? :big grin:
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Re: Wear out ascender rubber with change-overs?

Postby fuzzy-hair-man » Oct 8, 2010 8:16 pm

Lava wrote:
NZcaver wrote:A rebelay? Ah, so you're not talking about caving in the US then? :tonguecheek: Seriously, that's a good point and I was aware of it but forgot to mention the equally simple solution. Use another carabiner. Any one will do, locking or non. If you do the rappel test thing Scott's always talking about, you should not have any issues with a single carabiner through the gate of your SRTE. I never have.


Heh, there are some places in the US where rebelays can be found. :shhh:

The second carabiner method is very safe, but it adds weight and an extra step to the process of crossing a rebelay. I'd like to keep my processes as simple as possible. And how do you expect me to impress European cavers with those few added extra seconds? :big grin:


I'm using a Petzl OK oval carabiner to attach my bobbin (Petzl Simple) now the oval carabiners seem much less prone to being able to trip the catch of the bobbin or stop. :kewl: and oval carabiners are the bomb when you need to strip your system to build hauls etc. From memory it is the width between the two sides of the carabiner that is important mailions and small carabiners mean it can pivot in the hole whilst the other side of the biner trips the catch, with the oval the other side of the biner is above the catch so there's nothing to trip. :woohoo:

Here's some pictures to hopefully illustrate, not saying an Oval can't trip the gate but I haven't been able to get it to do it.
Image
Image
See how the gate side of the oval contacts the catch pretty much on top of the catches hinge? this makes it unable (as far as my attempts have gone) to trip the catch, rotate the oval any which way and I can't seem to get it any closer to opening the catch than that.

With regard to the rappel check I think one of the things caving does well compared to a lot of other sports that use abseiling is that generally when you are on descent all your weight is on the abseil device, our system of checks and rigging (especially Alpine style) ensure that the descender is weighted and unlocked before removing safeties which to me ensures the user clearly knows which hand is controlling their descent before starting.
I've been doing a guiding course for abseiling and they use Prusik safeties above the rappel device and have reportedly experienced several slides while unlocking the descender (user grips the prusik and finds the prusik was at least partly holding them and not the descender), I contrast this to where I've helped instruct caving without these safeties (but we do use the rappel check although we don't call it that it's just part of getting on rope, rebelays, changeovers etc) and we've never had one, (both these cases have bottom belays in place BTW). Which similar to Gary's web post about makes me dubious about the value of Prusik safeties especially above the abseil device.
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Re: Wear out ascender rubber with change-overs?

Postby potholer » Oct 11, 2010 4:41 pm

Lava wrote:Results:
* Petzl Stop - opened easily by mallion and Superfly, could not be opened by Attache, OK, or Jake.
* Kong Indy - opened easily by mallion and Superfly, could not be opened by Attache, OK, or Jake.
* SRTE Stop - opened by ALL carabiners; very easily by the Superfly, Attache and OK, moderately difficult with the mallion, and extremely difficult with the Jake. I had to spin the Jake around to the narrower end and push it up onto the gate a little and then really torque it over to do so.

Were those tests done with the descender attached to a harness, manipulating the descender only, or by manipulating an isolated descender and attachment with a hand on each?

Though it's easy to demonstrate the Stop+10mm maillon opening by two-handed manipulation, I've tried in a more real life situation with the descender fastened to a harness, and if only manipulating the descender (in a way that simulates the most homicidal combination of rope movement and cave-wall-catching), I found it a whole different world.

Even adding a little freedom of movement to the maillon seriously changes the ease of 'accidental' opening, but also, with the maillon fixed to some degree relative to the body, even to get close to an opening action seems to require descender manouvres that seem pretty extreme, and rather less likely than when manipulating both descender and maillon.
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Re: Wear out ascender rubber with change-overs?

Postby Lava » Oct 12, 2010 11:17 pm

potholer wrote:Were those tests done with the descender attached to a harness, manipulating the descender only, or by manipulating an isolated descender and attachment with a hand on each?

Though it's easy to demonstrate the Stop+10mm maillon opening by two-handed manipulation, I've tried in a more real life situation with the descender fastened to a harness, and if only manipulating the descender (in a way that simulates the most homicidal combination of rope movement and cave-wall-catching), I found it a whole different world.

Even adding a little freedom of movement to the maillon seriously changes the ease of 'accidental' opening, but also, with the maillon fixed to some degree relative to the body, even to get close to an opening action seems to require descender manouvres that seem pretty extreme, and rather less likely than when manipulating both descender and maillon.


I did the tests holding the descender stationary and closed with my left hand, and manipulating the carabiner with my right. You're right, it is a lot less likely to happen in real life, but it's not impossible.
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