Rope Question... or maybe concern

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Rope Question... or maybe concern

Postby fireman1904 » Jan 4, 2008 4:55 pm

I recently got a rope from a local fire department that was not going to be used. It is a 1/2 inch CMC rescue rope. Its about 75 feet long. Now here is my question.

It is brand new. I just used it the other day for the first time. On a short drop maybe 40 feet. By the time i got to the bottom the sheath of the rope had slid down the core enough that it was causing the rope to kind of catch in my rack. Kind of like it had bumps in it. You could see that it was bunching up like it needed to be streached out. It may not really be a problem since the rope was new and had never been streached at all. On the other hand when i climbed back up I had no problems with it at all in fact I was quite impressed at the fact that it didnt bounce hardly at all like some ropes do. I have a bluewater rope I have used a few times that was given to me by a friend (it was also brand new when I got it). Other than being a little bouncy on climbing I have had no problems with it. And I have never noticed the sheath slipping on it. I am probably just worrying but i just wondered what any of you guys thought. I dont have a ton of vertical experience so this was something I have just never noticed before.

mike
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Re: Rope Question... or maybe concern

Postby BrianC » Jan 4, 2008 5:49 pm

While on rappel it could be a serious problem! Check to verify where it came from and call the vender to see their response! As you said, it might need to be stretched, but the vender will know the product and it's properties!
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Re: Rope Question... or maybe concern

Postby wyandottecaver » Jan 4, 2008 6:03 pm

Mike,

good to see you on here! There are those much better qualified than I who can comment, but here is my experiance. I have several CMC ropes and they are great. Having the sheath slip or feel lumpy on rappel is a bad thing. One thing to check, is the very end of the rope taped, melted or sealed together? this helps hold the sheath in place and prevent it slipping. Another thing might be the fact that you are using 1/2" rope. CMC "rescue line" is a thicker and rougher rope than many, and if your using a micro rack or have the bars closely spaced it could be you just have more rope than your rack wants! many smaller racks will take 1/2" rope but they don't like it much. Hard to say without seeing the rope or your setup though.

Also be aware that some ascenders will not like 1/2 rope either, especially dirty or muddy 1/2 inch. The extra bulk and weight can help make a climb nicer though.

It would also be useful to get a history of the rope, did it come out of the bag new or was it laying in a storage room somewhere where one of you nefarious firemen used it to pull a firetruck? :)
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Re: Rope Question... or maybe concern

Postby NZcaver » Jan 4, 2008 6:44 pm

This can happen with some ropes. Try this. Chop the last inch off the bottom of the rope, and don't melt the end. "Milk" the mantle (sheath) over the kern (core) so there's more sheath than core hanging out at the end. Then chop the excess sheath back even with the core, and melt the end. Viola!

And if it does it again next time you rappel, repeat the process.

[Edit] Oh, I forgot.:doh: Wash and dry the rope first, like Ian suggested in his post.
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Re: Rope Question... or maybe concern

Postby ian mckenzie » Jan 4, 2008 6:49 pm

Many rope sheaths slip when new. Most cavers wash their new ropes and allow them to dry thoroughly before they use them, to help prevent this.

Note that 'unused' is not the same as 'new'. An unused rope still ages, but I don't think its strength reduction is much to worry about, as most of us cave on older, used ropes that have reduced strength from both age and usage.
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Re: Rope Question... or maybe concern

Postby fireman1904 » Jan 4, 2008 11:34 pm

Todd The rope is pretty new maybe two or three years old but has never been out of the bag except the few times I have had it out. It wasnt even on one of our trucks it was in a nice cool dry dark storage room but wasnt even in there long. When I noticed we had it I asked about it and they said I could have it. It still had the info on the bag from CMC. I looked it up online to see exactly what it was. It is 1/2 inch and is CMC Rescue Lifeline. My ascenders work really well on it and like I said I really liked climbing on it. It didnt bounce at all.

NZ I kind of thought about that... It is melted on the ends now and I had thought about cutting one end off and working the sheath down it some... maybe even cut it right before the next time I use it and letting it slide down then after it sits a little bit remelt the end or tape it again.

Unless someone thinks there is something actualy wrong with the rope I am going to try it again..

Oh and Todd are you gonna be on the trip sunday?? hope to see ya there.

Mike
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Re: Rope Question... or maybe concern

Postby fireman1904 » Jan 4, 2008 11:37 pm

OH todd another thing... I will bring the rope sunday too if you are there... As far as my setup.. I just have a regular rack with aluminum bars right now.. its not a micro rack or anything..
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Re: Rope Question... or maybe concern

Postby wyandottecaver » Jan 5, 2008 8:09 am

Odd,

I have 3-4 CMC lifeline ropes and none ever had to be trimmed. *shrug* I won't be there for the ridgewalk, at least not early but may catch up with you guys later.
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Re: Rope Question... or maybe concern

Postby Scott McCrea » Jan 5, 2008 12:02 pm

Has the rope been wet yet?

If not, try this... First measure the rope as accurately as you can, down to the inch. Soak it in water for a couple hours then let it air dry. Measure it again. It should shrink about 5-10%. There is a thread about this here.

Nylon shrinks when it gets wet. The core will shrink longitudinally (lengthwise). The sheath will shrink it's diameter, thus tightening the sheath around the core. No guarantee it will fix your problem, but it won't hurt.

Be sure to post your shrinkage results in the other thread. I don't think we have any data for CMC rope, so far. Thanks!
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