Wet or Dry rope SRTing ???

[TheBitterEnd]

I hated thermodynamics, and now you lot are dragging me into thinking about it in my spare time.  What a strange past time caving is.

I rather liked thermodynamics, in particular I liked the whooshing sound the concepts made as they flew over my head 

 

[Bob Mehew]

Has glazed rope ever been tested?

many times and it SEEMS seems to have no influence (I am not going to be categorical).  It is worth recalling that the main strength of a kernmantle rope is in the core, not the sheath.  Also if you look at the construction of kenrmantle, you will see that there is roughly 40% longer length of yarn in the sheath per unit length of rope because of their helical turning compared to the yarns in the core.  High speed camera work suggest the core goes first, see the disappearing bit in my avatar.

I have been further considering the heat conduction problem but reckon it is going to take several days of work to make a stab at solving the question, days I am afraid I currently don't have.  I think part of the problem about glazing may well be due to the low heat conduction of dry nylon, so the energy being generated is not dissipating quickly enough thus causing higher temperatures in the surface region of the rope to glaze it.  I think glazing probably occurs around nylon's melting point of 220C.  On the other hand, in the descender, the metal's high heat conduction means the temperature remains much lower.  But since generally people can't hold anything which is above 60C (don't try it unless you want to get a burn), one senses that the descender is extremely hot whilst in reality it is not hot enough to harm the nylon.

So far, we have been thinking about heat generation and the rope getting glazed due to getting too hot.  How about other aspects?  What about mechanical damage to the rope?  Is a wet (and muddy) rope more likely to suffer abrasion damage than a dry muddy rope?  And then there's the issue of handleability...

I don't think I can answer Rodger's questions except to say one needs to think very carefully about the mode of heat generation.  I keep getting different ideas about this and end up in a muddle.  We can take the extreme cases where all the energy passes into the rope or into the descender but they are extremes.  But how is the heat generated?  Is it a simple friction of one surface running over another or is it the muddy particles in the rope gouging the metal?  If it is the former, then my first thought (which is usually wrong) is that the energy ends up going into the higher heat conduction material, that is into the metal rather than the rope. 

I can start to see a interesting project here with sand paper of different grades.

 

[SamT]

Interestingly - no comment from any IRATA bods.  :-\

I'd have thought they'd have an in depth knowledge and experience of this.  Thinking about it - I can't recall any rope workers I've seen wetting their ropes. But then I guess they (well - the window cleaners) only ab in short sections of a few feet at a time, then stop to wash the window etc.

Still - be interesting to hear what they say - Robbie/Noz/Moose/Henry.....anyone......anyone...... Bueller...Bueller.

 

[pwhole]

Wear a Camel-pack and squirt water on it as you go down...?

 

[Roger W]

My ol' mate Sid likes descending very fast.

He always goes "Weeeeeeeee!" as he goes down.   

 

[pwhole]

I went down Elizabeth Shaft in Nettle (first time) yesterday on a bone-dry 10mm rope yesterday afternoon, so this thread was in my head as I descended. I took it steady, but didn't stop at all, and at the bottom the Stop was certainly hot, but definitely not too hot to touch. I weigh about 80kg, so pretty average really.

I would guess that rapid halts caused by panicking would probably generate more heat than a steady descent. To be honest, it was so pretty on the way down I didn't want to go too quickly anyway!

 

[CatM]

After abseiling on a dry rope at the weekend and subsequently burning my finger on my rack, I would most certainly advocate wetting ropes!

It was a 50 m pitch (Titan entrance) but I wasn't going particularly fast, yet I still have a pretty sizeable blister...

 

[Alex]

If its sunny where do you wet your ropes there? There used to be a handy barrel for that but of course that has gone now.

 

[Geoff R]

If its sunny where do you wet your ropes there? There used to be a handy barrel for that but of course that has gone now.

Suggestion .... wet the rope the night before and let it drain 

 

[Maj]

Simple answer.
Leave it as is from the previous trip.
Suddenly remember half an hour before the next trip.
Wash it just before you go.

Sort id !



Ooooh ! I can already hear sharp in takes of breath.
Only kidding  :tease:

Maj.

 

[pete_the_caver]

When descending Hardwood's Hole In New Zealand The Hamilton Tomo Groups policy for its rope was that it be rigged the day before it was required so that water running of the rebelay would wet it  or you rigged it wet.  this meant that you had a 156m free hang below the rebelay on wet rope and no sunsequent glazing.  As for loss off strength?  This was not a problem because it was polyester.

One question tho?  Is nylon caving rope dry coated as you find with some caving ropes?