Cavechat.org

ian mckenzie wrote:Google says anywhere between 5 and 10%, which is consistent with my experience.

I agree. Back in Italy we used to consider 10% as standard, even if actually was something less than that. But static ropes like Elderid (a brand widely used in Europe) are also way more dynamic than some static ropes used here in the US.

About wet the rope, exp. if new, we used it to avoid heat damages. Infact the water tend to "absorb" the heat generated by the rappel and this isn't passed on - or is at lower rate - to the rope. Used exp. on long ropes even when not brand new. On brand new rope, excellent to wash away the soap.
BUT...BUT I've been also told (by a friend who's also a climber) that a wet rope might loose some of its dynamic properties: it's up to the single rope, brand and its history of usage.

As for the shrinkage, I have been told that is mostly caused by the sheat getting tighter on the core. That's why sometime on brand new rope sheat slippage could be experienced.

My cent -- Renato

One of my buddies bought 300' of rope last weekend. PMI Pit Rope, 11mm. When he got it home, he measured it to be 296'. He then soaked it in water for two hours. After it dried, he remeasured it and got 283'. 4% shrinkage rate. He's going to use it this weekend at a 200'+ drop which should stretch it back out a bit. I'll report back with the new measurement.

BTW, when he bought it, he pulled an extra 8' off the spool to account for shrinkage and still ended up 4' short. Maybe the rope measurer thingy that you pull rope thru was not calibrated properly?

I tend to pull an extra 10 feet for the just in case scenarios and to account for shrinkage.

I just had an interesting experience with some Bluewater 9.5mm.
I'd bought the rope some years ago, and thoroughly soaked/dried it multiple times before cutting and marking it.
The ropes had each been used on a few trips, but one 45m rope wasn't getting much use, so I decided to chop it to smaller lengths. When I came to measure it, it was a shade under 40m, and two other lengths - marked as 36m and 32m were each a little under 4m short.
So, it seemed like even after the initial soaking, the ropes lost a little more than 10% of their length.

With Edelrid 10mm, which I've soaked a fair few reels of over the years, it generally seemed that the initial multiple soaking/rinsing and drying cycles caused about a 5% shrinkage, with another 5% happening during early use.

potholer wrote:I just had an interesting experience with some Bluewater 9.5mm.
I'd bought the rope some years ago, and thoroughly soaked/dried it multiple times before cutting and marking it.
The ropes had each been used on a few trips, but one 45m rope wasn't getting much use, so I decided to chop it to smaller lengths. When I came to measure it, it was a shade under 40m, and two other lengths - marked as 36m and 32m were each a little under 4m short.
So, it seemed like even after the initial soaking, the ropes lost a little more than 10% of their length.

With Edelrid 10mm, which I've soaked a fair few reels of over the years, it generally seemed that the initial multiple soaking/rinsing and drying cycles caused about a 5% shrinkage, with another 5% happening during early use.

My club has experienced the same shrinkage issue especially with Lanex rope.

Well since this thread held some interest for me I thought I'd do some 'sperimentin' of my own!
One new piece of PMI 11mm Pit Rope measured with a survey tape to 220'
went caving right off the spool, no pre soak or wash just a little water in the cave, about 3 rappels and climbs for most of it's length. The rope was then washed off a day or 2 later with a garden hose, well soaked, cleaned and hung to dry for about 2 weeks. Prior to the next need for the ropes assistance it was measured to be 208' and then rigged again in a pit and rappeled and climbed once for most of it's length. Said rope was carried home and measured to be 209'. So... since it was 220' and then became 208' and now is 209' we lost about 11-12' which is like 5.45%. I will measure it again after a few caving cycles and see what happens but I think it is a 208/209 footer permanently or really a 200ish which is what I was looking for in the first place. Interesting.
Mike Hopkins

I retired a Petzl Vector after about two years of use, 150' shrunk to 133.4 or 9%. This was without being soaked before use, but a good wash after each hard I.E. caked in mud use. I wonder if use shrinkage and soak shrinkage differ?