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