Canyoneering Rope Shrinkage Tests

How much do ropes shrink as we use them? There is no standard test for this, so it becomes very hard to say. I think/guess/observe/no-really-it-is-a-guess about 5% in the first few trips, and not much past that. For my Imlay Canyon Gear ropes that are 100% polyester, sheath and core, thus perhaps more resistant to shrinkage than other ropes. But what is really true? Could we actually collect some data and find out?

I will list and update the data collected here, with generally the latest data on top.

Rope #2 - Imlay Canyon Fire Rope, 120 foot nominal length. Put in service 6/2/2017

122 feet 0 inches - original carefully measured length.

6/3/2017 - Full Imlay with 4 people/4 ropes, this being one of them. Wet and dry.

118 feet 10 inches - first canyon loss of  2.6 %

6/15/2017 - Holy Grail: 4 raps, dry, 4 people; NaGah: 5 raps, mostly dry, 4 people, 2 ropes; DasBoot/Sub: 4 raps, very wet, 2 people.

117 feet 8 inches - second usage overall loss of  3.55% (still a slight bit wet)

Rope #1 - Imlay Canyon Fire Rope, 120 foot nominal length, Put in service 6/20/2016

121 feet 0 inches - original carefully measured length

6/21/2016 - Imlay Sneak route w 3 ropes, 5 people.  Wet and dry.

118 feet 8 inches - first canyon loss of 1.9 %.

unfortunately, this rope was coreshot in the canyon, and reduced in length, and I stopped using it to measure shrinkage...