Swiftwater Rope Testing - Wet and dry rope strength
In June we ran a series of rope tests to see how rope systems stand up to typical swiftwater rescue uses rather than the mountaineering or industrial uses that they are tested to for the european standards. Our first test was to see if the strength of ropes changed when wet and by how much. We tested nylon semi-static ropes, polypropylene throwbag ropes, nylon/polypro canyoning ropes and dyneema/polypro throwbag ropes. Used ropes were tested to see how much age made a difference between the results and the manufacturers specifications.
Method: Short lengths of rope were placed in the testing rig with a figure of eight knot in each end and then pulled to destruction. The first test was with a dry rope then the test was repeated with a wet rope.
Here the results of the tests have been placed in a table along with the manufactures specifications for the ropes tested.
| Rope | Age | Material | Strength | Strength 8* | Test 1 | Test 2 | Change |
|---|---|---|---|---|---|---|---|
Edelrid Superstatic 11mm Red |
7 years |
Nylon |
31.0 |
23.0 |
16.66 |
13.65 |
-18 % |
Lanex Static 11mm White |
Brand New |
Nylon |
40.0 |
15.0 |
23.30 |
19.29 |
-17 % |
Lanex Static 11mm Black |
1 year / worn |
Nylon |
40.0 |
15.0 |
15.60 |
13.52 |
-13 % |
Edelrid Canyon 11mm Orange |
7 years |
Nylon + PP |
18.0 |
12.0 |
11.98 |
13.79 |
15 % |
Edelrid Canyon 9mm Yellow |
8 years |
Nylon + PP |
9.0 |
8.0 |
7.08 |
6.82 |
-4 % |
°hf KM 7.5mm Throwbag rope |
4.5 years |
PP |
8.4 |
4.9 |
3.06 |
3.89 |
27 % |
°hf PPM 8mm Throwbag rope |
12 years /worn |
PP |
11.0 |
5.5 |
4.52 |
4.90 |
8 % |
°hf PPM 8mm Throwbag rope |
20 years |
PP |
11.0 |
5.5 |
3.85 |
4.25 |
10 % |
°hf KM 10mm Throwbag rope |
1 year |
PP |
13.0 |
7.6 |
8.27 |
8.84 |
7 % |
°hf Syntec 7.5mm Throwbag rope |
1 year |
HDMP + PP |
24.0 |
10.7 |
10.02 |
10.58 |
6 % |
Strength is the tensile strength from the manufactures specifications, without knots.
Strength 8 is the min. manufacturers results for knotted tensile strength *(throwbag rope values with an overhand knot).
Test 1 is the dry test with figure of eight knots.
Test 2 is the wet test with figure of eight knots.
Change is the percentage change between the first and second tests.
Conclusions: All the nylon ropes were on average 16% weaker when wet than when dry. However, when new and dry, they are best ropes for applications like high lines where high strength is required. A big surprise was that the Polypropylene ropes are actually stronger wet than dry! The Edelrid 11mm Canyoning rope was stronger than the Edelrid 11mm Superstatic when both are wet, even though the Superstatic is 11kN stronger when new and dry. The 9mm Edelrid canyoning rope, owing to it's high proportion of Nylon (sheath percentage of 47%), did not fair so well when wet being outperformed by the newer 10mm throwbag rope.
Unfortunately all the used ropes tested had lower strength values than new ropes (some a lot lower), reminding us that if we want our ropes to perform to their limits, then we had better replace them often. Even a new looking old throwbag rope performed much worse than a newer well worn rope.
These tests were performed in cooperation with Axel Manz. Many thanks to Bonack for allowing us the use of their excellent testing facilities.
info@swiftwaterrescue.at