Testing Dyneema Grog Loops and how to splice them


How strong is a Grog Loop? How do you tie them? Will a different length tail burry affect strength? Can you make small loops? We broke some to find out what works, what doesn't, and help you decide if Grog Loops will work for you. So what is a Grog Loop? It is a very strong sling made with hollow braided rope like Amsteel. It is quick and easy to make because the buried ends do not have to be stitched. It utilizes a Locked Brummel Splice that stays visible, so it is easy to check if the buried ends have begun to pull out. It is recommended that the tail loops be 30 times the diameter of the material, that limits how small a Grog Loop can be. We tested configurations with much smaller tails to see if we can make small loops that are super good enough. Theoretically, a grog loop should be about 140% of MBS. However, our tests showed that it isn't always the case. Because the tails are not sewn in a Grog Loop it is important to check on the loops after repeated loading, and it's probably a good idea to sew them as an additional safeguard if you can.


The Data


Jake Monaghan tested 5 grog loops made of 7/64 Amsteel. His results show that longer tails were stronger but all of them broke above the theoretical 140% of MBS.


He sent us six 5mm and six 6mm Grog Loops to test on our Slack Snap Machine. Our results didn't quite match up with his.

We got a wide range of results. In 5mm and 6mm it's to have 30x tail to diameter. When we didn't the Grog Loops broke below MBS. We only achieved 140% percent on 3 out of 12 Grog Loops. However, 4 of the 12 loops had insufficient tails.


Takeways


  • Make sure you have 30x tail to diameter for optimal strength

  • Keep an eye on Grog Loops to make sure they are not slipping after repeated loading, luckily they are easy to check

  • Our tests are not conclusive. Grog loops are relatively new. You should research and test Grog Loops before trusting your life to them.

  • Dyneema is weird and doesn't always behave the way we expect it too, especially in slow pull tests.

Check out the links below for articles on tapers

Extremegear.org carries a wide variety of Amsteel Blue SK75.


Here's a tech sheet on Amsteel Blue.



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