RAD LINE joining knots - Petzl United Kingdom
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RAD LINE joining knots

Tests of joining knots useful for rappelling and glacier travel.

Warnings

  • Read the technical notice before viewing the following techniques.
  • It is important to fully understand the information provided in the technical notice before using this complementary information
  • Mastering these techniques requires training.
  • Consult a professional before attempting to perform these techniques on your own.

1. Joining knot for rappelling

Pull test, two ends of RAD LINE joined together.

Pull test, two ends of RAD LINE joined together.
Figure-eight knot: strength greater than 12 kN.

Figure-eight knot: strength greater than 12 kN.

Flat overhand bend: knot slips at 7 kN, then the rope is released.

Flat overhand bend: knot slips at 7 kN, then the rope is released.

 

The flat overhand bend is strong enough for the forces in a normal rappel.

The figure-eight knot, which is stronger, is generally prohibited for this use because of its tendency to capsize. This effect was not observed on RAD LINE, no doubt due to its flexibility. 

WARNING: the values above are valid only for the RAD LINE, they could be very different with any cord of a different diameter or material, especially in the case of cords with a more slippery Dyneema sheath.

 

2. Joining knot for roped progression

Pull test, two ends of RAD LINE joined together.

Pull test, two ends of RAD LINE joined together.
Double fisherman's knot: cord breaks at 9 kN.

Double fisherman's knot: cord breaks at 9 kN.

Figure-eight knot: cord breaks at 10 kN.

Figure-eight knot: cord breaks at 10 kN.

(Knot begins to capsize at 7 kN, then the knot tightens).

Flat overhand bend: cord breaks at 8 kN.

Flat overhand bend: cord breaks at 8 kN. (Knot begins to slip at 4 kN, then the knot tightens).

 

All of the knots tested are strong enough for the loads recorded during the crevasse fall testing.

It may be interesting to take into account the volume of the knot that helps create friction against the lip of the crevasse.


Technical tips