Say you like the idea of flat rappel knots, as they seem likely to slide easily over the terrain when you pull down the ropes — but also you remember hearing reports of flat knots rolling along the tails until the ropes came apart. Here’s a suggestion for securing your favorite flat knot without needing any extra equipment… using only the rope:
Flat Fig. 8 Showing Tails Lean One Way
The two tails often tilt in the direction of one rope or the other: make a half hitch in the rope in that direction and close to the knot, and pull the two tails through it. Snug up the half hitch against the flat knot, and carry on with your rappel, that’s all there is to it.
Flat Fig. 8 Secured With Half Hitch
The joining knot is still nearly as ‘flat’ as without the half hitch, while the hitch curbs any tendency of the knot to invert under tension. This was proven in testing to about 10X the weight of a climber, or some 15-20X the load that a rappel knot would normally withstand.
More information is available in the Safety page articles, under Resources.
Orvel
2 Comments
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Author
I should have mentioned that the half-hitch method works on all flat knots, including the EDK. The half-hitch hides behind the main knot and so does not increase the likelihood of dislodging debris, as a separate backup knot in the tails does. Also the half-hitch maintains the flatness of a flat knot, as its parts are alined with the ropes.
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This is an interesting idea, but I don’t think I’ll be adopting this for my own use. Most of the testing and research I have seen actually shows that a flat figure 8 will capsize at a lower load than a flat overhand, and as such is not recommended practice.
The arrangement shown here looks like it would be very likely to catch on rocks and either get stuck or pull loose rocks down on top of the team while pulling the rope, thus negating the reason for using a flat bend in the first place.
For slippery/icy ropes, I’ve just tied an additional overhand knot in one of the tails (which I always leave quite long). That doesn’t interfere with pulling the rope, but does provide some protection against the knot rolling.
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