Ascender Safety 101

       Ascending Rappel Ropes 101

       Autoblock Misuse (ATC-Guide)

       Avalanche Safety

       Belay School - Why Dynamic Matters

       Can A Hot Belay Device Melt My Slings?

       Carabiner Off-Axis and Tri/Quad-Axial Loading

       Choosing the Right Carabiner

       Common Belay Screw-ups

       Connecting Two Slings Together

       Daisy Chain Dangers

       Dangers of Rope Worn Carabiners

       Dangers of Worn Lowering Anchors

       Do Ropes Need to Rest Between Falls

       Draws in a Gym

       Extending a Cam Sling

       Fall Factors Explained

       Full Strength Haul Loops

       Gear Doesn't Last Forever—Crampons

       Gear Doesn't Last Forever—Ice Tool Picks

       Gear Doesn't Last Forever—Slings & Draws

       How Sketchy Is a Sharp-Edged Carabiner?

       How Strong are Himalayan Fixed Lines?

       How to Belay, Part 1

       How to Extend a Rappel

       How Strong is the Spinner Leash?

       Knot Passing 101

       Rappelling - Climbing's Diciest Business

       Re-Slinging Cams

       Retiring Old Ropes

       Rethinking the Double-Loop Bowline

       Sharpie for Marking the Middle of a Rope?

       Sling Strength In Three Anchor Configurations

       Spectra versus Nylon

       Spotting for Bouldering

       Surviving Bad Weather on El Cap

       The Dangers of Modifying Your Gear

       The Dangers of Short Static Falls

       The Electric Harness Acid Test

       The Skinny on Super Light Ropes

       To Screamer Or Not To Screamer

       Top Roping is Not So Safe

       Weakness of Nose-hooked Carabiners

       What is the Safest Rappel Knot?

       Worn Belay Loops and Retiring a Harness

Video Spotlight
Nick Bullock and Paul Ramsden Make First Ascent of Nyainqentangla South East
Nick Bullock and Paul Ramsden Make First Ascent of Nyainqentangla South East

Climb Safe: What is the Safest Rappel Knot?

20-Mar-2015
By Kolin Powick

The following article is courtesy of Black Diamond Equipment.

Double Fisherman's Knot.I was climbing in Yosemite last summer and, while at a belay, was talking to a party from Bozeman, Montana. They noticed all the proto gear on my rack and deduced that I was from Black Diamond. My partner and I bailed (typical) and they were watching me like a hawk. I asked what they were looking at, and they said, "We want to see how the QA guy from BD raps." In particular, they were eyeing my rap knot.

There are advantages and disadvantages to each type of rap knot, but is there one that is superior in strength to the others? I put all three knots (with three different rope diameter scenarios) through a quick-and-dirty series of pull tests and have provided below some basic strength testing data based on my limited testing of the three most common rappel knots. (Note: only two data points per configuration.)

OBSERVATIONS
  • The Double Fisherman's and Ring Bend had similar strength results
  • The Euro Death Knot was the weakest: ~20-30% less than the Double Fisherman's and Ring Bend.
  • The Euro Death Knot slipped a bit before failure at ~4000 lbf with the 10.2 and ~2000 lbf with the 8.1 in the system.

Euro Death Knot (i.e. overhand). Ring-Bend Knot.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

BOTTOM LINE

QC with KP rap knot chart. CLICK TO ZOOMThe reality is that all three of the methods for joining two ropes for rappelling that I tested were PLENTY strong for the forces seen during a typical rappel (i.e., bodyweight-plus, taking into account some shock loading when bouncing around, jiggering with tangled lines, not smooth rappelling technique, etc).

For what it's worth, when I started climbing I always used the Double Fisherman's, but now I've fully converted to the Euro Death Knot—it's fast to tie, plenty strong, less likely to get hung up when pulling and easy to untie. And finally, no matter what rap knot I tie, I always leave long tails (like at least 12 inches).

Climb safe,
KP

Related Articles:

Climb Safe: Do Ropes Need to Rest Between Falls?

Climb Safe: Retiring Old Ropes

Climb Safe: Can A Hot Belay Device Melt My Slings?

 


Kolin Powick (KP) is a mechanical engineer hailing from Calgary, Canada. He has over 20 years of experience in the engineering field and served as Black Diamond’s Director of Quality for over 11 years. He is currently their Climbing Category Director. If you have a technical question for KP, please email him at askkp@bdel.com and he will TRY to respond.

To help make more climbers safer climbers, Rock and Ice has teamed up with Black Diamond Equipment to present the information here.

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