Climb Safe: Rethinking the Double-Loop Bowline
Pity the double-loop bowline—it’s getting a terrible rap. In its defense, the double-loop bowline—the only knot that is truly easy to untie after a fall—has worked flawlessly millions of times for climbers and sailors worldwide. Yet, if the knot is causing accidents, maybe we should rethink it. Let’s examine.
Pity the double-loop bowline—it’s getting a terrible rap. We bagged on the knot because in 1989 Lynn Hill took a 70-foot groundfall when her partly tied bowline pulled free of her harness.
Sacrilege! Or not? In its defense, the double-loop bowline—the only knot that is truly easy to untie after a fall—has worked flawlessly millions of times for climbers and sailors worldwide. Yet, if the knot is causing accidents, maybe we should rethink it. Let’s examine.
According to Mountaineering: Freedom of the Hills, a bowline will reduce a rope’s strength 25 to 30 percent, compared to 20 to 25 percent for the trace-8. Considering that the typical tensile strength of a lead rope is upwards of 5,000 foot-pounds, either knot, even after it has weakened the rope, is plenty strong.
Ease of Tying
The double-loop bowline and the trace-8 are complicated knots that require practice. As Clifford Ashley noted in his 620-page The Ashley Book of Knots, “A knot is never ‘nearly right,’ it is either exactly right, or hopelessly wrong … ” Since tying both knots requires an equal skill level, a better measuring stick is to consider how the knots fare when you tie them the wrong way.
Typically, people screw up the bowline because they tuck the end of the rope down through the loops to begin, instead of out through the loops (Step 1). Make this mistake, and the bowline looks obviously wrong and tends to fall apart in your hands—but not always. In every documented case of double-loop bowline failure, the knot either wasn’t tied properly, or wasn’t cinched tight and not backed up.
Typically, people screw up the bowline because they tuck the end of the rope down through the loops to begin, instead of out through the loops.
The common way to incorrectly tie the trace-8 is to not completely rethread the 8, stopping the knot short of actually being tied. Then, the trace-8 looks almost right and holds itself together, giving the illusion that it’s been properly tied. In some cases, a partly tied trace-8 has even held weight, and the unsuspecting climber didn’t know he’d blown it until he was back on the ground untying.
Lesson: If you are going to tie a knot wrong, the trace-8 is the one to botch.
Assuming you’ve learned the knot, you can test its security by jiggling it to simulate the action of a rope as it’s repeatedly pulled taut, then slacked off.
Do this test and you’ll find that the trace-8 is the least likely of the knots to untie itself.
In this sense, the trace-8 is safer, but only because you are not using a back-up knot—a dangerous but common practice, especially among high-end climbers. Finish either knot with a back-up and they are equally reliable.
Numerous back-up options exist, such as the popular overhand and half-hitch, but the half-fisherman’s (aka grapevine) is superior. Although the half-fisherman’s eats up some rope and is bulky, it is unlikely to work loose, making the double-loop bowline and trace-8 blast proof. Best, the half-fisherman’s can, in the event you do incorrectly tie your main knot, even hold weight by itself.
In the end, both tie-in knots have merit. If you are going to tie in sloppily and not use a back-up, the trace-8 is king, being the least likely of the knots to come untied, especially in a stiff rope. But, tie in carefully, draw the knot tight and use a back-up, and the double-loop bowline remains a sure bet.
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To help make more climbers safer climbers, Rock and Ice has teamed up with Black Diamond Equipment to present the Climb Safe series.These articles aim to answer some of climbing’s most common gear-related questions. Here, Kolin Powick, Black Diamond’s Director of Quality, investigates a mysterious harness failure and dives into the effects of chemical contamination on climbing textiles.read more