Treemagineers Chris Cowell and Mark Bridge opened the dynamic lanyard debate at their Hamilton workshop early in August when they suggested the Trango Cinch was not suitable for use with either tree climbing lines or ultra-static Armor Prus.
Let's recap: the Trango Cinch is a compact belay device, designed for use with dynamic climbing lines certified to EN 892. It is NOT rated for tree climbing lines with the EN 1891A certification.
To compound the matter further, the Cinch lanyard of choice for kiwi climbers was typically made from ultra-static 10mm Armor-Prus because it ran nicely through the Cinch.
We have to remember, tree climbers are not using the Trango Cinch as it was intended. We are using it as a compact lanyard adjuster not a belay device, so some quarter was given on the choice of rope.
Under normal circumstances, a tree climbers lanyard operates with 'passive' loads applied. The extreme dynamic loads you could expect in rock climbing are less likely to happen with a tree climbers lanyard (given prudent climbing technique).
With that notion in mind, plenty of kiwi climbers accepted the compromise and continued to use 10mm ultra-static lines on their lanyards.
The debate may have ended there, but for a random photograph taken last weekend at the Waikato/BoP Regional TCC. The picture showed world footlock record holder James Kilpatrick's Treemotion harness sporting a Trango Cinch along with a dynamic lanyard.
The question tree climbers asked: was James operating 'by-the-book' or was there another reason why he might be using a dynamic lanyard?
The answer is a little bit of both.
When Treetools questioned James about the dynamic lanyard he told us, in his opinion, we should indeed be using a dynamic rope, as specified for the Trango Cinch.
But there was another reason.
During the tree removal competition at the World Arborcamp back in July (which the kiwi team won>) James noted excessive reverberation through his ultra-static lanyard as each piece was dropped into the impact block, even with correctly pre-tensioned loads.
The softest link in this 'chain' is your body, so all the reverberation energy will be concentrated into the small of your back.
Perhaps this is not a big deal if you are only doing a few drops but it is not pleasant over a long period.
By using a dynamic lanyard you can more-or-less eliminate the effects of stem reverberation altogether, making a take-down far more comfortable and safe since there is less chance of your gaffs releasing as the stem shakes through your body.
James Kilpatrick's Treemotion harness set-up with Trango Cinch and dynamic lanyard.