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Etiquette of contacting Nice Guy Dave (have some in-depth cordage Q's)

eye.heart.trees

eye.heart.trees

arborjunky
Joined
Jun 25, 2019
Messages
69
Age
38
Location
Tampa-Area
I frequently hear that you can actually reach out to him in fact on a Climbing Arborist podcast the host (Dan?) was mentioning how you can contact him and (paraphrasing) "Ask him anything about rope, there's nothing he doesn't know about rope that is worth knowing!"

I've got some 'meta' questions on rope as I choose the last component for my "heavy duty rigging system", a 5/8" bull line, in the searching I found just how terribly under-spec'd these lines are at least in the magazines&websites (from missing data to conflicting data it is just insane how little is shared to the consumer here :/ )

So ---- have you called Dave to talk ropes? Was thinking maybe it's smarter to email him first but unsure if I'm making a mountain out of a mole-hill, I mean if he's as knowledgeable as I'm hoping then 5min on the phone should be enough to enlighten me!!

Am also eager to hear if anyone's found anywhere else that's authoritative Re ropes and the varying fibers used to create them, Yale is a go-to for me so I intend to contact them via email (again) to get to the bottom of my Q's but any reco's besides Dave or Yale would be greatly appreciated, thanks :D
 
eye.heart.trees

eye.heart.trees

arborjunky
Joined
Jun 25, 2019
Messages
69
Age
38
Location
Tampa-Area
Since I'm posting in this sub & in this context, figure it can't hurt to outline my queries in the open here:

1 - How varied are the strengths of the nylons, and the poly's, that are used in climbing/rigging lines? The HMPE ('ultrahigh molecular-weight polyeth.) designation in the Wesspur catalogue describes dyneema/spectra, yet Yale's website describes the Yalex/Tenex cordage as being an HMPE poly, however Yalex/Tenex are >1% stretch unlike real dyneema/amsteel at like 0.4% or 0.5% stretch...am presuming Yalex/Tenex is a poly+HMPE mixture but would like to understand what makes the Yalex/Tenex fibers so much stronger w/o going <1% elasticity.

2 - Elasticity... I'm very surprised by, and want to understand the reasoning for, the fact that climbing lines are more-elastic than rigging lines, this seems utterly nonsensical to me I mean we want static-feeling performance (ie you don't want to feel slop/bounce) when climbing, it's fair to say (rigth?) that we'd use amsteel for climbing EXCEPT that too-static is unsafe because it doesn't tolerate dynamic use (which is basically EVERY USE CASE for us, whether the gentle ~2X bodyweight force we exert on a line when ascending SRT, or the god-knows-what-% that we're exerting by snubbing a 500lbs log to a halt after a few feet of free fall) so we have climb lines that are 1-->3% average, compared to the bouncier rock-climbing lines that are near/around 10% because taking shock-loads of you falling into them is expected/what they're built for. BUT, for rigging.....Why on earth are the lines so static, averaging less-elasticity than our climb-lines? For a climb line you just want enough to not make the rope dangerous, past that you want it to 'feel' static, but when you're controlling a log that gravity is bringing to the ground, whether well-controlled positive-angle rigging or violent negative-angle blocking&snubbing, the uses are inherently dynamic, so why are such low elasticity%'s the norm? On this note, I'm shopping for 5/8" right now, stuck between Atlas & Polydyne (though I'm quite sure the latter will be my choice), and I couldn't help but notice that both Yale and Samson, the two biggest names, are both upping the elasticity as they introduce new lines (nystron after Stable for samson, Polydyne after D.Elasteron for Yale), I'd say "great!" because the lines seemed sub-optimal when so static BUT how on earth are the biggest manufacturers JUST-NOW getting their elasticity up? I'm new enough to this industry but would've guessed that "optimal elasticity for bull line" would've been a topic that was beaten to death *decades* ago, I mean how on earth could that much rope get made & used and the optimal elasticity is still being eeked-towards?
(On this ^ topic, would it be fair for me to say "When considering bull-lines for rigging a dismantle-the-tree job, if one knows the materials used in the line *AND* the line's weight-per-100', then elasticity figures are more valuable information than static-MBS", it seems to me that it is because the elasticity is characteristic of the shock-absorption graphing the rope can take as it's progressively loaded through the log's descent, whereas static-MBS can be wildly misleading since a super-high-MBS rigging line made of Amsteel would make one think they can block heavy stuff onto it, when in reality it's a snap-risk to do so!)

3 - I'm thinking that it's silly to choose yalex/tenex over double-braids for slings, my logic is that since it's part&parcel with your bull line for rigging a limb there's no reason to think "it's fine to have a super-static cordage as a sling, in a system where I've chosen a more dynamic rope say 4.5% Atlas", in fact since the sling is so short (less rope for shock-absorption) you'd think that a slightly MORE elastic cordage would be used (IE if coming up with 'the norm' myself I would say slings should be at least 25%-->33% thicker than the cordage and at least 0.5% more-elastic, both for accounting for the fact that the anchor-sling simply doesn't have the length to absorb shock like a full line does)

4 - What is the (or one-of-the!) most thorough equations that can be used for calculating peak-load on a line? I've seen a formula in the past that included rope-length and elasticity, but for the life of me cannot find it or get anyone to link me - really need that formula however anything else in this regard would be helpful (IE the formula is only for *peak* load, while real-life has the run-up to the peak force, so you can be more accurate than peak-load calculations however I dunno if that's possible w/o a computer/software for analyzing it :/ )

Well we'll see, think I'll shoot him(or their .info url or whatever they've got for Contact!) an email today as a 'heads-up' that I want 5 or 10min to ask these, probably better to just offer him my # and say I'll take his call whenever he sees fit (am nervous LOL, watched all his videos explaining basics when I was starting out!!)
 
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