Talk:Anchor (climbing)/Archive 1

Archive 1

Proof

I've removed the following section content (and reused the secn hdg for this secn):

Defining the vertical and horizontal components of the anchor force as $F_{a}^{V}$ and $F_{a}^{H}$ (respectively), we see that

$F_{Load}=2F_{a}^{V}$, (1)

or, rearranging,

$F_{a}^{V}=F_{Load}/2$, (2)

Furthermore, from trigonometry, we know

$\cos(\theta _{V}/2)=F_{a}^{V}/F_{anchor}$, (5)

and thus

$F_{a}^{V}=F_{anchor}\cos(\theta _{V}/2)$. (6)

Finally, equating equations (2) and (6) and solving for the anchor force, we arrive at

$F_{Anchor}={\frac {F_{Load}}{2\cos(\theta _{V}/2)}}$. (7)

Such a proof may be appropriate to a trig or physics (statics, classical mechanics) textbook, but certainly not in this or other specialized application articles. It may be appropriate to a WP article in one of those areas of theory, tho that's not obvious either.
What defintitely is desirable here is at least one lk to an article on vector components and/or trig principles.
--Jerzy•t 07:27, 7 August 2008 (UTC)

Equalization

This is a valuable but flawed treatment.

1. "Anchor" is used ambiguously and inconsistently, for each of the individual features found at the site and to the single integrated structure they and your anchor-building gear are combined into.
2. The diagram is ambiguous in failing to indicate whether the loading is roughly horizontal between the trees and the vertex and becomes roughly vertical down-screen from there, as is typical for top-roping; if the vertex is significantly uphill from the idealized precipice, you've settled for a wider angle than you can get (if your anchor lines are long enuf); if it's significantly downhill, you've presumably shortened the climb and ruled out topping-out (or doing so safely). Presumably a horizontal dashed line, explained as corresponding to the idealized cliff edge, would make all the difference.
3. The "never" in

   An angle this large should never be used.

   assumes what is unknowable, that the two natural features are equally strong. If one should barely fail in a (symmetrical) 120° setup, bcz it is the weaker, you have an extension problem, but the redundancy means you've made use of the stronger even tho you didn't intentionally test the weaker to destruction.

4. A geometry with two equal angles to the combined load is assumed; that is crucially valuable as an illustration, and in practice, usually as an approximation, but there should be at least one example that at least hints at the realistic situations where, for instance, one feature is directly "behind" the top of the climb and one is 30° or 50° off to one side; note especially that a feature 50° off has to be as strong as each in a symmetrical 100° setup would, even tho the diagram and table invite the impression that the 50° angle between the two legs is all that matters.

--Jerzy•t 07:27, 7 August 2008 (UTC)
 Section finally rewritten (after 8 years), image replaced. Hadron137 (talk) 20:42, 28 March 2016 (UTC)