... which knot to use ... and how to tie that particular knot
I emphasized "particular" because it's more important to first sketch the
general cordage structure you might employ, and even then there might
be several knot-solutions to your rope-problem.
My application is for bodyweight exercises.
I have an online example of someone using straps and sewing loops on the straps to have different lengths.
I think I could do this cheaper(possibly better?) if I used rope instead of straps. Would do you think?
Webbing (straps) can be kinder on the body, having a broad surface;
but thick rope can also be fine. You might experiment putting some
pressure by yourself to see how different materials feel. Right now,
I'm thinking of a solution that uses rope as a tension member but
has webbing making human contact -- but certainly the latter could
be replaced with rope (not so well the former, though!).
{H}ow would I tie loops in the rope so as to adjust the working length of the rope?
Is it possible to use the same length of rope and just tie a number of loops
so I can adjust the working height by simply placing my carabiners in the appropriate loops?
My idea is simpler, more flexible (I think):
- The support comprises a rope for attachment to the anchor, long enough for all;
- then attached to that are slings (circles/loops ...) of webbing, which can be adjusted
to whatever position along the rope is desired, tied to the rope with friction hitches.
And one could of course have more than one sling attached per rope,
if that seemed to facilitate the structure's use (or in case of many-limbed
users!
).
For the friction hitches for the slings, I'd try a novel knot I'll a ProhGrip
Sling hitch -- just like the Klemheist (Google), except that the penultimate
wrap of the to-be-loaded end should (also) pass through the supporting
/ locking bight as will the final wrap. I think that this knot might give a
better stability than the Klemheist.
Now be advised that knots simply don't come with a guaranteed set of
properties; or I should say that such physical properties don't narrowly
attach to knot schemas? -- materials matter! What might work in
thistape on
that rope well could be not so good on some other combination.
In the case of the friction hitch indicated above, you might simply need
to adjust the number of wraps that are made (I think that the Klemheist
is often recommended with four or more?).
Also, tape/webbing, of an appropriate 9/16" or 1" tubular (rockclimbing
sizes) should grip pretty well on 3/8"-1/2" rope; but if those slings are
of rope, which you'd want to be reasonably thick for taking had pressure,
gripping becomes more of a challenge. Conceivably, you might construct
the slings of two materials, a thicker one for comfort joined to a thinner
one for gripping. Depending upon your overall needs, a single rope
could work, with its "loop" formed by turning back upon itself with
e.g. a Blake's ("ProhGrip" my nod to Prohaska) hitch closing this now
adjustable eye; but raising the knot say 2 feet will raise the eye just
1 foot -- can such a structure work for you?
Heck, alternatively you could have one big circle that is of rope
tied to itself, and then adjust its circular size by sliding the rope
through the closing friction hitch. -- and something akin to what's
called the "Purcell Prusik" (Google -- maybe w/options on the (mis)spelling
of "Prusik": often 'prussic', 'prusick', 'prussik' ... ), which is sometimes
used as a structure with an eye (longest reach) and other times as the
closed circle just described (smallest reach; eye-size small).
--dl*
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