[Dan Lehman]

Originally Posted by benz

Hi Dan,
I won't insult you by suggesting that you've never done a long series of rappels and thus don't know why the pulled rope alternates--I'll just say that I forgot the discussion was about ropes of different diameters.
//
an alternate pull on each successive rappel makes for maximum eficiency in my opinion.

But you could edify (for all of the readers)!
I still can't imagine why, and will note that it entails ensuring, each time that
the knot is on the proper side of the rap-ring/sling for the altered order.
Or is there some issue with torsion & kinking/rope-handling?
(But, yes, the OP is concerned w/thick-thin ropes.)

If as you suggest the EDK need be backed up by tying the smaller rope around the larger, we no longer have a perfect bend--we have one that requires a back-up and the extra bulk that that entails.

That's just a particular way of seeing this knot as compound or not --one could argue either way. As for bulk, it remains a compact small knot (the added overhand being in the thinner (or more flexible) line, and being half of what has been suggested by one of the above references --of repeating the base knot). And in either of these cases, one at least has a smooth-*flowing* *offset* knot.

To the question of the need for that, and of rope-pulling problems in general, I've seen the on-line discussions garner testimony such as Moyer's that there have been few if any problems (using whatever), and of those that occurred, a different knot wouldn't have mattered. .:. a big "YMMV" situation.

If you have not seen an EDK roll a little as it is weighted, I congratulate you on having partners who draw it up most carefully as they tie it: not all my partners have been so [careful].

But there is something inconsistent with remarking that as simple knot as the EDK cannot be assuredly tied while urging that a rather non-simple Butterfly bend be used instead! To my mind, it is better to retain *extant technology* (here, the overhand) and infuse in its use the purpose of its parts --being offset (and easily/quickly tied), being drawn snug with special focus on the part making the initial choke (where the thinner line should be) which is the line to be tied-off around the other's tail, for surety.

I would not call all the above-named bends novelty knots: most have existed for longer than climbing has been popular, and the climbing world still has much to learn from the sailing and rigging world.

Those I had in mind would be the butterfly & zeppelin end-2-end knots --though the former, in eyeknot form, was known 1928 even in one climbing source and regurgitated by Phil Smith's ca. 1960 book, and the latter seems to have surface ca. 1970 (its history w/airships being doubted), neither has been of much note in any practical application. And, of course, Ashley's quite like knots #1452 & #1408 (and the more slack-secure #1425!) saw daylight of published knots by 1950, but are scarce "in the wild," to my awareness. The cordage of sailing and climbing differs. Sailors have no qualms about using a bowline w/o further precautions; climbers had better add some security!

My favorite bend for rappel ropes is still the Strait Bend, ... it is the one I will always use. Does a nice job with docklines, too.

Ben, why not Ashley's #1452, 1408, 1425 or the zeppelin? It struck me as odd to use the butterfly in a situation when its asymmetry wasn't necessary (for tying) --go for a symmetric knot!
As for butterfly orientations, what looks best to me I think is crossing the tails, where --from the perspective of the knot w/tails UP, standing parts entering with first crossing UNDER their collars --and so then being horizontally parallel--, to have the LOWER line's tail be oriented adjacent to its standing part, the other tail crossing behind it. This makes the lower line's overhand take a *pretzel* form, and the other's a sort of *minimal timber hitch* form. The curvature of both lines into the knot looks good, and it seems to retain the easiest form to untie.

--dl*
====

ps:

... is to lead with two 3/8" ropes ...

Oh, how yesterday !! Hip, modern climbers are much sharper, able to discriminate between fractions of a millimeter --"Would a 9.4mm be okay, or should I carry a heavier 9.8mm ... ?!" !! (Older climbers cannot resolve as fine as even a whole millimeter, let along fractions thereof.)