International Guild of Knot Tyers Forum

General => Practical Knots => Topic started by: Seaworthy on July 04, 2014, 08:40:04 PM

Title: Are there 2 correct ways of dressing the Alpine Butterfly?
Post by: Seaworthy on July 04, 2014, 08:40:04 PM
The Alpine Butterfly bend and loop seem to be able to be dressed two ways (with vertical sections either side of the parallel line or the X). Wikipedia shows the first in its main photo and further down the page it gives the other side of the other version.

To my eye only one looks right (the first), but it does tend to take longer to dress it this way.

Are both versions acceptable?
Are both equally strong?
Are both equally easy to untie after load?
Title: Re: Are there 2 correct ways of dressing the Alpine Butterfly?
Post by: Seaworthy on July 05, 2014, 04:16:57 AM
This is the way the Alpine Butterfly bend is usually shown dressed:
Title: Re: Are there 2 correct ways of dressing the Alpine Butterfly?
Post by: Seaworthy on July 05, 2014, 04:21:03 AM
This is the alternative way of dressing it. It seems to fall into place much more easily this way when tightening the bend up. It does, however, look a bit ugly to me.

The second image is occasionally the version presented online when this bend is being illustrated.

Are both ways of dressing the ABB acceptable?
Title: Re: Are there 2 correct ways of dressing the Alpine Butterfly?
Post by: Dan_Lehman on July 06, 2014, 06:41:58 AM
The Alpine Butterfly bend and loop seem to be able to be dressed two ways
...

Are both versions acceptable?
Are both equally strong?
Are both equally easy to untie after load?

As I wrote long ago, here (server with images/msg.
seems unable to respond; I have the images myself):
http://igkt.net/sm/index.php?action=profile;u=223;area=showposts;start=1380 (http://igkt.net/sm/index.php?action=profile;u=223;area=showposts;start=1380)

Will it be disquieting to point out that "there are about six ways"
in which the "butterfly" can emerge from its cocoon (excluding Layhands's) ?!

The tails can be "parallel", uncrossed; or they can be crossed,
in either of two ways; and for each of these orientations there
is the choice of which end to load, to make S.Part !

Here are two crossings.  We can refer to one overhand component
as taking the "pretzel" form, the other the half- or timber-hitch form.
That shown by David's orange rope takes the timber-hitch form, in the
*split* crossing orientation (my quick term, meaning that this S.Part
doesn't bite & draw its own tail but the opposite side's tail (such as we
can view them qua "tails" for the moment)).

See attached photos, fresh from the SDHCard.
//

And I've added a 3rd pic I think not in orig. post,
but I'm not sure.
In any case, the first is slightly exploded and with
different ropes, to help see the structure.
The 2nd is in one rope, and it is the 1st's orientation
now tightened.
The 3rd presents two crossings-orientations adjacent
for comparison.
As for yours, it looks like you're trying to get
a jammed knot!

As to Which is stronger? there is the standard response
that strength differences won't amount to a significant
matter, but --heck-- it should be obvious enough
that testers haven't even figured out that the knot
in being asymmetric needs testing to address that
aspect as well, so who knows what actually has hit
the test bed and yielded some numbers,
in some cordage, pulled some way, and ... so on.


--dl*
====



Title: Re: Are there 2 correct ways of dressing the Alpine Butterfly?
Post by: Seaworthy on July 06, 2014, 09:39:43 AM
......Will it be disquieting to point out that "there are about six ways"
in which the "butterfly" can emerge from its cocoon (excluding Layhands's) ?!

The tails can be "parallel", uncrossed; or they can be crossed,
in either of two ways; and for each of these orientations there
is the choice of which end to load, to make S.Part !

Many thanks Dan. I was hoping you would respond.

Yes, it is disquieting LOL. I can see how the tails can be crossed over at the end, but I have never seen it presented this way in "standard" images seen on the internet. 

Dressing it with one or both of the tails being the standing part gives a truly ugly knot. I have in fact loaded it on my winch as a loop using the loop and either of the other bits as the standing line and it jams appallingly on one of the overhand (I could not even undo it with a marlin spike).

As for yours, it looks like you're trying to get
a jammed knot!

Which of the two ways I presented of dressing it do you think it will jam? The second one? That is the one that would raise alarm bells for me, even though it is in use.

I dress the Alpine BB as in the first two photos in post #1.

As to Which is stronger? there is the standard response
that strength differences won't amount to a significant
matter, but --heck-- it should be obvious enough
that testers haven't even figured out that the knot
in being asymmetric needs testing to address that
aspect as well, so who knows what actually has hit
the test bed and yielded some numbers,
in some cordage, pulled some way, and ... so on

I will see if anyone in the crusing community with access to load testing equipment can test out the strength of the various ways the Alpine BB can be dressed. If so, I will report back.
Title: Re: Are there 2 correct ways of dressing the Alpine Butterfly?
Post by: Dan_Lehman on July 06, 2014, 08:55:06 PM
......Will it be disquieting to point out that "there are about six ways"
in which the "butterfly" can emerge from its cocoon (excluding Layhands's) ?!

The tails can be "parallel", uncrossed; or they can be crossed,
in either of two ways; and for each of these orientations there
is the choice of which end to load, to make S.Part !

Many thanks Dan. I was hoping you would respond.

Yes, it is disquieting LOL. I can see how the tails can be crossed over at the end, but I have never seen it presented this way in "standard" images seen on the internet. 

Dressing it with one or both of the tails being the standing part gives a truly ugly knot. I have in fact loaded it on my winch as a loop using the loop and either of the other bits as the standing line and it jams appallingly on one of the overhand (I could not even undo it with a marlin spike).
1) "never seen it presented this way" should be
put up in LARGE FONT as an emphasis NOT on
some sort of consensus but on the all-too-typical
parroting that cheapens (esp.?) knotting literature
--it can be amazing, and appalling (errors replicated, i.e.)!

2) "of the tails being the S.Part" : I think there might
be some confusion here, re what I wrote ("which end");
what I meant was "end" qua part-of-knotted-lines that
exits the knot ("nub").  I.p., in the linesman's loop
there are --as for any eyeknot/end-w-end-knot-- 4 "ends"
as such; and just one "tail", though (by which we mean
an unloaded part) ((and spare "bitter end" for meaning,
as per origin, "that part of the line at the bitts")).

So, loading a butterfly bend's tail vs. one normal S.Part
is a peculiarity beyond anything I meant to consider.
(The eye knot necessarily loads both such "tails"
--they are the eye-legs-- vs. one or the other S.Part;
this is a relation different from the commonly expected
relation between supposed cognate end-2-end & eye knots,
where one fully loaded S.Part of latter becomes a 50%
loaded eyeleg in conjunction w/one former tail.)

3) Your knots both look so tight of collars
that they will be prone to jam --in short, they
diminish that visual aspect of the knot as beheld
by discoverers (among others) Wright & Magowan
such that they gave the linemen's loop its more
popular (?) moniker "butterfly".
As for yours, it looks like you're trying to get
a jammed knot!

But complaints of jamming came to me via one
IGKT French sometime-caver as being rumored
in the caving community.  YMMV on exact circumstances.
(I've discovered alternatives, mostly which depend
upon one anticipating direction of loading --and this
is often known-- and tying a knot per such context.)

Quote
I will see if anyone in the crusing community with access to load testing equipment can test out the strength of the various ways the Alpine BB can be dressed. If so, I will report back.
What might be most to be gained from least
testing would be information about where
the break comes (and, if in laid rope, whether
1-2-or-3 strands all break (presuming that the
test device can arrest pull upon the rupture of
part of the line, which seems to be something
often done)) --via some clever marking of the
parts of the knot after some initial loading to
remove much stretch & movement from knot
compression.
  As particular figures of strength are less meaningful
per so many factors, but maybe point of rupture is
more informative?

--dl*
====
Title: Re: Are there 2 correct ways of dressing the Alpine Butterfly?
Post by: xarax on July 06, 2014, 10:00:20 PM
http://igkt.net/sm/index.php?topic=3811.msg22514#msg22514
Title: Re: Are there 2 correct ways of dressing the Alpine Butterfly?
Post by: Seaworthy on July 07, 2014, 05:06:31 AM
http://igkt.net/sm/index.php?topic=3811.msg22514#msg22514

Thanks for the link. It is not common knowledge in the sailing community that the AB loop is hard to untie after significant load has been applied. Having a play with it post jamming experience (when I was testing slippage of bends and using the AB loop to secure one end around the winch), it is apparent the load is just on one overhand. The dynamics of the knot alter completely when load is put on the loop.
Title: Re: Are there 2 correct ways of dressing the Alpine Butterfly?
Post by: Seaworthy on July 07, 2014, 05:19:32 AM
1) "never seen it presented this way" should be
put up in LARGE FONT as an emphasis NOT on
some sort of consensus but on the all-too-typical
parroting that cheapens (esp.?) knotting literature
--it can be amazing, and appalling (errors replicated, i.e.)!

Coming across this statement is disquieting too :(. The sailing community does not generally delve any deeper than standard texts/websites.

3) Your knots both look so tight of collars
that they will be prone to jam --in short, they
diminish that visual aspect of the knot as beheld
by discoverers (among others) Wright & Magowan
such that they gave the linemen's loop its more
popular (?) moniker "butterfly".

But complaints of jamming came to me via one
IGKT French sometime-caver as being rumored
in the caving community.  YMMV on exact circumstances.
(I've discovered alternatives, mostly which depend
upon one anticipating direction of loading --and this
is often known-- and tying a knot per such context.)

I have dressed the ABB as shown in the first 2 photos in post #1 with no jamming under the loads I have subjected it to. I have no experience with the second lot of dressing that I photographed.

Dan, I am still in the dark though. If neither if these dressing versions I show are "correct", then how did Wright & Magowan dress this bend? How do you dress it?

I can see that crossing the tails may make it stronger, but to me it does not appear that this would have much effect on the collars (and hence the jamming capacity).


Title: Re: Are there 2 correct ways of dressing the Alpine Butterfly?
Post by: Dan_Lehman on July 07, 2014, 09:10:56 PM
Quote
Thanks for the link.
+1 !   :)

Quote
It is not common knowledge in the sailing community that the
AB loop is hard to untie after significant load has been applied
Is it at all "common" for the sailing community to USE it?
(I've not seen it among my marine observations.)


Quote
I have dressed the ABB as shown in the first 2 photos
in post #1 with no jamming under the loads I have subjected it to.
How much load?  --in slippery new rope?

What is visible at the state you present is the surrounding
of SPart & opp. turn by the collar, which completely wraps
rope parts (and no *air*) --contrast w/that of a bowline
or zeppelin knot.  Now, from the state you show,
perhaps some draw by SPart on the collars pulls them
a bit back from this.  (There are ways to dress Ashley's bend
#1452
to have such jamming --or not.)

Quote
Dan, I am still in the dark though. If neither if these dressing
versions I show [is] "correct", then how did Wright & Magowan
dress this bend? How do you dress it?
... as in top, center, and botton-left, of my images.
The "pretzel" & "timber-hitch" forms of the interlocked
overhands both press upon their own tails without
an intermediary part.  (Now, the next question is Which
end do you load (or prefer to be loaded) for the eyeknot?

Hmmm, I'd need to play around with this.  The risk is
that the collar of the unloaded then-tail/alternative-SPart
will draw tight around that part --which, being unloaded,
won't hold the collar open.)


--dl*
====
Title: Re: Are there 2 correct ways of dressing the Alpine Butterfly?
Post by: [Inkanyezi] gone on July 08, 2014, 12:40:01 AM
Quote
It is not common knowledge in the sailing community that the
AB loop is hard to untie after significant load has been applied
Is it at all "common" for the sailing community to USE it?
(I've not seen it among my marine observations.)
Neither have I, and I have never used the AB bend for anything serious. I have played around with it, before deciding that as a bend, it has little to offer. It is a bit awkward to tie in larger stuff, and it has a tendency to jam. As my preferred bend, the Carrick Bend, is easier to tie and less prone to jamming (never had it jam), I have used it whenever a bend that I would have to trust would be tied.

The butterfly mid-line loop however is a knot that I have used extensively for my mooring lines for well over thirty years. They won't jam, as there are never any great forces on the moorings, and moreover, they will always stay in the same position on the lines, so there is no need to untie them. But I haven't yet seen anyone copy my way of mooring, even though it has advantages over mostly used ways. There are two lines from the winches to the jetty, and about midline, each one has a butterfly loop, to which another line is tied toward the prow. This way I don't need any mooring springs, as there are never any jerks on the mooring lines. This geometry is very easy on ropes and hardware, and I can sleep calmly in the boat even if there's considerable swell.

(http://ifokus-assets.se/b66e88be48f496b055902c34857500b8/shrink/660x800/uploads/7c2/7c23ae94f09c7869067f207feb3caddc/mooring.jpg)
Title: Re: Are there 2 correct ways of dressing the Butterfly?
Post by: roo on July 08, 2014, 01:50:57 AM
Quote
It is not common knowledge in the sailing community that the
AB loop is hard to untie after significant load has been applied
Is it at all "common" for the sailing community to USE it?
(I've not seen it among my marine observations.)
Neither have I, and I have never used the AB bend for anything serious. I have played around with it, before deciding that as a bend, it has little to offer. It is a bit awkward to tie in larger stuff, and it has a tendency to jam. As my preferred bend, the Carrick Bend, is easier to tie and less prone to jamming (never had it jam), I have used it whenever a bend that I would have to trust would be tied.

The butterfly mid-line loop however is a knot that I have used extensively for my mooring lines for well over thirty years. They won't jam, as there are never any great forces on the moorings, and moreover, they will always stay in the same position on the lines, so there is no need to untie them. ...


I've had the opposite experience.  While I've had the Butterfly Loop (http://notableknotindex.webs.com/butterflyloop.html) occasionally jam under extreme load, I've never been able to make the Butterfly Bend (http://notableknotindex.webs.com/butterflybend.html) jam no matter what I've done to it.  I don't really employ the bend form though, as I prefer the improved security found in the Zeppelin Bend.
Title: Re: Are there 2 correct ways of dressing the Butterfly?
Post by: [Inkanyezi] gone on July 08, 2014, 09:15:51 AM
I've had the opposite experience.  While I've had the Butterfly Loop (http://notableknotindex.webs.com/butterflyloop.html) occasionally jam under extreme load, I've never been able to make the Butterfly Bend (http://notableknotindex.webs.com/butterflybend.html) jam no matter what I've done to it.  I don't really employ the bend form though, as I prefer the improved security found in the Zeppelin Bend.
Horses for courses. Where I apply it, the lines are never even close to SWL. The force in my mooring lines can always be handled by hand power, which might approach about 250 N (25 kp). The reason is that they are never shock-loaded, as the geometry prevents jerks on the mooring. At such low load on 1/2 " polyester lines, the knot will not draw up till jamming. The boat sometimes, when someone is approaching the harbour carelessly, can pitch up and down almost a metre, and the geometry of the moorings keep it in place without restraining pitch.

Where there are Y-beams, I have used another approach that is similar. Then I have lines along the beams, with a butterfly loop at the correct position for the winches and no other attachment points than the winches. The eye is drawn around the winch one or two turns, under the rope and dropped over the winch.

A small boat will never exert any great power on its moorings, if jerks are prevented. The more common way of drawing lines directly from bow or stern to the jetty can generate jerks that cause wear and can tear cleats out of the deck.

(http://ifokus-assets.se/1101d9dbb6fdc4c996812f54e281b077/shrink/660x800/uploads/255/2556ea23422072857682cc49fedd9a21/bommar.jpg)
Title: Re: Are there 2 correct ways of dressing the Butterfly?
Post by: Seaworthy on July 08, 2014, 02:50:40 PM

.......Where there are Y-beams, I have used another approach that is similar. Then I have lines along the beams, with a butterfly loop at the correct position for the winches and no other attachment points than the winches. The eye is drawn around the winch one or two turns, under the rope and dropped over the winch.

A small boat will never exert any great power on its moorings, if jerks are prevented. The more common way of drawing lines directly from bow or stern to the jetty can generate jerks that cause wear and can tear cleats out of the deck.

(http://ifokus-assets.se/1101d9dbb6fdc4c996812f54e281b077/shrink/660x800/uploads/255/2556ea23422072857682cc49fedd9a21/bommar.jpg)

Sorry Ink, but this method is not very good :(.
All you have here are spring lines stopping the boat from moving backward and forward. What do you have to stop the boat from yawing? In this set up the bow or stern are free to yaw around and hit the pontoon.
Title: Re: Are there 2 correct ways of dressing the Alpine Butterfly?
Post by: Seaworthy on July 08, 2014, 03:06:54 PM
Quote
It is not common knowledge in the sailing community that the
AB loop is hard to untie after significant load has been applied
Is it at all "common" for the sailing community to USE it?
(I've not seen it among my marine observations.)

No, certainly not "common", but it is in use, both as a means of bypassing a section of damaged line when it is tied as a midline loop, or as a means of joining two ropes together when used as a bend. Currently for the latter I think the sheet bend or double sheet bend are sometimes in use, but I suspect when more security is required two bowlines are employed, simply because sailors are at a loss deciding what else to use. Information about the quartet of twin overhands is slowly filtering though the network.

Quote
I have dressed the ABB as shown in the first 2 photos
in post #1 with no jamming under the loads I have subjected it to.
How much load?  --in slippery new rope?

I have used non slippery old rope (unsheathed nylon or double braided polyester) under reasonably high load (sorry, can't specify how much, but probably loads at least half that required to snap the nylon line of the snubber in storm conditions). The collar looks tight when in fact in can very easily be moved to the loosened position shown in your versions. I have had no problem untying the bend afterwards. There has been no slippage despite the lack of crossing the tails as in the version your prefer.

Quote
Dan, I am still in the dark though. If neither if these dressing
versions I show [is] "correct", then how did Wright & Magowan
dress this bend? How do you dress it?
... as in top, center, and botton-left, of my images.
The "pretzel" & "timber-hitch" forms of the interlocked
overhands both press upon their own tails without
an intermediary part.  (Now, the next question is Which
end do you load (or prefer to be loaded) for the eyeknot?

Hmmm, I'd need to play around with this.  The risk is
that the collar of the unloaded then-tail/alternative-SPart
will draw tight around that part --which, being unloaded,
won't hold the collar open.)

OK, I think I finally have it "right". The collar needed to be looser and in the first image I presented in post #1 and I have given the tails a clockwise twist. Have I finally got it right?
Title: Re: Are there 2 correct ways of dressing the Butterfly?
Post by: [Inkanyezi] gone on July 08, 2014, 03:37:04 PM

.......Where there are Y-beams, I have used another approach that is similar. Then I have lines along the beams, with a butterfly loop at the correct position for the winches and no other attachment points than the winches. The eye is drawn around the winch one or two turns, under the rope and dropped over the winch.

A small boat will never exert any great power on its moorings, if jerks are prevented. The more common way of drawing lines directly from bow or stern to the jetty can generate jerks that cause wear and can tear cleats out of the deck.

(http://ifokus-assets.se/1101d9dbb6fdc4c996812f54e281b077/shrink/660x800/uploads/255/2556ea23422072857682cc49fedd9a21/bommar.jpg)

Sorry Ink, but this method is not very good :(.
All you have here are spring lines stopping the boat from moving backward and forward. What do you have to stop the boat from yawing? In this set up the bow or stern are free to yaw around and hit the pontoon.
I reccon you didn't try it then? There is no way the boat can jaw. It can move slightly sideways, a few inches, but it stays where it is. Opposing spring lines prevent jawing. The method is well tried as I said, well over thirty years. With the Y-beams, there is less yawing than when tied from a buoy, but also in the former case, jawing is no problem.

If it seems as the bow would be free to jaw, try to imagine a straight plank where the winches are attached instead of the boat, and see what kind of freedom it has to move. You can push that plank a bit toward any of the Y-beams, but you cannot get any end of the plank closer to or further from the jetty; you cannot twist it.

There simply is no power acting upon the boat to cause jaw. Any sideways power will act just about the same fore and aft, so a sideways drift will not jaw, but tends to move the whole boat sideways. When the lines are well stretched movement will be very small, only a few inches. Even if you deliberately force the prow to the side, the stern (and of course the rest of the boat) will move somewhat in the same direction.

People often overestimate the powers acting on a boat that is tied up, and at the same time don't bother a lot to analyse the geometry of the mooring lines. I agree, that for a large ship, this method might be infeasible and unnecessary, although for a small boat it is quite handy and evades one of the more common problem with moorings, that pitching will cause jerks in the lines attached at the jetty.

The only constant (or long lasting) forces acting upon the lines, not considering their initial tension, are those from wind and current. They are usually rather small. For my 23' boat of one and a half tonnes, they never become stronger than what can be countered by the puny power I can exert through my hands. Excessive powers however can be generated by swell combined with unsuitable geometry of the mooring lines. When tying up stern or prow to the jetty, pitch may cause jerks that exceed what the gear can take. I have seen fairleads ripped out, cleats too, and mooring lines broken, even when mooring springs were used to cope with the jerks.

There is also an alternative way to attach the spring lines, if you have an attachment point midships at the beams, when you can draw them to fore and aft cleats. Still just two attachment points, but now on the beams, with four points on the boat. It is perhaps easier to see then, that the starboard aft spring and the port fore spring will prevent jaw to starboard and vice versa. I have used this method when the beams were short and with a taller boat, so that the outer ends of the beams were about midships. Then springs from the prow to the end of the Y-beam as well as from stern holds it steady without jawing.

Just as with knots, testing will show whether it works or not.
Title: Re: Are there 2 correct ways of dressing the Butterfly?
Post by: Seaworthy on July 08, 2014, 09:36:29 PM
I reccon you didn't try it then? There is no way the boat can jaw. It can move slightly sideways, a few inches, but it stays where it is. Opposing spring lines prevent jawing. The method is well tried as I said, well over thirty years. With the Y-beams, there is less yawing than when tied from a buoy, but also in the former case, jawing is no problem.

If it seems as the bow would be free to jaw, try to imagine a straight plank where the winches are attached instead of the boat, and see what kind of freedom it has to move. You can push that plank a bit toward any of the Y-beams, but you cannot get any end of the plank closer to or further from the jetty; you cannot twist it.

No I haven't tried it. Not game :D.
The problem is that lines are not like planks, they have a significant amount of stretch and can compress. The lines can't (and shouldn't) be tied on so tightly that they are as taut as wire.

Just as with knots, testing will show whether it works or not.

Unfortunately, if this fails in could lead to substantial damage. Not something that can be safely tested out with high wind strengths when forces are definitely not "rather small". Maybe in a small vessel with negligible forces on the lines this may be adequate, but I would not like to use this system otherwise.
Title: Re: Are there 2 correct ways of dressing the Butterfly?
Post by: [Inkanyezi] gone on July 08, 2014, 09:44:03 PM
I reccon you didn't try it then? There is no way the boat can jaw. It can move slightly sideways, a few inches, but it stays where it is. Opposing spring lines prevent jawing. The method is well tried as I said, well over thirty years. With the Y-beams, there is less yawing than when tied from a buoy, but also in the former case, jawing is no problem.

If it seems as the bow would be free to jaw, try to imagine a straight plank where the winches are attached instead of the boat, and see what kind of freedom it has to move. You can push that plank a bit toward any of the Y-beams, but you cannot get any end of the plank closer to or further from the jetty; you cannot twist it.

No I haven't tried it. Not game :D.
The problem is that lines are not like planks, they have a significant amount of stretch and can compress. The lines can't (and shouldn't) be tied on so tightly that they are as taut as wire.

Just as with knots, testing will show whether it works or not.

Unfortunately, if this fails in could lead to substantial damage. Not something that can be safely tested out with high wind strengths when forces are definitely not "rather small". Maybe in a small vessel with negligible forces on the lines this may be adequate, but I would not like to use this system otherwise.

As stated, the ordinary way sometimes fails and has caused substantial damage, continuing to do so.

You may test it with a model, which is not as costly in case of a failure, but I find your way of responding here downright st*d. I have devised a way of tying the boat, which is substantially superior to the most common ways of doing it. I have tried it through about thirty years without failure, in storm as well, and I know that it is far better in exactly the respect that you say it will fail. I can back it up, and you refuse to back up your claim.

If you arrange the lines in a way that they cannot and will not cause any jerks, there is no reason to have any slack. In fact, this way of tying can be done with lines that are not resilient - you could do it with wire rope, rods, HMPE if you will, but ordinary polyester stuff used for sheets and halyards is what I have used mostly, for the simple reason that I got it free after someone else decided to change those halyard fibre rope tails when I worked in the riggery.

So, you might not be game, but please don't say it does not work when you haven't tried. That amounts to a lie.