International Guild of Knot Tyers Forum

General => Practical Knots => Topic started by: Seaworthy on June 17, 2014, 01:19:53 PM

Title: Important Double Sheet Bend query
Post by: Seaworthy on June 17, 2014, 01:19:53 PM
Hi
I have been a full time cruising sailor for the past six years, during which time I have developed a keen interest in knots.

I have several questions that I am hoping forum members here may be able to help me with.

My first question is regarding the humble Double Sheet Bend, a very useful knot for sailors, particularly when you need to quickly connect two non slippery lines of different diameter reasonably securely on board a boat (typically double braided polyester). I have posted my query on Cruisers Forum with some very helpful members chiming in and providing ABOK links and knot numbers, but no conclusive answers.

I am querying how this simple knot is best tied. I think it is possible that the current method that seems to be commonly taught is not the best one.

All diagrams I have come across show ABOK #1434 and give the description of tucking the tail under the first loop over (ie tying a single sheet bend first) before proceeding to loop the tail around the bight a second time and tucking it under again. See Grogs Animated knots if my explanation is not clear.

When tying any knot, I try and snug it down so it sets neatly and slippage is avoided. For years I have given the first turn of the standard Double Sheet Bend (ABOK #1434) a bit of a push to do this. I have assumed that when the knot is under load it would often slip into this position naturally anyway (wrong assumption by the way). If it did not, I think the knot would not grip as well.
What I end up with is ABOK #488.

Ashley called both of these a Double Sheet Bend.

At some point I started tying the DSB differently so that this push was not needed to get from #1434 to #488. I do not tie a single sheet bend first, instead I make the second turn away from the apex of the bight before bringing the tail under both turns.

The lines I used in the following photos were ordinary double braid polyester: 10 mm for the thinner and 16 mm for the thicker (our yankee sheet). They were older, slightly stiffer, salt impregnated lines, typically what sailors tie knots in. This may have affected results.

This is ABOK #1434, which is the current way taught of tying a Double Sheet Bend:
Title: Re: Important Double Sheet Bend query
Post by: Seaworthy on June 17, 2014, 01:21:08 PM
This is ABOK #488, the DSB version I tie:
Title: Re: Important Double Sheet Bend query
Post by: Seaworthy on June 17, 2014, 01:22:43 PM
I could only perform a highly unscientific trial (unknown variable force with few tests, please don't crucify me for my rough and ready methods) tightening up the knot by tying one end on a cleat and winching the other end, but my longstanding impressions about the 2 versions look to be possibly correct.

#1434 seems much worse, as in my trials there was always considerable slippage of both lines. I was hesitant to apply any more force to see if the slippage eventually stopped.

It was suggested on Cruisers Forum that the slippage was occurring as I had not tightened the knot before putting load on it. The problem was that with older salty stiffer line, the knot instantly loosened as I let go and a tight fit was not achievable.

This was the typical result for ABOK #1434:
Title: Re: Important Double Sheet Bend query
Post by: Seaworthy on June 17, 2014, 01:24:06 PM
For ABOK #488, the version I use, there was always no slippage of the thicker line and only tightening, not slippage of the thinner one:
Title: Re: Important Double Sheet Bend query
Post by: Seaworthy on June 17, 2014, 01:25:04 PM
Correct me if I am wrong, but to me it seems that a DSB is essentially just a double overhand around the bend. I would call ABOK #1434 a DSB where the double overhand that has been left completely "unsnugged" even if it is tightened up. ABOK #488 is a DSB with the knot correctly snugged.

All other double overhands I have ever come across (whether used on their own as in a stopper, or as part of other knots like the double fishermans) are ALWAYS snugged by rolling over the loops so that that nice ball forms. It was just instinctive to do this whenever I have tied my version of the DSB, as un-snugged knots have the disastrous potential of slipping. ABOK #1434 just never seemed finished to me.

However, the two knots are not the same in use. ABOK #1434 does not turn into ABOK #488 when load is put on it (at least it certainly didn't do so for my winch trials using the line specified earlier).

So my queries are:
- Is ABOK #488 actually better than ABOK #1434, as I have always thought?
- If so, why is ABOK #1434 taught as the correct way to tie a Double Sheet Bend?
- Just out of curiosity, when was ABOK #1434 adopted? Has it always been the knot of use for a DSB?

Also to confirm which version of the DSB is better (for lines of both equal and unequal diameters), is anyone able to do some stress load test for me please?
Title: Re: Important Double Sheet Bend query
Post by: Luca on June 17, 2014, 08:30:39 PM
Hello Seaworthy,

I am not able to answer your questions, but if you prefer to use the Double Sheet bend dressed as # 488, maybe you can try this "Tresse" version of the Sheet bend(with or without the final slipping):

http://igkt.net/sm/index.php?topic=4880.msg31884#msg31884

                                                                                                                    Bye!
Title: Re: Important Double Sheet Bend query
Post by: Dan_Lehman on June 18, 2014, 04:26:52 AM
For ABOK #488, the version I use, there was always no slippage of the thicker line and only tightening, not slippage of the thinner one:

Discard them both!
Try this similar knot, intead:
looking at #488, follow the path of the
thinner (hitching) line from the tail
through the knot --it reaches across the
bight (not through it),
turns around it fully,
then turns around again but is tucked through
the bight.
So, with this vision, tie $488 in reverse
(tails are SParts & vice versa --which keeps the
"same side" relationship (tail & tail, SPart & SPart)).
BUT on both turns around the bight, tuck the
working end (of thinner line, in your example)
through the bight (otherwise, you'll have a jamming
knot!).  You might even make another turn,
and the tail can be further tucked out through
its own initial turn around the bight.
(If the diameters are much different, this becomes
problematic to secure, as the large-roped bight will
see too much space for the small hitching line to
be nipped.)

Consider this an extension of the Lapp bend
which itself is the (same-side) SB reversed.

TO LOOSEN & UNTIE, one pulls the legs of the bight
apart, to draw in enough --not much, but enough--
hitching-line SPart to enable one to work loose the
whole thing.  As the thinner ("hitching") SPart is
held by its own turns pressing down upon it but it
is otherwise following a straight path, it should
be possible to forcibly pull it, as described above.
(Big ropes enduring big forces might require some
Big Help --some device.)

The benefit of this multiple Lapp bend is that it can
be made secure-when-slack, and has this forcible
loosening method.

Btw, one can find netting that uses either of these
sheet bend geometries, but the #488 one might
be the more common, and better working.


--dl*
====
Title: Re: Important Double Sheet Bend query
Post by: xarax on June 18, 2014, 04:39:37 AM
   I had patiently waited till dL pops out, because he is the one that should be advised on this matter : the TWO Sheet bends, and how they are related to the Lapp bend.
   Even without a f... picture, his previous post is very well written and informative - search for the "Lapp" word in the Forum, to find more comments on the same issue.
   For other asymmetric bends, see at :
   http://igkt.net/sm/index.php?topic=4116
   http://igkt.net/sm/index.php?topic=4692.0
   http://igkt.net/sm/index.php?topic=4890
Title: Re: Important Double Sheet Bend query
Post by: Seaworthy on June 18, 2014, 05:54:37 AM
For ABOK #488, the version I use, there was always no slippage of the thicker line and only tightening, not slippage of the thinner one:

Discard them both!
Try this similar knot, intead:
looking at #488, follow the path of the
thinner (hitching) line from the tail
through the knot --it reaches across the
bight (not through it),
turns around it fully,
then turns around again but is tucked through
the bight.
So, with this vision, tie $488 in reverse
(tails are SParts & vice versa --which keeps the
"same side" relationship (tail & tail, SPart & SPart)).
BUT on both turns around the bight, tuck the
working end (of thinner line, in your example)
through the bight (otherwise, you'll have a jamming
knot!).  You might even make another turn,
and the tail can be further tucked out through
its own initial turn around the bight.
(If the diameters are much different, this becomes
problematic to secure, as the large-roped bight will
see too much space for the small hitching line to
be nipped.)

Consider this an extension of the Lapp bend
which itself is the (same-side) SB reversed.

TO LOOSEN & UNTIE, one pulls the legs of the bight
apart, to draw in enough --not much, but enough--
hitching-line SPart to enable one to work loose the
whole thing.  As the thinner ("hitching") SPart is
held by its own turns pressing down upon it but it
is otherwise following a straight path, it should
be possible to forcibly pull it, as described above.
(Big ropes enduring big forces might require some
Big Help --some device.)

The benefit of this multiple Lapp bend is that it can
be made secure-when-slack, and has this forcible
loosening method.

Btw, one can find netting that uses either of these
sheet bend geometries, but the #488 one might
be the more common, and better working.


--dl*
====

Hi Dan
I find the way Ashley has drawn #488 about the most confusing knot I have ever seen LOL. I would say it wins the prize of "if I had to find the most intricate complicated way to show how 488 is tied, this is what I would do". Did he have a sadist streak?  :D

I will work through your explanation of the lapp bend later today, as it is not instantly apparent what you mean. Do you have a link to an image of it? I have searched for "lapp" here, but can't find an image. Don't worry if not, I will work it out (firstly I need to go and test the EStar and Bull Clove after breakfast).

I have been searching for a better knot than the double sheet bend for when lines are of different diameter, so the lapp may be very useful. Has anyone done load tests on it? And if so same diameter line or different? And what diameters? And what line?
All important for where the knot is of most use to sailors.

I generally tie an Alpine Butterfly Bend if I need to join two ropes of roughly the same size. In the last few days I have practiced the Zeppelin until I am super comfortable with it and will make that the knot of choice now. I was looking at the differences between the Alpine BB and Zeppelin yesterday and got all excited when I came up with the Hunter, until I discovered it was already a known knot :). It sounds like it would be a better option if there was no need for the lines to be untied afterwards.

But back to my original question now.

Sailors seem to be taught everywhere to tie the double sheet bend as per #1434, not #488. This may have gone on for decades, I have no access to books to see.

I believe #1434 is inherently weaker than #488, possibly particularly if the line diameters are different and the rope salty and a bit stiff.
Does anyone know if this is correct?
Has anyone done any load tests comparing 1434 and 488?

If 488 is better, then why has 1434 been adopted? :confused:

Title: Re: Important Double Sheet Bend query
Post by: Dan_Lehman on June 18, 2014, 07:06:42 AM
Hi Dan
I find the way Ashley has drawn #488 ...
WHOA, when I wrote "look at #488" I meant
for you to look at YOUR OWN PHOTO OF IT,
not Ashley's confused scribble (which might
be more accurate --a bit-- to what things look
like when fiddling the small material about which
he wrote, there --yarns).  (Ever notice how anglers
knots are seldom clearly shown --you see careful
tying steps, then instruction to "pull on tag end
while humming Jolly Roger" and ... the tied image
is just a squiggle : I really believe that most of the
illustrators/authors have no clue about what should
result!)

No, look at YOUR image/photo.  It should be clear.
What is tail/SPart/turn/tuck.  There is only so much
to work with; reversal is straightforward.

Quote
Has anyone done load tests on [Lapp bend]?
And if so same diameter line or different?
And what diameters? And what line?
All important for where the knot is of most use to sailors.
THINK about this : substitute "sheet" for "Lapp"!!
After centuries of use, has anyone reported testing
as you ask for this venerable knot,
noting sizes and which side --they're different-- breaks???!
(I know of none, including even myself, say, using
cheaply got mason-/fish-line.  .:.  lazy me!)

Quote
I generally tie an Alpine Butterfly Bend
if I need to join two ropes of roughly the same size.
In the last few days I have practiced the Zeppelin
until I am super comfortable with it and will make that
the knot of choice now.
And you'd use these *fashionable* knots instead
of Ashley's bend #1452 (or 1425!) because ... fad?

Quote
I was looking at the differences between the Alpine BB and Zeppelin yesterday and got all excited when I came up with the Hunter, until I discovered it was already a known knot :). It sounds like it would be a better option if there was no need for the lines to be untied afterwards.

SmitHunter's bend with the tails crossing
a bit differently makes a fine end-2-end knot,
too; and in many cases, even without.

Quote
Sailors seem to be taught everywhere to tie the double sheet bend as per #1434, not #488. This may have gone on for decades, I have no access to books to see.

I believe #1434 is inherently weaker than #488,
possibly particularly if the line diameters are different and the rope salty and a bit stiff.
Does anyone know if this is correct?
Has anyone done any load tests comparing 1434 and 488?

If 488 is better, then why has 1434 been adopted? :confused:
"better" : if it ain't broke, don't fix it.
"There are a hunnerd ways to tie that, and any
one is good as another" (paraphrase of one knotty
utterance by a waterman I recall reading).

Of what I see in commercial-fishing knotting,
most knots have their tails secured : hog rings,
tape, or tucked-through-lay.  I think that one can
see on Deadliest Catch imagery of the Alaskan crabbing
boats the pot warps tied to pot bridle eyes with triple
sheet bends
, in the tail-tucked-repeatedly form,
not one tuck under repeated wraps.

One further idea, re the sheet bend:
instead of tucking repeatedly, as you question,
make those not tuck but "overwraps" --i.e.,
take the end around OVER the SPart,
and only tuck the last one/two passes
(YMMV on needs per material & diameters).
.:.  The overwraps will bind the hitchin SPart
(like in an angler's blood knot / grapevine / snell),
but the final tucks should enable loosening,
by hand.  One might want to make one tuck
as normal, and the final sort of reversed,
by going OVER and tucking back-under,
to put X's "ugly" hard bend, which can defeat
loosening-back-into-knot movement, even if
the hitching SPart can feed back though the
thicker bight a bit.


--dl*
====
Title: Re: Important Double Sheet Bend query
Post by: Dan_Lehman on June 18, 2014, 07:09:31 AM
   I had patiently waited till dL pops out, because ...
Even without a f... picture,
Oh, but I DO have one --borrowed, and in
the post referred to, not repeated!   ::)

 ;)
Title: Re: Important Double Sheet Bend query
Post by: Seaworthy on June 18, 2014, 08:03:53 AM
Hi Dan
I find the way Ashley has drawn #488 ...
WHOA, when I wrote "look at #488" I meant
for you to look at YOUR OWN PHOTO OF IT,
not Ashley's confused scribble....

Phew, I would have needed a few stiff Scotches before working on Ashley's diagram of a 488 :D.
I will work on my own photo.

THINK about this : substitute "sheet" for "Lapp"!!
After centuries of use, has anyone reported testing
as you ask for this venerable knot,
noting sizes and which side --they're different-- breaks???!
(I know of none, including even myself, say, using
cheaply got mason-/fish-line.  .:.  lazy me!)

Well, I am not aware of load tests, but how these knots function best has certainly been passed down through the years. How much is anecdotal I don't know, but the old salts from years gone by were a canny lot and would have worked out pretty quickly what worked and what didn't.

For example, if the lines are of a significantly different diameter, sailors don't use a single sheet bend.

If lines are of a thick diameter, neither the sheet bend or double sheet bend are preferred, instead a Carrick is used.

With the new slippery lines, sailors are now at a complete loss :). Up to now I have used a triple fishermans. I know now there are better options and it would be great to find the best one.

I generally tie an Alpine Butterfly Bend
if I need to join two ropes of roughly the same size.
In the last few days I have practiced the Zeppelin
until I am super comfortable with it and will make that
the knot of choice now.

And you'd use these *fashionable* knots instead
of Ashley's bend #1452 (or 1425!) because ... fad?

Nope, because I have read that the Ashley and Hunter could not be untied after a load had been applied, so I never bothered even glancing at them. Sailors generally prefer to learn how to tie the minimum number of knots they can get away with :). I have never come across anyone using the Ashley bend on board a boat and simply dismissed it as an option.

Sailors seem to be taught everywhere to tie the double sheet bend as per #1434, not #488. This may have gone on for decades, I have no access to books to see.

I believe #1434 is inherently weaker than #488,
possibly particularly if the line diameters are different and the rope salty and a bit stiff.
Does anyone know if this is correct?
Has anyone done any load tests comparing 1434 and 488?

If 488 is better, then why has 1434 been adopted? :confused:

"better" : if it ain't broke, don't fix it.
"There are a hunnerd ways to tie that, and any
one is good as another" (paraphrase of one knotty
utterance by a waterman I recall reading).

Well, I have just found that it is "broke" LOL. I tested two braided polyester lines on my winch (16 and 10 mm) and 1434 simply slipped appallingly. 488 held with the roughly similar load I applied (showed zero tendency to slip on several pulls).

My concern is that 488 may have been the bend of choice by "salty old sailors" decades ago and that somehow when it came to putting it into textbooks on boating knots, someone got it wrong and this error has carried on for years (maybe because Ashley drew 1434 as a double sheet bend, putting 488 under weaver's knots instead).

There are not many "old salts" left. They don't look at text books and frankly don't care. They are probably teaching the knot correctly in practice, but most people are now learning from textbooks, classes or the internet and are therefore learning to tie the DSB the weaker way.

I have posed the question about this simple knot on a huge cruising forum (100,000 + members) and members seem extremely hesitant to admit what version of the DSB they are tying, or if they are tying it at all (one person had the courage to respond!!!!). I suspect they don't want to look foolish admitting they are tying knot a way that turns out to be the way that is prone to slipping :).

In lists members have put together of what they consider "vital" the DSB almost never makes an appearance now. I suspect these people would probably end up tying two bowlines when they need to tie lines of different diameter together.

Those using 1434 may find that at a time it is critical it will fail, with disastrous results.

So, my question remains.
Is 1434 or 488 going to perform better under load, particularly when the diameter of the lines is different?
If so, 1434 should be banished from sailors' repertoires :).
Title: Re: Important Double Sheet Bend query
Post by: asemery on June 18, 2014, 02:37:33 PM
When I make nets using nylon or other slippery twine I tie a double sheet bend thusly:

(http://i2.photobucket.com/albums/y18/asemery/modifieddoublesheetbend.jpg)

I have not tried this knot using heavier material.  Tony
Title: Re: Important Double Sheet Bend query
Post by: Seaworthy on June 18, 2014, 03:53:38 PM
Now I would like to pose an important question to the International Guild of Knot Tyers :).

I have just looked at your home page and checked out the Sea Cadet knots. Low and behold what do I find, you are displaying ABOK #1434 as the method of tying a Double Sheet Bend. I had to smile.

I have attached the photo from your web page below.

Why have you selected this knot in preference to the ABOK #488 version of the Double Sheet Bend?

I have not found #1434 to be nearly as secure using line of different diameter (eg 16 mm yankee sheet and 10 mm line both in double braid).
The DSB's prime purpose is to be used when lines are of different diameters.

Title: Re: Important Double Sheet Bend query
Post by: roo on June 18, 2014, 04:24:51 PM
Seaworthy,

If you're looking for a more secure bend, it's probably time to look toward a different bend rather than a different dressing of the double sheet bend (http://notableknotindex.webs.com/sheetbend.html).  If, for the sake of argument, your favored dressing is more secure, it's still not that great when compared to the continuum of other bends.  In mismatched line, a snag of the larger rope's free end may destroy the bend! And just to make sure the preferred dressing is made and maintained during tightening, you'll need expert and vigilant eyes.

It comes as a surprise to some, but the sheet bend family can become difficult to untie after hard strain.

For all these reasons, I would like to suggest the use of the Zeppelin Bend, which is more secure, stable, determinant in dressing, is more jam resistant, and better handles differences in line diameter:

http://notableknotindex.webs.com/Zeppelin.html
Title: Re: Important Double Sheet Bend query
Post by: Seaworthy on June 18, 2014, 05:15:06 PM
Seaworthy,

If you're looking for a more secure bend, it's probably time to look toward a different bend rather than a different dressing of the double sheet bend (http://notableknotindex.webs.com/sheetbend.html).  If, for the sake of argument, your favored dressing is more secure, it's still not that great when compared to the continuum of other bends.  In mismatched line, a snag of the larger rope's free end may destroy the bend! And just to make sure the preferred dressing is made and maintained during tightening, you'll need expert and vigilant eyes.

It comes as a surprise to some, but the sheet bend family can become difficult to untie after hard strain.

For all these reasons, I would like to suggest the use of the Zeppelin Bend, which is more secure, stable, determinant in dressing, is more jam resistant, and better handles differences in line diameter:


Roo that does not help LOL. The best alternative to a DSB is a totally separate issue. The DSB is still being taught and is still in use. Go have a look at the home page here. It is taught to Sea Cadets here.

The Zeppelin has been reported to be not good if the line is of quite different diameter. That is where the DSB is primarily used sailing. The Zeppelin is not a substitute.
Title: Re: Important Double Sheet Bend query
Post by: roo on June 18, 2014, 05:18:02 PM

The Zeppelin has been reported to be not good if the line is of quite different diameter.
It happens to be an incorrect report.  The Zeppelin Bend is far better with lines of different diameter than any member of the Sheet Bend family.
Title: Re: Important Double Sheet Bend query
Post by: Seaworthy on June 18, 2014, 06:07:34 PM

The Zeppelin has been reported to be not good if the line is of quite different diameter.
It happens to be an incorrect report.  The Zeppelin Bend is far better with lines of different diameter than any member of the Sheet Bend family.

Any evidence to support this? Who has tested and confirmed this and with what variations in diameter and what type of lines?
Title: Re: Important Double Sheet Bend query
Post by: roo on June 18, 2014, 07:25:21 PM

The Zeppelin has been reported to be not good if the line is of quite different diameter.
It happens to be an incorrect report.  The Zeppelin Bend is far better with lines of different diameter than any member of the Sheet Bend family.

Any evidence to support this? Who has tested and confirmed this and with what variations in diameter and what type of lines?
You should be able to do this yourself.  It's not a hard test.  Snagging the free end of the larger, U-shaped rope in sheet bend variants is a well-known weakness.

While this issue has been discussed at length in this forum in various places, there's nothing like having a first-hand experience.

ref:
http://igkt.net/sm/index.php?topic=1872.msg12785#msg12785
http://igkt.net/sm/index.php?topic=1872.msg12788#msg12788
Title: Re: Important Double Sheet Bend query
Post by: Dan_Lehman on June 18, 2014, 11:11:08 PM
THINK about this : substitute "sheet" for "Lapp"!!
After centuries of use, has anyone reported testing
as you ask for this venerable knot,
noting sizes and which side --they're different-- breaks???!
(I know of none, including even myself, say, using
cheaply got mason-/fish-line.  .:.  lazy me!)

Well, I am not aware of load tests, but how these knots function best has certainly been passed down through the years. How much is anecdotal I don't know, but the old salts from years gone by were a canny lot and would have worked out pretty quickly what worked and what didn't.
Perhaps, in some cases, and for some situations
(which might've changed, in time).  Whether the
popular literature captures this knot knowledge
is an entirely separate question --mostly, knot
books seem to copy other knot books, even errors!

Quote
For example, if the lines are of a significantly different diameter, sailors don't use a single sheet bend.

If lines are of a thick diameter, neither the sheet bend nor double sheet bend is preferred, instead a Carrick is used.
Really?
I've never found a carrick bend tied anywhere
in the Wild !  I've heard, well, seen on t.v., that
it is used by the Alaskan crabbers.  The zeppelin
would be good one for them, too, though they might
want to bind the tails (tape) and the former makes
that easier.

Quote
I generally tie an Alpine Butterfly Bend
if I need to join two ropes of roughly the same size.
In the last few days I have practiced the Zeppelin
until I am super comfortable with it and will make that
the knot of choice now.

And you'd use these *fashionable* knots instead
of Ashley's bend #1452 (or 1425!) because ... fad?

Nope, because I have read that the Ashley and Hunter
could not be untied after a load had been applied, so I never
bothered even glancing at them.  Sailors generally prefer to learn
how to tie the minimum number of knots they can get away with :).
I have never come across anyone using the Ashley bend on
board a boat and simply dismissed it as an option.
!!
Pity what misinformation can do --and that you
gave up so easily, rather than testing assertions
(which must've come from the Net).  #1452 can
be dressed to jam or not to jam; Ashley doesn't
illustrate the knot well, and might not have known
it so well, either.  You want to orient the tails so
that they start being rotated against each other
in a locking manner and are further so rotated by
the draw of the SParts.  (Unlike the butterfly bend,
#1452, #1408, & zeppelin have SParts rotating in
the same direction --the b.'s go opposite.)
(The jamming state might be beneficial when working,
e.g., with polypropylene rope in some light-load situation;
w/o heavy loading, you will easily be able to untie.)

Ashley's #1408 & the zeppelin have similar shapes
of their overhands, with the former interlocking
them more fully, but the latter giving more of a
sharp bend to the tail at its tuck, which I think
helps it resist *flowing* loose --material doesn't
move through the right-angle bend well, whereas
#1408 has a smoother bend here.

Quote
So, my question remains.
Is #1434 or #488 going to perform better under load,
particularly when the diameter of the lines is different?
If so, 1434 should be banished from sailors' repertoires :).
You shouldn't be so narrowly Index-to-exact-knot-minded,
but understanding of how the knots work so that
you can make adjustments per situation.
E.g., Roo warns of snagging of the bight-side tail
with the sheet bend-like knots : this vulnerability
can be redressed by essentially seizing the tail to
the SPart with the end of the hitching line,
using a multiple strangle knot (or, if you want
to keep to *fad*, a less-well-oriented vis-a-vis tails
alignment, constrictor  :P ); the first-formed
will do the heavy work, the seizing knot just will
keep things in place, and be no tighter than it
was set, roughly --and thus, loosenable.
[Here I'll remark at how "untiable" is an ambiguous
term --can we NOT tie it, or can we UN-tie it?!]

Frankly, the two previous knot alternatives I suggested
--those using overwraps of either hitching SPart and
one leg of the bight side, or both legs but then
with a more or less normal sheet bend front end,
will provide some *seizing-like* security vs. snagging.
(Of course, the zeppelin is woefully awkward with much
line-diameter difference, and will please only the most
pedantic & z.-zealous of mariners.   ;)  )

Btw, FYI Dave Richards of the Cordage Institute (or of
a member firm --but I believe he was on the board ...)
did testing of kernmantle ropes (rockclimbing, caving,
SAR), and found that sometimes the dbl.S.B. slipped
but not the single (& also the fisherman's knot(!),
sometimes both (resp. 12.5mm & 7mm low-elongation),
and once only the single (dynamic).  So, that was eye-opening!
(No photos to show details, et cetera, so much must be
presumed or left to question.)
((This report was taken off-line, sadly, for some minor
discrepancies --which should've been redressed quickly
and simply (and there were even offers to assist!)--,
and appears to be yet NA, unless maybe by something
called the Internet WayBack Machine or whatever ... !?))


--dl*
====
Title: Re: Important Double Sheet Bend query
Post by: xarax on June 18, 2014, 11:37:53 PM
mostly, knot books seem to copy other knot books, even errors !

Mostly, knot books ( and sites ) seem to mimic other knot books ( and sites ), in erring...
Title: Re: Important Double Sheet Bend query
Post by: roo on June 18, 2014, 11:38:51 PM
[...]
Of course, the zeppelin is woefully awkward with much
line-diameter difference, [...]
With much line diameter difference, any bend is going to look awkward.  Did you have some elegant exception in mind outside of a hitching solution?
Title: Re: Important Double Sheet Bend query
Post by: Luca on June 19, 2014, 12:11:36 AM
Hi Seaworthy,

For ABOK #488, the version I use, there was always no slippage of the thicker line and only tightening, not slippage of the thinner one:

Discard them both!
Try this similar knot, intead:
looking at #488, follow the path of the
thinner (hitching) line from the tail
through the knot --it reaches across the
bight (not through it),
turns around it fully,
then turns around again but is tucked through
the bight.
So, with this vision, tie $488 in reverse
(tails are SParts & vice versa --which keeps the
"same side" relationship (tail & tail, SPart & SPart)).
BUT on both turns around the bight, tuck the
working end (of thinner line, in your example)
through the bight (otherwise, you'll have a jamming
knot!). .......
I will work through your explanation of the lapp bend later today, as it is not instantly apparent what you mean. Do you have a link to an image of it?

(the "standard" Lapp knot: http://davidmdelaney.com/Lapp-knot/Lapp-knot.html )

I suspect that is something similar to the structure visible in the first image at the bottom of this post (to get the bend mantain the standing part in blue,cut the eye and use the second leg of the eye(in red) as the other standing part),but I expect to be disproved...

http://igkt.net/sm/index.php?topic=4321.msg27309#msg27309

As a bend it seems to be really good and secure, but do not use the loop version illustrated there if you do not want to risk of heavily imprecate while trying to untying it...(in fact even the bend can be a little difficult to untie, also for this I expect to be disproven ...)
(for the record,in the second diagram there,is illustrated that can be seen as a loop version of #488.The offer for try the "Tresse"(the term is by alpineer,which has presented the Tresse Bowline) version is still valid, the difference between the two is(apparently) minimal (continuation of the standing part over itself vs under it self).)
Regarding the Zeppelin topic, it may be interesting to this thread:

http://igkt.net/sm/index.php?topic=2159.msg15189#msg15189

                                                                                                                           Bye!


Title: Re: Important Double Sheet Bend query
Post by: Seaworthy on June 19, 2014, 03:51:09 PM
Dan, firstly, thank you for all the info. It has been very interesting reading your responses.
I will have a play with all 4 twin overhand bends.

If lines are of a thick diameter, neither the sheet bend nor double sheet bend is preferred, instead a Carrick is used.
Really?
I've never found a carrick bend tied anywhere
in the Wild !  I've heard, well, seen on t.v., that
it is used by the Alaskan crabbers.

It is still used for very thick line. Best bend for that, as far as I am aware.

So, my question remains.
Is #1434 or #488 going to perform better under load,
particularly when the diameter of the lines is different?
If so, 1434 should be banished from sailors' repertoires :).
You shouldn't be so narrowly Index-to-exact-knot-minded,
but understanding of how the knots work so that
you can make adjustments per situation.

Yes, agreed. But I am raising this issue because very few people using a DSB are at all aware there is a second version. So how can they make informed decisions?
If only one version is taught or displayed anywhere, why is it the worse one?

Btw, FYI Dave Richards of the Cordage Institute (or of
a member firm --but I believe he was on the board ...)
did testing of kernmantle ropes (rockclimbing, caving,
SAR), and found that sometimes the dbl.S.B. slipped but not the single

Ah huh! EXACTLY!!!

That is what I am jumping up and down about on this thread. I bet he ties #1434 (ducking for cover if not LOL), that all books teach, as does everything online and sailing school and even this website to Sea Cadets. #1434 can certainly slip in even double braided polyester. It is the un-snugged version of 488 and therefore not pre-tightened properly if it is only tightened and left in this form.

Maybe 1434 never slipped in natural fibres and so it was deemed adequate.

The big question I am raising in this thread is why is it taught exclusively now?

(& also the fisherman's knot(!),
sometimes both (resp. 12.5mm & 7mm low-elongation),
and once only the single (dynamic).  So, that was eye-opening!

Really fascinating stuff! Thank you. Such a pity the report was removed from view.
My theory is that these knots may have been inadequately pre-tightened or not snugged properly before load was applied.
Title: Re: Important Double Sheet Bend query
Post by: Seaworthy on June 19, 2014, 07:51:24 PM

Discard them both!
Try this similar knot, intead:
looking at #488, follow the path of the
thinner (hitching) line from the tail
through the knot --it reaches across the
bight (not through it),
turns around it fully,
then turns around again but is tucked through
the bight.
So, with this vision, tie $488 in reverse
(tails are SParts & vice versa --which keeps the
"same side" relationship (tail & tail, SPart & SPart)).
BUT on both turns around the bight, tuck the
working end (of thinner line, in your example)
through the bight (otherwise, you'll have a jamming
knot!).  You might even make another turn,
and the tail can be further tucked out through
its own initial turn around the bight.
(If the diameters are much different, this becomes
problematic to secure, as the large-roped bight will
see too much space for the small hitching line to
be nipped.)

Hi Dan
I have been looking at the lapp bend.
Could you please tell me if I have interpreted your instructions correctly?

The single I am reasonably confident with, the double not so:
Title: Re: Important Double Sheet Bend query
Post by: Seaworthy on June 20, 2014, 04:38:23 AM
Sorry, can see I stuffed up the double (wasn't paying attention).

The image I have attached below is simply the 488 with the standing part and tail reversed and with the tails still coming out on the same side.

The bit I am confused about is "BUT on both turns around the bight, tuck the working end through the bight (otherwise, you'll have a jamming knot!)."

Is a diagram or photo possible please or a link to one? Or now that I have this image any other way of explaining the tucks?

Title: Re: Important Double Sheet Bend query
Post by: Seaworthy on June 20, 2014, 04:43:42 AM
Oh, skip that LOL, the light just went on. I just had to tuck the end through the bight as you said :). Sorry, my brain just froze completely. I am not used to following knot instructions, but looking at images instead.

I will take a photo in a moment and post it.

I will give both a try on our winch later (making sure I don't use the end of my yankee sheet for the jamming version) and report back.
Title: Re: Important Double Sheet Bend query
Post by: Seaworthy on June 20, 2014, 05:06:18 AM
Now, if nothing else I am sure I am providing you with some entertainment :).

Take 3 of the double lapp is attached in the next post what I assume is its jamming form. When going to tuck the bight in I realised in take 2 I had not started the first pass over the top.

The tucked version will also be posted.

Anyone going to put me out of my misery and tell me if these are right before I test them? :)
Title: Re: Important Double Sheet Bend query
Post by: Seaworthy on June 20, 2014, 05:16:40 AM
Double lapp jamming and non jamming versions attached.
Before I go test it, is this finally correct?

If I just followed Dan's instructions it would have made it easier :).
Title: Re: Important Double Sheet Bend query
Post by: Seaworthy on June 20, 2014, 05:24:55 AM
Interestingly, did anyone notice that the first version I posted of the double lapp was in fact correct for the jamming version, just unsnugged?

ie It was based on the 1434 version of the DSB, not the 488. When finished, just rolling over the first turn in my first version produces the correct bend.
Title: Re: Important Double Sheet Bend query
Post by: Seaworthy on June 20, 2014, 06:50:10 AM
It is still too early in the morning to go test anything as the sheet winches are right above our cabin and my better half is asleep.

So, I have been playing with the single and double lapp bends in the same diameter line. I am extremely impressed. I will explain why I think these bends may be brilliant (they need proper load testing beyond my scope to check security, but I am very optimistic).

The big reason is that when pre-tightened up by hand as much as possible (so that the working tail ends up perpendicular to the two standing ends), when tension is put on the two standing ends everything just pulls together tighter. So when the tension is released, the knot is still snuggly set. On the other hand, the sheet bend, having had pressure put on to open up the apex of the bend slips a bit to set, and then has a big gap created in the apex, making it very easy to undo when the tension is released, but also making it extremely prone to coming undone on its own. Just holding a standing end and flapping it around a few times can undo the sheet bend.

Secondly, the lapp bend is quicker to tie than the sheet bend, as the tail never needs to be fed under any component, just through the bight, which is a much easier alternative. For those with clumsy or cold numb fingers, this is important.

Looking at it, I can see absolutely no drawbacks with it compared to the sheet bend, except perhaps that a bit more care may be needed to pre-tighten it so that the working tail ends up perpendicular ie it needs to be snugged well (only takes a couple of seconds, so no big deal). The sheet bend has no such problem as it naturally slips anyway when load is put on it.

So, if the above is correct, other than when you want to untie the bend very quickly after load has been applied, when would it be more appropriate using the sheet bend? Why is the lapp bend not currently commonly in use? No sailors I know have heard of this bend. Is seems better, so what is the catch? (Other than needing a diagram to learn how to tie it :))

PS You have successfully distracted me from the burning question on hand of why 1434 is presented as a DSB rather than 488. But my current question still stands :).
Title: Re: Important Double Sheet Bend query
Post by: Dan_Lehman on June 20, 2014, 06:56:35 AM
[...]
Of course, the zeppelin is woefully awkward with much
line-diameter difference, [...]
With much line diameter difference, any bend is going to look awkward.  Did you have some elegant exception in mind outside of a hitching solution?
"The sheet bend family" doesn't look so awkward,
and goes some way.  But, yes, it does really become
such a joining that one might prefer to see it as
hitching --indeed, I like to refer to a special
class of rope-2-ROPE joints as "bight hitches",
with the bigger rope pretty much playing an
*object* rather than doing much participation
in the *knotting*.  (It's a slippery slope, though,
as to what forms one might see as being such
"objects" being hitched to.  The bight (open or
closed --i.e., an eye) seems apt for the treatment.)

AND I think --w/o good knowledge-- that one
marine application would be messenger lines
--the hauling of ever larger lines by another
(of which I've read of breakage, so it mustn't
be entirely trivial!).


--dl*
====
Title: Re: Important Double Sheet Bend query
Post by: Dan_Lehman on June 20, 2014, 07:12:52 AM
Double lapp jamming and non jamming versions attached.
Before I go test it, is this finally correct?

If I just followed Dan's instructions it would have made it easier :).
Yep, reading "in slow motion" as it were would
be a help to many, here (who whine about photos)!   :D

And I might've noted the relation of #488 reversed,
though I was focused on the non-jamming version.
WHICH, incidentally, can --again-- be guarded against
that jamming : i.e., while the wrap-all wraps prevent
one from the forcible loosening method of pulling
apart the bight legs to prise in some hitching SPart,
one might build in resistance to jamming 'a la
sheet bend at the bight tip where the hitching
line enters (as I also suggested, above).

NB : I find it helpful to treat even eyes as though
they are "open" bights --i.e., a bight with one leg slack--,
as the focible loosening method just noted will work
best if the draw of the hitching SPart has pulled
that "slack" (tail, if "open" bight) leg a little over
the other leg, and reversing that movement in
forcibly untying I think gives one a little extra
movement (potential).

--dl*
====
Title: Re: Important Double Sheet Bend query
Post by: Seaworthy on June 20, 2014, 07:31:13 AM
Double lapp jamming and non jamming versions attached.
Before I go test it, is this finally correct?

If I just followed Dan's instructions it would have made it easier :).
Yep, reading "in slow motion" as it were would
be a help to many, here (who whine about photos)!   :D

Suitably chastised :).
Blame Grog for my inability to read instructions :).
Title: Re: Important Double Sheet Bend query
Post by: Seaworthy on June 20, 2014, 09:17:23 AM
I will move this discussion onto an old lapp thread. Any suggestions which one is most appropriate?

I have just trialled the jamming version on our sheet winches and results will be buried in this thread.
Will do non jamming version later. On the move shortly
Title: Re: Important Double Sheet Bend query
Post by: enhaut on June 20, 2014, 05:50:38 PM
Hi Seaworthy,
That was an interesting thread.
Maybe you already know Asher's Simple Simon Under.
Here it is ; a loose an a dressed version.
Are you able (time, interest) to test it with your gear?
I would love to know it's behavior vs the Double sheet bend. (slipping, jamming)
ths.
Title: Re: Important Double Sheet Bend query
Post by: Seaworthy on June 20, 2014, 08:06:00 PM
Hi Seaworthy,
That was an interesting thread.
Maybe you already know Asher's Simple Simon Under.
Here it is ; a loose an a dressed version.
Are you able (time, interest) to test it with your gear?
I would love to know it's behavior vs the Double sheet bend. (slipping, jamming)
ths.

Very happy to do that. My gear is very limited though, but a double sheet bend slips if tied as 1434 (16 & 10 mm double braid polyester was tested), so it has its uses.

I am using a 'Lewmar 55 two speed sheet winch' to winch the heavier line and tying a midline bowline on the other and looping it around an adjacent winch. I am winching by hand, maximum amount comfortably. It is not even vaguely near the breaking strength of the line. Wondering if I can put a load cell in the set up, or if more room between the winches is needed for this, but that would need to wait until I had a delivery address at the end of the year. I measured the amount of stretch in the line over 10 cm this morning using a ruler (gives a rough idea of relative load for each trial). I will make it 20 cm next time.

I had only had a chance today to do one quick trial on a double lapp jammable version. 5-10 trials of each would be good to make results more reliable. Slippage can just be measured with calipers by looking at tail length before and after the trial.

Before I set up proper trials I will have a carful read of Evans Starzinger's pdf to see exactly what test procedure he used. I also need to get hold of some new line (lots of old stuff only on board).

Anyway, I am not familiar with the Asher's Simple Simon Under, but will test it out with interest. Roughly what diameter line would you like tested? It is most likely it will perform differently for different sizes.


Title: Re: Important Double Sheet Bend query
Post by: enhaut on June 20, 2014, 09:13:48 PM
Quote
Roughly what diameter line would you like tested? It is most likely it will perform differently for different sizes.
The rope's ration  in my pictures is around 2/1.
Anyway pitch in anything you have at hand!
It's the slippage that is of interest for me.
Thanks
jr.
Ps Harry Asher also devised the Simple Simon Over and the Simple Simon Double.
Title: Re: Important Double Sheet Bend query
Post by: enhaut on June 20, 2014, 09:53:58 PM
Forgot the images ;D
Title: Re: Important Double Sheet Bend query
Post by: xarax on June 21, 2014, 12:33:12 AM
  5-10 trials of each would be good to make results more reliable.

  20 -25 results would be much better, IMHO. If you want to study their statistics, I recommend the Weibull distribution. Evans is a statistician, so he may help you on this, too.
Title: Re: Important Double Sheet Bend query
Post by: Seaworthy on June 21, 2014, 05:31:10 AM
  5-10 trials of each would be good to make results more reliable.

  20 -25 results would be much better, IMHO. If you want to study their statistics, I recommend the Weibull distribution. Evans is a statistician, so he may help you on this, too.

It is ages since I analysed anything statistically (30 odd years) so I am extremely rusty, but number of trials required also depends on spread of results. Any statisticians here able to lend me a hand? There is nothing commercial in any of this. I do not even have a blog, do not participate in Facebook, do not have a website. Results will be freely shared. I will report any conclusions on the cruising forum as well.

The problem on board is that apart from equipment, I am extremely limited by materials. I currently have old jib sheets and halyards I can use - precious as testing on old line is, I feel, vital. Old line has been stretched, UV exposed and salt impregnated. Unlike climbers who would replace line frequently after big loads, sailors continue using line for years. Tests in new line are great (and I will do these too), but unfortunately don't replicate 'real world' performance. Simply storing large quantities of line in different diameters is difficult.

The line (and particularly the knot) shouldn't be reused for trials as the trauma to the line may affect the subsequent result. Over a metre of line (x2) is used each time. So imagine how much line I am going to need if 25 trials are done per knot (per diameter, as thicker line performs very differently: the thicker the line, the bigger the gap when it bends). Just way beyond my scope.

I think perhaps all I can do is get a rough idea what knots look promising and need to be investigated further.
Title: Re: Important Double Sheet Bend query
Post by: xarax on June 21, 2014, 06:25:13 AM
  the number of trials required also depends on spread of results.

  And the  spread of the results depends on the number of trials !  :) The more tests you perform and the more results you acquire, the spread gets bigger. What will tell you the required size of sample you need , is the required reliability : of course, we do not need 5 sigma in knotting, as in Particle physics !   :) ( = one chance in two million, to be wrong ! )

Over a metre of line (x2) is used each time. So imagine how much line I am going to need if 25 trials are done per knot

Now you know one of the many reasons I prefer OPT !  :) ( Other People s Tests ).

thicker line performs very differently: the thicker the line, the bigger the gap when it bends).

   No, that is irrelevant : the relative geometry of all the elements of a knot does not change with size.
   What does not scale uniformly, is the size of the knot ( which changes ) in relation to the size of the individual fibres ( which remains the same ).

I think perhaps all I can do is get a rough idea what knots look promising and need to be investigated further.

  A "rough idea" is a much much much better thing than "no idea whatsoever" ( = the black box we were talking about the other day...). Go on !
Title: Re: Important Double Sheet Bend query
Post by: Seaworthy on June 21, 2014, 07:01:21 AM
thicker line performs very differently: the thicker the line, the bigger the gap when it bends).

   No, that is irrelevant : the relative geometry of all the elements of a knot does not change with size.
   What does not scale uniformly, is the size of the knot ( which changes ) in relation to the size of the individual fibres ( which remains the same ).

No, it is not irrelevant at all. It is critical. Wider diameter lines do not bend as easily, they become stiffer as the diameter increases. Imagine a 10 cm thick line. It can simply not be bent back well on itself - there is too much difference in the distance the outer part of the bend needs to travel compared to the inner (the inner portion can simply not compress enough to accommodate this). Let you mind go further and consider a metre wide line. How well will this bend? Then consider a thread. A very sharp turn is possible.

One unusual characteristic of unsheathed Dyneema is that it can be bent back at acute angles. Hugely in its favour. Imagine how much worse it would perform if this were not the case.

I think perhaps all I can do is get a rough idea what knots look promising and need to be investigated further.

  A "rough idea" is a much much much better thing than "no idea whatsoever" ( = the black box we were talking about the other day...). Go on !

Thanks for the encouragement. The work I do now will just be ground work. It will perhaps give me something interesting to work on when age or ill health make me a 'landsman' again.
Title: Re: Important Double Sheet Bend query
Post by: xarax on June 21, 2014, 07:39:51 AM
No, it is not irrelevant at all.

It is !  :)

Wider diameter lines do not bend as easily, they become stiffer as the diameter increases.

 "Stiffer", is a measure of the force you need to bend them. The wider the diameter, the bigger the size, the greater the force you need to apply, to bend a rope. I claim that, all other things remaining the same ( the braiding of the individual fibres, for example ), the size and the stiffness scale up uniformly. 

  Imagine a 10 cm thick line. It can simply not be bent back well on itself - there is too much difference in the distance the outer part of the bend needs to travel compared to the inner (the inner portion can simply not compress enough to accommodate this) .

  You are still talking about the force required to bend a rope. This force is relative to the size of the rope, of course. The difference in the length of the paths of the inner and outer threads scale up in exactly the same way as the size of the rope.

One unusual characteristic of unsheathed Dyneema is that it can be bent back at acute angles. Hugely in its favour. Imagine how much worse it would perform if this were not the case.

   Now you shift the goalpost again !  :) You mention a property of the material, not of the geometry...Dyneema does the same thing in small sizes and in large sizes, so the size of the line is irrelevant. I made a comment on your post, where you said that :

 
thicker line performs very differently: the thicker the line, the bigger the gap when it bends).

 

  Thanks for the encouragement. The work I do now will just be ground work. It will perhaps give me something interesting to work on when age or ill health make me a 'landsman' again.

   Actually, I believe that, on a boat, it may be easier to perform tests of knots than on land - where you have so many other much more seductive/important things to distract your attention and consume your time !  :) All you need is a long ram hydraulic bottle jack ( I do not think that the mechanical winches are suitable for strength tests...), your old lines, or old lines of other boats you will encounter in your journey, ( which may be weaker, but, if they are not worn locally, they will generally behave like just ropes of a smaller size...), and patience !  :)   
Title: Re: Important Double Sheet Bend query
Post by: Seaworthy on June 21, 2014, 07:50:15 AM
thicker line performs very differently: the thicker the line, the bigger the gap when it bends).

   No, that is irrelevant : the relative geometry of all the elements of a knot does not change with size.
   What does not scale uniformly, is the size of the knot ( which changes ) in relation to the size of the individual fibres ( which remains the same ).

Just coming back to this issue, I tested the single lapp bend using the same single line yesterday. I literally burst out laughing at the ease in which it slipped on the winch (I never imagined knot testing could be so funny)- it slipped like a hot knife through butter. I think has I tested this in thin line (still keeping the same ratio of 10:16 for the line diameter) the results would have been very different.
Title: Re: Important Double Sheet Bend query
Post by: Seaworthy on June 21, 2014, 08:08:16 AM
thicker line performs very differently: the thicker the line, the bigger the gap when it bends).

    No, that is irrelevant : the relative geometry of all the elements of a knot does not change with size.

No, it is not irrelevant at all.

It is !  :)

Well, let us agree to disagree then.

  Thanks for the encouragement. The work I do now will just be ground work. It will perhaps give me something interesting to work on when age or ill health make me a 'landsman' again.

   Actually, I believe that, on a boat, it may be easier to perform tests of knots than on land - where you have so many other much more seductive/important things to distract your attention and consume your time !  :) All you need is a long ram hydraulic bottle jack ( I do not think that the mechanical winches are suitable for strength tests...), your old lines, or old lines of other boats you will encounter in your journey, ( which may be weaker, but, if they are not worn locally, they will generally behave like just ropes of a smaller size...), and patience !  :)   

And how exactly would I secure a hydraulic jack? Or have the power to run it? Decks are aluminium. Winches are reinforced with extra aluminium underneath. And how well would a hydraulic jack survive in a wet salty environment, where decks regularly have salt water streaming over them? And if it was dismantled after each test, where would I secure this heavy item safely so that it wasn't a flying object the next time I hit bad weather? I live in a space that is probably not much bigger than most people's kitchens :).
Title: Re: Important Double Sheet Bend query
Post by: xarax on June 21, 2014, 08:30:10 AM
  I think has I tested this in thin line (still keeping the same ratio of 10:16 for the line diameter) the results would have been very different.

  Why ? If the material and the construction of the ropes were the same, the geometry does not change ( apart from the metric properties, which scale up or down ), so the results would have been the same.
  However, this may not happen, because, as the size of the rope increases, usually the pattern of the braiding of the rope in the core and at the sheath changes ( so, the strength of the core and the and the friction at the surface of the sheath changes ), and the very composition of the materials used for the rope ( the ratios between the quantities of the usually more-than-one kinds of fibres, for example ) changes, too - for various reasons, which we can only speculate : rope construction is a black art and a classified science !  :) So, it is a wise thing, indeed, to do the tests of knots directly on knots tied on ropes of the most common sizes, in the most critical applications ( as rescue and climbing, for example ). Otherwise, the extrapolation of the results of tests on knots tied on ropes of smaller sizes to knots tied on ropes of bigger sizes would be debatable, indeed. 
Title: Re: Important Double Sheet Bend query
Post by: xarax on June 21, 2014, 08:42:08 AM
And how exactly would I secure a hydraulic jack? Or have the power to run it?

   You do not have to "secure" it somewhere ! :)
A hydraulic bottle ( forget the "jack" word, which conveys the impression that it should be placed vertically, on a floor ), can be "free floating" : you can just wrap the rope around it, so the forces would be compressible, and would be applied only on the body of the jack, not on the boat. You will only need to attach two pulleys in each of its two ends, of a diameter that will allow the rope ( and the bend on it ) to turn around, without contacting the cylinder.
   With hydraulic jacks, you do not need "power" - just a manual pump, which, along with a good breakfast, can offer you all the power you will need !  :)
Title: Re: Important Double Sheet Bend query
Post by: [Inkanyezi] gone on June 25, 2014, 09:30:10 AM
I used this way to test some HMPE slings I had made, just wrapping them over the jack. None of them broke, neither did they slip, and when I struck them with a metal object they gave a high-pitched "ping" telling me, that the tension was indeed very high.

The jack i used had a safety valve, so that at about 3.5 "tonnes" the fluid recirculated.

I was unable to break polyester or polyamide this way, as it elongated under tension more than the jack could move. However I succeeded in jamming a few knots severely.

Back to the subject of the sheet bends, I too have found that properly used, the single is often less prone to fail than the double. However, for a long time I haven't used any of them, as very seldom a bend is needed, and at those occasions, the Carrick Bend is faster to tie, more secure, and easier to open after heavy load. This is also the main reason why I wouldn't use the Zeppelin Bend, as it is not so swiftly tied. It is however amply secure. So my solution was an alternative, not trying to improve the sheet bends. Otoh, as a becket hitch, I use any of them, single or double, depending on thickness difference.

One important advantage of the Carrick Bend is that it is as easily tied in ropes of large diameter, and that it needs not, or rather should not, be worked tight. It takes the correct form inevitably under load if left to its own devices. So any "proper dressing" can just be forgotten. It does dress properly all by itself. A boon is that it never jams.

I use my own method of tying the Carrick Bend, reminiscent of the Weaver's method of tying the Sheet Bend:
http://web.comhem.se/~u77479609/Carrick_Bend.pdf

http://www.youtube.com/watch?v=wTmwqYQI93Y

Like any choreography, it takes a bit of training to get the movements into the memory of the muscles, but once learned, just like cycling or swimming, it isn't forgotten.
Title: Re: Important Double Sheet Bend query
Post by: xarax on June 25, 2014, 11:20:38 AM
   All you need is a long ram hydraulic bottle ...

   If a single-stage hydraulic cylinder is not long enough ( nylon, for example, is a very stretchy material, and some more complex knots may consume some unpredictable amount of ropelength before they reach their final, most compact forms ), one may use a two- or even a multi-stage telescopic cylinder. Due to their construction ( extended areas of contact between the pistons, more seals, etc ), such cylinders are not so robust as the single-stage ones. However, even taking into account that the force required to break a, say, 1/2 inch line of the sling wrapped around the two pulleys is more than twice the MBS of the single line ( the mechanical advantage of such a simple machine works now as a dis-advantage, and the pulleys themselves, as Evans had noticed, by their friction, "protect" the line a little bit ), it is still well within the range a quite cheap telescopic hydraulic cylinder may reach.
   Now, if one wishes to dispense with such a telescopic cylinder able to deliver twice the MBS of the rope, he may use a less powerful, smaller pull-back ram cylinder instead - but then he will need two firm anchor points to attach the one end of this cylinder and the one end of the rope. On board of a small sailing ship, he will have to use an anchor s really looong shank ( cruising ships do not carry such long anchors nowadays ...), the boom ( and, perhaps, the boom vang itself, if it is strong enough, attached along the boom ), the lower part of a keel-stepped mast, or the reinforced part of bilge near the keel for this. I would nt submit any other part of the ship s structure ( the deck, for example...) to such heavy, repeated loadings.     
Title: Re: Important Double Sheet Bend query
Post by: Seaworthy on June 25, 2014, 02:11:41 PM
   All you need is a long ram hydraulic bottle ...

   If a single-stage hydraulic cylinder is not long enough ( nylon, for example, is a very stretchy material, and some more complex knots may consume some unpredictable amount of ropelength before they reach their final, most compact forms ), one may use a two- or even a multi-stage telescopic cylinder. Due to their construction ( extended areas of contact between the pistons, more seals, etc ), such cylinders are not so robust as the single-stage ones. However, even taking into account that the force required to break a, say, 1/2 inch line of the sling wrapped around the two pulleys is more than twice the MBS of the single line ( the mechanical advantage of such a simple machine works now as a dis-advantage, and the pulleys themselves, as Evans had noticed, by their friction, "protect" the line a little bit ), it is still well within the range a quite cheap telescopic hydraulic cylinder may reach.
   Now, if one wishes to dispense with such a telescopic cylinder able to deliver twice the MBS of the rope, he may use a less powerful, smaller pull-back ram cylinder instead - but then he will need two firm anchor points to attach the one end of this cylinder and the one end of the rope. On board of a small sailing ship, he will have to use an anchor s really looong shank ( cruising ships do not carry such long anchors nowadays ...), the boom ( and, perhaps, the boom vang itself, if it is strong enough, attached along the boom ), the lower part of a keel-stepped mast, or the reinforced part of bilge near the keel for this. I would nt submit any other part of the ship s structure ( the deck, for example...) to such heavy, repeated loadings.   

Xarax, thanks for putting thought into your suggestions, but they are totally impractical for a yacht on the water. Even at anchor, swell can rock a boat from side to side violently. If another vessel passes and the wake hits beam on (even tankers or cruise ships in the far distance), unsecured objects can go flying unexpectedly.

Some of the points you suggest for securing the line during testing would be pitifully inadequate, and for other more secure points I doubt if any boat owner would be willing to deliberately subject them to loads like this.

By the way, I can't imagine how you could use secure an anchor adequately to use its shank (and what would be holding you stationary if it was up on board and not on the seabed :)), and I'm not sure what you mean by cruising ships not carrying anchors with long shanks - ours is nearly a metre long :).

But your suggestions may be useful for anyone contemplating setting up some kind of system at home.

Performance is king when it comes to practical knots. Factors such as time taken tying, ability to do this single handed or in the dark and ability to undo the knot after load has been applied may be important, but holding ability is often paramount when it comes to assessing performance.

Load tests are really the only way of assessing this.
Title: Re: Important Double Sheet Bend query
Post by: Seaworthy on June 25, 2014, 02:20:50 PM
Back to the subject of the sheet bends, I too have found that properly used, the single is often less prone to fail than the double.

I have heard this several times now. May I ask how you tie the double (#1434 or #488)?

However, for a long time I haven't used any of them, as very seldom a bend is needed, and at those occasions, the Carrick Bend is faster to tie, more secure, and easier to open after heavy load. This is also the main reason why I wouldn't use the Zeppelin Bend, as it is not so swiftly tied. It is however amply secure. So my solution was an alternative, not trying to improve the sheet bends. Otoh, as a becket hitch, I use any of them, single or double, depending on thickness difference.

One important advantage of the Carrick Bend is that it is as easily tied in ropes of large diameter, and that it needs not, or rather should not, be worked tight. It takes the correct form inevitably under load if left to its own devices. So any "proper dressing" can just be forgotten. It does dress properly all by itself. A boon is that it never jams.
........
Like any choreography, it takes a bit of training to get the movements into the memory of the muscles, but once learned, just like cycling or swimming, it isn't forgotten.

Have you used the Carrick and Zeppelin for lines of different diameter? I haven't been game.

Yes, I agree the Carrick goes into muscle memory easily.
Title: Re: Important Double Sheet Bend query
Post by: xarax on June 25, 2014, 03:11:32 PM
   I doubt if any boat owner would be willing to deliberately subject them to loads like this.

   Which points do you mean ? Those I mentioned are adequately strong, in any boat large enough for a couple to live in, I guess. I was replying on you comment about the "aluminium deck". You do not have to attach your test rig on the deck at all.

... cruising ships not carrying anchors with long shanks - ours is nearly a metre long :) .

   It depends on what do you mean by "cruising ships". You had described a boat with a living space "smaller than a kitchen", and that made me imagine a small boat, not a large kitchen !  :) :) :)
   So, you live on a big enough boat ( larger than 60-65 ft LOA, I suppose ? ), on board of which I am pretty sure you can secure a simple ad hoc test rig like the one I suggest - even with some difficulty. You can possibly use this or any other long and strong enough shank as part of this rig, indeed, and attach the line at its one end and the body of a short pull-back cylinder on the other. Or attach your cylinder along the boom, or along the lower part of the mast. On such a boat, the boom and the mast will not suffer from the loads we are talking about - they are designed to withstand much greater strains. ( I used to sail on a Sun Odyssey 52 ft boat, so I do have some idea of the dimensions and the allowable loads of those parts I suggested you attach your test rig on ). Anyway, to prove that you are worth your salt, and truly "seaworthy", find a way to perform load tests of ropes and knots on board of your boat - it would be an interesting challenge per se !  :) 
Title: Re: Important Double Sheet Bend query
Post by: Dan_Lehman on June 26, 2014, 03:43:37 PM
Wider diameter lines do not bend as easily, they become stiffer as the diameter increases.

 "Stiffer", is a measure of the force you need to bend them. The wider the diameter, the bigger the size, the greater the force you need to apply, to bend a rope. I claim that, all other things remaining the same ( the braiding of the individual fibres, for example ), the size and the stiffness scale up uniformly. 
...

I stand uneasily on both sides of this debate!  :-\   :-\

On the one hand, the argument(s) that X. advances
seems perfectly understandable.  OTOH, I have SEEN
the odd cases --frequently, at one site (trawlers)--
of capsized bowlines in mooring lines, and yet that
knot elsewhere, in other lines much thinner, doesn't
do this (or do it so seemingly readily)?!?  And whereas
I had thought to explain this by Seaworthy's assertion
of greater stiffness in the larger ropes, in fact most of
those ropes seem surprisingly suppler --more so, e.g.,
than low-elongation caving ropes (e.g., BlueWater II)
and rockclimbing ropes.  (We can note that Mark Gomers's
article on bowlines shows a BW II knot that has gone
some way torwards capsizing, but still hasn't.)

So, I think that this is a puzzling question.
(As for HMPE's flexibility (at least in some forms),
that I think partly aids its slipping.)


--dl*
====
Title: Re: Important Double Sheet Bend query
Post by: [Inkanyezi] gone on June 26, 2014, 05:49:33 PM
Back to the subject of the sheet bends, I too have found that properly used, the single is often less prone to fail than the double.

I have heard this several times now. May I ask how you tie the double (#1434 or #488)?

Always 1434.

I think the spilling problems arise from the different diameters of the lines, that the single is never used for such large differences as the double sheet bend.

However, for a long time I haven't used any of them, as very seldom a bend is needed, and at those occasions, the Carrick Bend is faster to tie, more secure, and easier to open after heavy load. This is also the main reason why I wouldn't use the Zeppelin Bend, as it is not so swiftly tied. It is however amply secure. So my solution was an alternative, not trying to improve the sheet bends. Otoh, as a becket hitch, I use any of them, single or double, depending on thickness difference.

One important advantage of the Carrick Bend is that it is as easily tied in ropes of large diameter, and that it needs not, or rather should not, be worked tight. It takes the correct form inevitably under load if left to its own devices. So any "proper dressing" can just be forgotten. It does dress properly all by itself. A boon is that it never jams.
........
Like any choreography, it takes a bit of training to get the movements into the memory of the muscles, but once learned, just like cycling or swimming, it isn't forgotten.

Have you used the Carrick and Zeppelin for lines of different diameter? I haven't been game.

Yes, I agree the Carrick goes into muscle memory easily.

I have done security trials with both the Carrick Bend and the Zeppelin with different diameters, to see whether they can be used for such bending, and the Carrick Bend works well when the difference is not very large. So for two lines of say 3/4" and 1/2" a Carrick bend is secure, while it cannot be trusted for joining a 5 mm line to a 12 mm line. The Zeppelin is quite another thing. To join different diameters, just an extra turn with the smaller line makes it secure.

There is an earlier thread on this topic: The asymmetric Zeppelin Bend (http://igkt.net/sm/index.php?topic=2159.msg15189#msg15189)

In fact, it can even be used for a ridiculous difference in sizes between the ropes, as can be seen in post #13 in that thread.

(http://igkt.net/sm/index.php?action=dlattach;topic=2159.0;attach=2280;image)
Title: Re: Important Double Sheet Bend query
Post by: Seaworthy on June 27, 2014, 07:23:04 PM
Back to the subject of the sheet bends, I too have found that properly used, the single is often less prone to fail than the double.

I have heard this several times now. May I ask how you tie the double (#1434 or #488)?

Always 1434. 

If you are ever playing again with securing lines of different diameter could I get you to try #488 that I have always used? I have only recently become aware that #488 will not tighten into #1434, as I had always assumed it would want to. From test results I have performed #488 does seem to slip considerably less (not always indicative of the final strength of a knot, but it is a good start).


I have done security trials with both the Carrick Bend and the Zeppelin with different diameters, to see whether they can be used for such bending, and the Carrick Bend works well when the difference is not very large. So for two lines of say 3/4" and 1/2" a Carrick bend is secure, while it cannot be trusted for joining a 5 mm line to a 12 mm line. The Zeppelin is quite another thing. To join different diameters, just an extra turn with the smaller line makes it secure. It is such a simple knot and so easy to tie, that it must have its uses. I would hazzard a guess and say the vast majority of sailors are unfamiliar with the Zeppelin, using a sheet bend instead and it would be good to spread the word regarding the best way to tie this.

There is an earlier thread on this topic: The asymmetric Zeppelin Bend (http://igkt.net/sm/index.php?topic=2159.msg15189#msg15189)

I think I have a good contender then for tying lines of significantly different diameter. The Zeppelin with an extra final turn seems to be cropping up again and again as an option. This is really where I (and probably thousands of other sailors) flounder when tying lines. I think none of us feel confident with the double sheet bend for this purpose, although it is a great quick option when similar lines are being joined.

PS Good photo!
Title: Re: Important Double Sheet Bend query
Post by: Twine on October 04, 2014, 04:40:26 PM
Hi Seaworthy!
You ask if maybe the old salts had some preference as to which of the double sheet bends they prefer. I think they did, and they seem to agree with your opinion. I looked it up in Sam Svensson's "Handbok i sj?mansarbete" (title means handbook of sailor's work) where he puts the two double sheetbends in pictures next to each other for easy comparison, and Svensson says that ABOK #488 (the one made with one roundturn followed by one turn tucked under) is superior to ABOK #1434 (the one with both turns tucked under) for the following reasons: It is easier to tie it; it is is not as bulky (it is more elegant); it cannot jam; and it is always easy to untie. However, Sam Svensson says, the ABOK 1434 is preferable when the difference in size is very large; then you can make more turns (3-5) of the thinner line around the thicker bight (here he apparently means turns that are tucked under the incoming standing part; I like to think of them as "tucks", even if thay involve roundturns as well). Svensson doesn't discuss how secure they are, so I guess they both hold well enough in hemp or manilla. Svensson does not refer to ABOK numbers, but I added them above, for clarity.

These two knots are, as you have noticed, so different that it is impossible to transform one into the other by any kind of rearrangement or "dressing" of the parts inside the knot without untying it first. They should have different names since they really are different knots. Maybe #488 could be called "singly-tucked double sheetbend" and the other "twice-tucked double sheetbend" or something along those lines. In that way, when someone talks about the double sheetbend, we can ask them to specify if they mean the single-tucked or twice-tucked double sheetbend.
Title: Re: Important Double Sheet Bend query
Post by: xarax on October 04, 2014, 05:02:08 PM
  They should have different names since they really are different knots.

  I think that I agree - but then, by the same token, should the 2 pairs of the different "Eskimo" bowlines have different names ?   
Title: Re: Important Double Sheet Bend query
Post by: Twine on October 04, 2014, 05:13:39 PM
I don't know. What are Eskimo bowlines?
Title: Re: Important Double Sheet Bend query
Post by: xarax on October 04, 2014, 05:50:50 PM
   There are 4 variations of what most people call  " the Eskimo bowline ", which are, more or less, functionally ( as rope mechanisms ), geometrically and topologically different from each other.   
     http://igkt.net/sm/index.php?topic=3233.msg23797#msg23797
     http://igkt.net/sm/index.php?topic=5015.msg33060#msg33060
Title: Re: Important Double Sheet Bend query
Post by: Twine on October 04, 2014, 07:02:45 PM
I kept my reply short because it was off-topic. No offence meant and none taken. I've studied the pictures you provided of the Eskimo bowlines, and to me it seems to be AT LEAST two different knots going under the same name. I'll think about it a bit more, perhaps take some pictures, and when/if I think I have a good answer, I'll post a reply in the thread
"Re: What defines a Bowline? - structure, characteristics, topology"

Happy knotting!
Title: Re: Important Double Sheet Bend query
Post by: xarax on October 04, 2014, 08:31:20 PM
   Thanks.
   I believe that the left- and the right-hand "Eskimo" bowlines are less "similar" than the "corresponding" left- and right-hand common/standard bowlines. Also, the position of the Tail End ( which is the second leg of the collar around the eye leg of the Standing Part ) "over" or "under" the continuation of the returning eye leg, plays a major role - among other things ( re. slippage or stability ), it alters the topology of the knot.
   ( I have cited two posts where the "Eskimo" bowlines were seen to have some relation, via the corresponding Sheet bend bowline, to the Sheet bend(s), so the discussion was not completely off-topic... :))
   One has to weight all those things, as well as the way each knot is tied-in-the-end, to decide on the issue of the names. Personally, I have not made up my mind yet - but perhaps this is due to the lack of interest, and the absence of arguments on the issue ( despite my repeated efforts to stir a discussion ).   
   
Title: Re: Important Double Sheet Bend query
Post by: Luca on October 04, 2014, 09:15:01 PM
Hello Twine,

These two knots are..  ..so different that it is impossible to transform one into the other by any kind of rearrangement or "dressing" of the parts inside the knot without untying it first. They should have different names since they really are different knots.

#488 and #1434 are different knots because of their geometry,but topologically they are the same knot,ie they can be arranged in the one or the other form without anything to untie.Another form,similar to #488 but topologically different is illustrated here(is a slipped version): http://igkt.net/sm/index.php?topic=4880.msg31884#msg31884

                                                                                                                            Bye!


Title: Re: Important Double Sheet Bend query
Post by: Twine on October 04, 2014, 11:02:20 PM
If you can do that, please show me how.
Edit: Oh, never mind. No need to bother you with that, since after some study I see from Seaworthy's pictures that the knots #488 and #1434 really are identical. I thought that what Seaworthy was talking about was the variant of a double sheetbend which Svensson mentions, which really is topologically different. Turns out Ashley mentioned it too, and he gives it number 1435.

So, please pretend that I was talking about the difference between #1434 and #1435 all along, because that's what I (foolishly) THOUGHT I was talking about. Possibly because Sam Svensson thought it worth mentioning in his book. #1435 is #1434 with one tuck less, as Ashley says.

Anyway, to make everything perfectly clear, at least in my mind, ABOK#1434 is a twice-tucked double sheetbend, while ABOK #1435 is a single-tucked double sheetbend, that both Ashley and Svensson say are quicker to make than the twice-tucked one. Svensson also says the single-tucked one easier to untie, doesn't jam and is less bulky. It seems to me that it resists slip better as well.

Sorry about my misunderstanding.

Twine

PS The picture you linked to is a slipped version of ABOK #1435, and if it wasn't slipped, it would be a perfect picture of the knot I thought we were talking about all along.
Title: Re: Important Double Sheet Bend query
Post by: Luca on October 05, 2014, 12:07:56 AM
Take the "turn" (invisible, in the "back view" of the draw by Ashley (below)) corresponding to the portions of rope that I've marked in red, and take it over the (half invisible) "turn" corresponding to the portions of rope that I've marked in green;dress and set.Ashley himself says:"It is the same knot as the Double Sheet Bend(# 1434).Frequently it will pull up into the form here illustrated,which is equally secure.".
P.S:I saw your EDIT, but it can be useful for other users ( and..I was about to post when I saw it!)
(http://)

Title: Re: Important Double Sheet Bend query
Post by: Luca on October 05, 2014, 12:21:14 AM
Turns out Ashley mentioned it too, and he gives it number 1435.

Thank you, I have to confess that I had never realized that Ashley had also cataloged this version!

Title: Re: Important Double Sheet Bend query
Post by: Twine on October 05, 2014, 02:03:59 AM
Take the "turn" (invisible, in the "back view" of the draw by Ashley (below)) corresponding to the portions of rope that I've marked in red, and take it over the (half invisible) "turn" corresponding to the portions of rope that I've marked in green;dress and set.Ashley himself says:"It is the same knot as the Double Sheet Bend(# 1434).Frequently it will pull up into the form here illustrated,which is equally secure.".
P.S:I saw your EDIT, but it can be useful for other users ( and..I was about to post when I saw it!)
(http://)

Yes. What you say is true. Please forgive me for putting you to all that trouble. I really should have been quicker with my EDIT, but instead I spent too long thinking about how to write it. At least, your proof is valid, and Seaworthy, who started this thread, might benefit from studying it.

Have a nice weekend

Twine
Title: Re: Important Double Sheet Bend query
Post by: Luca on October 05, 2014, 03:04:37 AM
No problem Twine! You have solved a misunderstanding, I have seen  #1435 in ABoK!
 Have a nice weekend you too!
Title: Re: Important Double Sheet Bend query
Post by: Andreas on June 05, 2019, 05:58:52 PM
Unlike the other sheet bends, simons, lapps and zeppelin  mentioned here#488 is the only one that resisted slipping against pulling with bare hands using fishing line  (imagine the orange rope to be monofilament)

Title: Re: Important Double Sheet Bend query
Post by: Dan_Lehman on June 05, 2019, 10:03:11 PM
And #488 can be found in fishing nets sometimes.
But, it has been deemed insecure itself in some line
and there is at least one other net knot introduced
to handle such lines.  I found maybe just one bit
of netting with this novel knot, and otherwise got
some info from a Danish net maker about it --or about
a quite similar structure.

--dl*
====