Different way of whipping and hanging (Double Sheet Bend)

**Rat** · 03-01-2008, 15:54

TiredFeet is right, the Left Handed Sheet bend isn't as secure as the properly tied Sheet Bend (or Double Sheet Bend); especially with frequent loading and unloading (like a hammock is subject to). Both free ends should be on the same side.

Also, it is very easy to mess it up and tie a Reef Knot, a Reef Knot will spill very easily once it capsizes (one of the reasons it is used to furl sails) and is a pain to untie after loaded.

**Youngblood** · 03-02-2008, 08:24

Originally Posted by TiredFeet

Ashley says the sheet bend ends with both free ends on the same side of the knot. If they are on opposite sides, he calls it the left hand sheet bend and his tests indicated that the left hand sheet bend isn't as secure, i.e., it tends to comes loose under load more easily. He defines "security" as the amount of stress a knot will endure before it slips.

He also states that the double sheet bend is no stronger, but it is more secure.

Grog illustrates the sheet bend the same as Ashley.

About the terms "strength" and "security" for knots-- you defined "security" as the amount of stress a knot will endure before it slips. Is "strength" how much the tension is reduced before the rope breaks at the knot?

I would think that with a sheet bend knot that those terms could vary wildly because of the different materials involved. With most knots, they are tied back on to themselves so the radius of the bends in the knot itself is more uniform in proportion to the diameter of the rope. A sheet bend involves two different materials with varying diameters and texture, making me think that you would have to test each specific application.

**TiredFeet** · 03-02-2008, 18:12

Originally Posted by Youngblood

About the terms "strength" and "security" for knots-- you defined "security" as the amount of stress a knot will endure before it slips. Is "strength" how much the tension is reduced before the rope breaks at the knot?

Knot my definition, I was quoting Ashley, "The Ashley Book of Knots", p. 16. Considered the "go to reference" for all things knots. He defines "strength of a knot" as

"is determined by the stress it will endure before it breaks. To determine strength a material is required that will break before it slips.

His complete definition of "security of a knot":

is determined by the stress it will endure before it slips. To determine security a material is required that will slip before it breaks.

Originally Posted by Youngblood

I would think that with a sheet bend knot that those terms could vary wildly because of the different materials involved. With most knots, they are tied back on to themselves so the radius of the bends in the knot itself is more uniform in proportion to the diameter of the rope. A sheet bend involves two different materials with varying diameters and texture, making me think that you would have to test each specific application.

To continue quoting Ashley:

Some especially made mohair yarn, of a large size and even quality was provided, and I made myself some testing apparatus of materials secured from a local junk yard.

My test of security consisted of a series of uniform jerks applied at an even rate of speed, using the drip of a faucet for a metronome. A bag of sand provided a weight, and the jerks were continued until they either amounted to one hundred in number or else the knot slipped.

Only bends were tested. Ten bends of each kind were tied with the ends trimmed to an even length. Only six knots failed to slip and only one of these was a well-known knot. One knot slipped at the first jerk each time it was tried, and other well-known knots gave unexpected results. These will be found tabulated on page 273.

During the course of these experiments another question suggested itself which was: what effect, if any, has the direction of the lay or twist of rope on the security of the knot?

Right-laid rope and left-laid rope have opposite torsion. It was found that the regular RIGHT-HAND SHEET BEND (#66), tied in the two different lays, slipped at about the same average rate, but the variation of the number of jerks required was about twice as great for the left-laid as for the right-laid rope, which suggests that the latter is more reliable.

The RIGHT OVERHAND BEND (#1410) showed a ration of about two to three in favor of right-laid rope. An inferior material was used for these experiments, the excellent material of earlier experiments being exhausted, so the actual firgures of the experiments are not reliable.

To prevent slipping, a knot depends on friction, and to provide friction there must be pressure of some sort. This pressure and the place within the knot where it occurs is called the nip. The security of a knot appears to depend solely on its nip. The so-called and oft-quoted "principlke of the knot," that "no two parts which would move in the same direction, if the rope were to slip, should lie alongside of and touching each other," plausible though it may appear, does not seem important. Even if it were possible to make a knot conform to any extent to these exacting conditions, it still would not hold any better than another, unless it were well nipped.

An excellent example of this is the SHEET BEND. The SHEET BEND (#66) violates the alleged "principle" at about every point where it can, but it has a good nip and does not slip easily. The LEFT-HAND SHEET BEND conforms to the so-called "principle" to a remarkable extent, but has a poor nip and is unreliable.

It does not appear to make much difference just where the nip within a knot occurs, so far as security is concerned. but the knot will be stronger if the nip is well within the structure.

The emphasis (italics) are those of Ashley. I have also made it bold becuase the italics didn't show well on my display.

He goes on to describe his strength tests and to describe his apparatus. He includes drawings of the apparatus as well.

A lot of people (most?) would not consider his tests very scientific by todays standards because of his use of a water drip instead of a quartz stop watch and the lack of carefully calibrated gauges with the calibration traced back to national standards, etc, etc., etc. But very few people today have been willing to put the time and effort into conducting tests of knots in any manner whatsoever.

As you say, the security and strength of a knot will depend on the materials used. This occurred to Ashley also and he tested the different materials available and widely used at the time.

**Youngblood** · 03-02-2008, 18:52

Thanks TiredFeet.

**TiredFeet** · 03-02-2008, 19:45

Originally Posted by Youngblood

Thanks TiredFeet.

For anybody that is at all interested in knots, I highly recommend Ashley's book. It seems to be the "Gold Standard" and is referenced by practically all who work with knots (the usual "ABOK #xxx reference refers to knot xxx in "The Ashley Book of Knots".) I think I read somewhere that it is currently out of print, but Amazon has it in stock, so either it is still being printed or they have a pretty good inventory.

**Schneiderlein** · 03-04-2008, 15:05

Ok, so I am ready to give the double sheet bend a try. Two quick questions:

Is there any preferred direction in which to fold the hammock fabric? If I hold the end of the hammock in my hand and look along the length of the hammock, should I fold to the right, left, top, or bottom? Does it matter at all?
I am using a 3mm rope attached to a cinch buckle with a Prusik. Should I tie the sheet bend with a single strand of rope, or would there be any advantage in doubling up and using both strands?

**Youngblood** · 03-05-2008, 11:29

Originally Posted by Schneiderlein

Ok, so I am ready to give the double sheet bend a try. Two quick questions:

Is there any preferred direction in which to fold the hammock fabric? If I hold the end of the hammock in my hand and look along the length of the hammock, should I fold to the right, left, top, or bottom? Does it matter at all?
I am using a 3mm rope attached to a cinch buckle with a Prusik. Should I tie the sheet bend with a single strand of rope, or would there be any advantage in doubling up and using both strands?

I don't think which direction you fold the fabric to form the bight has any effect on the lay of the hammock. The only thing I could think of was that it might make a difference if water ever came down the suspension line all the way to the hammock knot. If the folded fabric was pointing downward it might divert some of the water away from the hammock some like a drip line would... but that takes a little imagination to see that happening. I might give that a try one day and see how it does. IMO, anything you can do to help with water is worth a look.

As far as the rope goes, I think you have to try it and see how it does. A lot of ropes are made up of multiple ropes that are twisted together so having small diameter rope doubled up doesn't sound like a problem.

**alex30808** · 03-08-2008, 21:22

Got any photos?

**macfly** · 05-13-2008, 19:22

I replaced the stock webbing on my Speer IIIA with 5/32" Spyderline. Here's my attempt at a slippery double sheet bend. The Spyderline is attached to the SMC rings, but pretty soon here I'm gonna have to bite the bullet and order some cinch buckles.

**Narwhalin** · 06-17-2008, 16:35

I tried this on a mini hammock I am making out of bug netting that I am going to use as a gear loft. I pulled the exposed end of the hammock and the hammock body in different directions, and the knot came undone. Did I do something wrong when tying the knot, or is this just the nature of that knot?