Talk:Reef knot

comment
Since the ends of the knot aren't shown, people could tie a reef knot, or a thief knot. The drawing needs to be more clear. --Anon

Some ideas:

How about "The square knot has been taken up as a symbol by the Boy Scouts and is the first knot most Scouts learn, but there are usually other knots that are better in most applications. For instance, either the sheet bend or two bowlines are better for tying two ropes together."

"The square knot is also called the reef knot, as its primary use on sailing ships was for reefing, or tying up, sails."

Shouldn't the granny knot be on this page too? I don't care for the granny knot article, implies that granny is a legitimate knot, and not just a mis-tied reef knot.

Also, shouldn't this article include the explanation that the thief knot looks just like the reef knot or square knot and was traditionally used to catch a thief (who would see it (ends hidden) and assume it was a square knot when re-tying it after going through your ditty-bag? (could be worded better!) Ortolan88

I didn't change these because I wasn't sure if I was missing something, but I don't understand the following caveats:
 * "secure if wet.not secure if wet."
 * "Difficult to tie."

The first is contradictory and the second is contrary to experience. Every Tenderfoot can tie a square knot. Ortolan88

Yes, the explanation for the weird caveats is simple! - it's been cut-and-pasted from the selections offered in the template in the "Discussion" under Knots. Oops.

I've fixed it - I don't think wetness affects this knot, and I'd classify it as "generally insecure".

Also, the knot is less secure when tied with ropes of dissimilar characteristics, not more. We should be careful with advice like this!! I've added a paragraph about the insecurity and history of the reef.


 * Although I agree about the knot's insecurity, the article's tone seems a bit patronising. Perhaps the warning should be given after the article rather than repeated all the way through? Rls 21:25, 9 Jul 2004 (UTC)


 * Agreed. Will do. --Smack (talk) 19:42, 15 January 2006 (UTC)

capsized reef knot
I went ahead and moved the content from capsized reef knot here. I think capsized reef knot can be deleted.

bend knot? no way
This really isn't a bend. It's very dangerous when used that way. It should be reclassified.


 * How would you rather classify it? It may be a dangerous bend, but it's a bend nonetheless.  Furthermore, it's only dangerous if there's a risk of it being capsized.  I can't think of a good reason to avoid it to tie, say, a bandage on an injured person's limb.


 * Sure, a square/reef ("squareef", anyone?) knot can be used to tie a bandage, or anything else that is not under a direct lengthwise load (tying up bundles, closing bags, or with tucked loops to tie your shoelaces) but then I don't think it's a bend - it's more of a binding knot. I think the real risk here, though, might be that these days it is often the only knot people remember to tie, even Scouts, and as a result it often becomes the only knot they know (this may well be the *most* looked at article in knotting on Wikipedia for this very reason!) and they will then use it for virtually any situation which involves a piece of rope or string. Actually *classifying* it as a bend (as opposed to *mentioning* that it can be used as an unreliable and dangerous bend, which I totally agree with you on, but *classifying* it as something else) seems to me to add legitimacy to the POV of using it to tie two ropes together for the purpose of making a longer line. Come to think of it, maybe part of the problem is in the Wikipedia definition of bends and binding knots as they're not very clear at the minute, simply listing examples, and both lists mentioning the square knot. BTW, the Ashley Book of Knots, often still cited as the "bible" of knots, says "There have probably been more lives lost as a result of using a square knot as a bend (to tie two ropes together) than from the failure of any other half dozen knots combined". I'm also pretty sure that the IGKT would argue for it not being generally known as a bend. Are there any other citations that could back up either side of this argument? What do others think? - Adxm 20:40, 14 August 2006 (UTC)


 * I found another citation at one of the references at the bottom of this very article, "The Reef Knot Family" states that "The square knot or reef knot should only be used as a binding knot where it lies tightly against the surface of that which it binds and cannot move. Unfortunately, it is wrongly used as a bend where it has killed many." Adxm 20:44, 14 August 2006 (UTC)


 * Wikipedia shouldn't be in the business of saving lives, so the fact that people get themselves killed by trying to use the reef knot as a bend doesn't mean that we shouldn't list it as a bend. However, I'm willing to accept binding knot as an alternative. --Smack (talk) 03:09, 15 August 2006 (UTC)


 * So what exactly distinguishes a binding knot from a bend? The binding knot article states that some binding knots are held in place by friction against the load, but others just have knotted ends. These knotted-ends binding knots seem to be a specific application of a bend (albeit a non-critical one, in most cases). Presumably I could equally well tie up a parcel using a sheet bend or zeppelin bend - i.e. a bend can always be used as a binding knot. You (Adxm) say that a reef knot should not be used in situations with a direct lengthwise load - but even a pair of shoelaces must have some lengthwise load, otherwise the knot would serve no purpose. Mtford 08:21, 16 September 2006 (UTC)


 * I'll quote the ABoK again on this one:
 * The knots serve two purposes. Either they confine and constrict a single object, or else they hold two or more objects snugly together. (ABoK, Introduction to chapter "Binding Knots")
 * So I guess the emphasis here should be on snugness which will be hard to achieve using the regular bends. Also this snugness means a largely constant load on the knot. The knots usually referred to as bends have to be more jerk-resistant and need not be as easy to snug up. (My theory and suggestion for a definition.) --Netizen 12:36, 16 September 2006 (UTC)

Equivalent to two half-hitches?
Am I right in thinking that a reef knot is identical to two half-hitches, but loaded differently? In fact I think two half-hitches are really a "capsized" reef knot. The only difference is that one of the free ends in the reef knot becomes the standing end of the two half-hitches; the two standing ends of the reef knot form the loop around the post.

Mtford 12:39, 14 September 2006 (UTC)
 * The reef knot can be opened quickly by deliberately capsizing it. It then turns in a cow hitch which can be slid off. A cow hitch is indeed comprised of two half hitches. There is a nice animation at animatedknots that demonstrates that not even two reef knots on top of each other will prevent this failure.
 * Personally I'd use the word "related" rather than "equivalent". Here are two excerpts I found in the first Chapter of The Ashley Book of Knots, "On Knots".


 * A different way either of tying or applying a form generally constitutes a second knot. (ABoK re. knots #1 and #2)


 * There are even cases where a totally different knot may result when carelessly pulled. Tie the Granny Knot (#80) around any object and pull one end, and it will capsize into Two Half Hitches (#81). A Reef Knot (#77) may be capsized into Reversed Half Hitches (#1786) in the same manner. (AboK re. knots #80 and #81)


 * Since Ashley is still considered very much an authority, I'm probably safe quoting him here. ;)
 * Hope it helped, Netizen 20:07, 14 September 2006 (UTC)


 * I'd like to point out that not any pair of two half-hitches constitutes a valid two half-hitches. In particular, Ashley's "reversed half hitches" does not. --Smack (talk) 03:40, 15 September 2006 (UTC)


 * If by "not any" you mean "not *just* any" I agree with you. --Netizen 09:48, 15 September 2006 (UTC)


 * No, I think I meant to say "not every." (:  --Smack (talk) 19:55, 15 September 2006 (UTC)


 * Thanks - I hadn't noticed that my two half-hitches were reversed, but you are right. Interesting that a "granny knot" is stronger than a "reef knot" when they are capsized into the corresponding hitch knots. Mtford 08:04, 16 September 2006 (UTC)

Efficiency: 48%???
What on earth does this mean? 48% of what? I don't have any idea, and there's no clue in the article of where I should go to find out. Help! 86.132.143.24 02:27, 23 December 2006 (UTC)


 * I think that it means the loss of rope strength. In other words, a 100-kg-test rope with a reef knot will only hold 48 kg. --Smack (talk) 06:29, 24 December 2006 (UTC)

guides
guiding is good

diagram at bottom wrong
The knot diagrams at the bottom of the article show the hercules knot to be the same as the grief knot. The diagram should be changed to match the reef knot as the rest off then article says the hercules knot is another name for the reef knot. —Preceding unsigned comment added by 174.1.7.25 (talk) 11:11, 4 January 2010 (UTC)

To bend or not to bend
Does it seem strange that page says that the Reef Knot should not be used as a bend, yet the diagram shows it as one! While the diagram is clear and shows the knot well, it IS a bend of the red and blue ropes! Perhaps teh diagram should be just a single color to emphasize the reef knot is a binding knot and NOT a bend! Paulschn (talk) 06:10, 18 August 2010 (UTC)paulschn

tying two ropes together
Where it says "tying two ropes together", I put hyperlink to Flemish bend. It may not be the best choice,but,the idea was to have some knot mentioned which becomes second-nature(for quick rope joining). Note that 'Wikiproject icon'(File:Flemishbend.jpg) ,above, shows the knot. Another choice would be to hyperlink direct to 'List of bend knots' and have users decide from that. Maybe the double sheet bend would be better for this purpose? SignedJohnsonL623 (talk) 04:14, 16 November 2011 (UTC)

There is a difference between a square knot and a reef knot
There is a clear difference between the two. A reef knot will have a quick-release loop.

http://sailing.about.com/od/learntosail/a/basicsailingknotshub.htm 24.126.146.134 (talk) 00:29, 5 May 2012 (UTC)

Knot for evaluation, 'Kay88' or other.
Essentially this is two figure-of-eight knots but not a Flemish bend. Could this be classed as a bona fide knot/bend or just a weave or trivial knot?SignedJohnsonL623 (talk) 09:26, 29 December 2012 (UTC)
 * Hello JohnsonL623, I have replied on your user talk page... --Dfred (talk) 17:22, 29 December 2012 (UTC)

Binding Knots
All Binding Knots, are made to compress inwards on something for the Nip/securing pinch, so many make fair Hitches that Nip likewise against a host in it's grip. Square Knots typically shown as flat end to end knot, like Bend IN PICTURES. BUT, that loses the Nip against the host round object. Ashley's Book of Knots gives Square Knot an Anchor icon, yet Crossbones as Bend, and guestimated Square as BEND killed more men than all rest of knots. i will draw.Thetreespyder (talk) 01:25, 29 May 2019 (UTC)

Physical analysis
The section Physical analysis is unclear, and shows only result of analysis and not analysis itself. Worse, it also seems the only variable taken into consideration was coeficient of friction (I looked into Crowell, "The physics of knots" which was accessible online, but not the other one). Also, failiure of a knot is not only if it is undone (slips, capsizes...), but also if the rope itself (or cable or line...) breaks in, or because of the knot.

Real life
Several other variables influence failiure of a knot (including reef knot). Some of those depend on construction, other on other properties (not friction only) of material of the rope. Some of them are

Compressibility of the rope
It depends both on material(s) and construction: if a rope can be squeezed, it will deform under pressure in the knot in a way, that greatly increases resistance to slippage, and present model of (simplified) friction only will be invalid. That's easily verifiable with tying any knot on elastic rope, pulling it really tight and then trying to untie it again, but use a piece of bungee rope that is already destined to be discarded.

Diameter of the fibers
When fibers are bent (as they are in most knots), they may be bent above material's ability to bend without breakage. Radius of the the bend at breakage depends on material (including tempering etc.) and diameter of the fiber. E.g. for optical communication fibers those radii are specified in product documentation that can possibly be used as WP source. In general, the thinner the fiber, the smaller the radius of the bend, with the same material; but relation is not necessarily linear.

Elasticity of material
If material is less elastic, the fiber shall break sooner when bent (also not linear, out od relatively small interval where Hooke's law can be applied). Some of moduli of elasticity should be included into the model. E.g. some tough fibers of same dimension aren't alowed to be bent as much as some more elastical: kevlar and karbon fiber vs. poliester fibers come to mind; kevlar resistent to cut, and it and karbon to strech, but both fragile to overbend; poliester resistent to bend but cuttable, and more breakable by strech)

In knot inner fibers of the loop don't carry burden
It is similar as in single thick fiber bending, where inner part of loop is under compression and outer under tension, but less drastic. Reduction of ability to carry stress depends on radii of loops, construction and material of rope, and diameter of rope (also line or cable in nautical use). It can be modelled, but in this paragraph it is even not mentioned (at least roule of the thumb of estimating half safe working load of strain could be mentioned).

Professionals are trained to keep that in mind, and equipment (nautical bits and winches etc.) is sized according to that, but if somebody changes material used (wire cable where syntetic was used before etc.) all these should be reconsidered, but that might be owerlooked.

Resistance of material to material's fatigue
If (especially bending) stres is cyclic (as in real world applications, which usually, but not quite allways, are dynamic), material's ability to withstnading stress can deteriorate through time (several mechanisms, also not linear) far below original safe working load, and fail catastrophically.

Thermal properties of material(s), and construction
Whenever stress is dynamic, internal and external friction generate heath. Thermal conductivity of materials, dimensions, type of construction of rope, and environment's ability to absorb the generated heath influence working temperatures in prolonged use in such conditions. Properties of material(s) at temperatures involved decide what happens next (from melting, tempered steel in steel cables loosing properties, to chemical reactions including fire). People buying ropes for pleasure boats that can get into heavy weather should take termal considerations of their ropes very seriously when choosing what to buy for what purpose.

Environmental stability
Ultraviolet rays are part of physics, but results on ropes are materials science which includes chemistry and more; same with oxigen and other chemical influences of environment.

That's not all, it is just some of things you need to consider when troubleshooting things that went wrong. But producers of ropes (for climbing, nautical use etc.) need to address most of that, and wise user and buyer should be aware of that when choosing.

Conclusion
That paragraph on physics is deceptively oversimplified, and some better WP source should be found to address at least some of things above. Before that, it could be at least mentioned in it that it is and oversimplified estimate.

A lot of what I mentioned is probably already elsewhere in WP and could be referenced, instead of included. When (if?) I find time, I'll try to see about that, but anyone that can do some of that before me si seriously welcome. --Marjan Tomki SI (talk) 12:57, 6 January 2022 (UTC)