In defence of the sheet bend

[estarzinger]

Originally Posted by Seaworthy Lass

I have not had a reply from Evans regarding my question about whether or not he tightened up the Carrick well before loading it, but that would be useful info.

Sorry I have concluded I have done about as much 'theory' on this as I can, and I now just need to get it out under actual loads and learn more from real experience.

But Yes, I did pre-tighten it up, BUT with half of it being a loop it does not deform to the proper shape. The loop with both legs tensioned tugs it back to the un-deformed shape.

I actually have long experience with the double sheet bend on exactly this application (thru a dyneema loop to a steel chain hook) and it never failed. So it may well be that there is really no problem here to solve.

Obviously a splice would be best here, and I have finally found an authoritative source for splicing this "kermantle" line construction (Which is a quite different splice than for the marine double braid constructions)

So, my current plan is to use the 'supper snubber' for a month or so and see how I like it, swap in a similar (size/length) piece of 8 brait and see if I like that better or worse than the climbing line (I will lean toward the climbing line if I don't see any obvious improvement) and then after two months use, if I still like the supper sunbber, put splices in.

What's immediately obvious with the 'supper snubber' is that it's quieter than my prior stretchy snubbers, which used to squeak when stretching. The dyneema part of supper snubber to the roller obviously does not much much at all and all the stretching is taking place off the boat. The chain also seems to be quieter, which I think/hope means I have got the stretch 'just right' - no 'yo-yoing' and also no 'snatching'

[Seaworthy Lass]

Originally Posted by estarzinger

Sorry I have concluded I have done about as much 'theory' on this as I can, and I now just need to get it out under actual loads and learn more from real experience.

But Yes, I did pre-tighten it up, BUT with half of it being a loop it does not deform to the proper shape. The loop with both legs tensioned tugs it back to the un-deformed shape.

I actually have long experience with the double sheet bend on exactly this application (thru a dyneema loop to a steel chain hook) and it never failed. So it may well be that there is really no problem here to solve.

Obviously a splice would be best here, and I have finally found an authoritative source for splicing this "kermantle" line construction.

So, my current plan is to use the 'supper snubber' for a month or so and see how I like it, swap in a similar (size/length) piece of 8 brait and see if I like that better or worse than the climbing line (I will lean toward the climbing line if I don't see any obvious improvement) and then after two months use, if I still like the supper sunbber, put splices in.

What's immediately obvious with the 'supper snubber' is that it's quieter than my prior stretchy snubbers, which used to squeak when stretching. The dyneema part of supper snubber to the roller obviously does not much much at all and all the stretching is taking place off the boat. The chain also seems to be quieter, which I think/hope means I have got the stretch 'just right' - no 'yo-yoing' and also no 'snatching'

Thanks for reporting back.

That means Andrew is right listing sturdy attachment to a loop as a unique characteristic of a sheet bend/double sheet bend. The only possible problem would be when trying to attach a snubber which is thicker than the Dyneema loop. I don't know just how much difference it makes, but it is recommended the standing part of the loop be the thicker portion when the lines are of unequal size when tying sheet bends. The sharpness of the initial bend is one factor in knot strength and the thinner the standing loop, the sharper this bend will be.

Paul's twist did seem such a lovely simple solution to make a Carrick work (sorry Paul, you will need to leave the 'genius' bit out of your signature for now LOL).

[estarzinger]

By the way, I liked the look of that 'half a triple fisherman', but when I load tested it, it did something unexpected - the spectra started slipping down thru the middle of the 'barrel'.




I did not take a picture of the ultimate end result if you allow the slipping to go the whole way, but it is not pretty.

By the way, there is a 'blood knot' that looks like it might be adapted to work here (half a blood knot plus the loop) . . . anyone know anything about it?

[Seaworthy Lass]

Originally Posted by estarzinger

By the way, I liked the look of that 'half a triple fisherman', but when I load tested it, it did something unexpected - the spectra started slipping down thru the middle of the 'barrel'.

I did not take a picture of the ultimate end result if you allow the slipping to go the whole way, but it is not pretty.

I commented on that a few posts back:

Originally Posted by Seaworthy Lass

What you have tied here is simply a double overhand (like you use for a stopper knot). I would think this is worse than a sheet bend. The beauty of it used in a Double Fisherman's is that under load the two halves of the knot jam up against each other, which gives it its high holding ability.
I personally would not use this to join a line to a loop (nor would I use half a Triple Fisherman's).

Originally Posted by estarzinger

By the way, there is a 'blood knot' that looks like it might be adapted to work here (half a blood knot plus the loop) . . . anyone know anything about it?

I have only ever used this knot occasionally joining sections of tippet (similar diameter) when flyfishing. I would be very wary of joining halves of any knots to loops though - much of the strength from these comes from the knots butting up together.

[Seaworthy Lass]

Originally Posted by estarzinger

By the way, there is a 'blood knot' that looks like it might be adapted to work here (half a blood knot plus the loop) . . . anyone know anything about it?

There was a knot used to tie the tippet to the backing line though when fly fishing that utilised a loop. Can't remember the name of it, but I will tie it in rope in a sec and post a photo.

[Seaworthy Lass]

This was it. It was designed to tie the tippet (thinner, green and white in my photo) to the backing (thicker, black and white in this case). The backing formed a loop. More turns were generally put on the loop than I have shown.

With the use of slippery Dyneema/Spectra lines we do need new techniques for tying and looking to the sport of fishing may in fact be useful.

I have used a triple sheet bend with reasonable success on slippery polypropylene line. Is there any reason even a fourth turn can't be utilised? It would be great to have access to a testing bed using some of the newer line available and experiment with some knots.

This is the knot used to tie tippet to backing when flyfishing. If anyone wants instructions on how to tie it I will post photos:

Edited to add:
One big factor in knot strength is the distance from the first curve of a knot to where the full load is taken. This is a big reason why the humble double sheet bend performs reasonably well. I can only postulate a triple sheet bend would perform even better and knots like the one shown below may be better still.

[Paul Elliott]

Originally Posted by Seaworthy Lass

Paul's twist did seem such a lovely simple solution to make a Carrick work (sorry Paul, you will need to leave the 'genius' bit out of your signature for now LOL).

Oh well, that's not the first time one of my elegantly beautiful theoretical solutions was murdered by a gang of ugly facts!

I do see how it being a double-ended loop would cause it to not snug up properly under load. Which makes me wonder about the pretty "seized Carricks" I see in the books. I guess the seizing has to take a bit of the load in that case.

The other problem is the slippery line. The lack of friction has obviously made a lot of previously excellent knots become relatively useless, and it looks like the Carrick is one of them. Perhaps I should experiment with heavy fishing line (the 100 lb test stuff) the next time i consider knots for slippery synthetics.

This has been a great discussion. In general I do like the sheet bend and double sheet bend. I suppose I will need to revisit my knots in anticipation of having more of the slippery stuff on board. Currently all I have is the small-diameter Dyneema line I use for lashing. Everything else has a fairly rough cover.

[Seaworthy Lass]

Originally Posted by Paul Elliott

The lack of friction has obviously made a lot of previously excellent knots become relatively useless, and it looks like the Carrick is one of them. Perhaps I should experiment with heavy fishing line (the 100 lb test stuff) the next time i consider knots for slippery synthetics.

I have found the Carrick excellent on braided polyester, not tried it on Dyneema. I think the main reason it failed for Evans was that part of the load was being placed on what should have been a loose end.

Originally Posted by Paul Elliott

This has been a great discussion. In general I do like the sheet bend and double sheet bend. I suppose I will need to revisit my knots in anticipation of having more of the slippery stuff on board. Currently all I have is the small-diameter Dyneema line I use for lashing. Everything else has a fairly rough cover.

The triple sheet bend is great for slippery line .

Yes, more options need to be explored. I would love to know how that fishing knot I posted a photo of would work in practice on Dyneema.

Does anyone know what studies have been carried out on knot suitability for Dyneema? I can't find anything.

[estarzinger]

^^

this climbing knots has some information, but is oriented to climbers and is incomplete.

[Andrew Troup]

Thanks everyone

I must admit my heart is generally in my boots when I start a thread (so I try to avoid it, generally)
but on this occasion my most optimistic hopes were greatly exceeded.

Thanks everyone for for making this such a great thread:

wonderful insights and diligent investigation and inspirational swoops of lateral thinking.

Too many to enumerate, but you know who you are !

Evans - The only kernmantel splicing info I was aware of was at

New England Ropes - Splicing Guide

and I hesitated to post it, because the photo, to me, does not resemble any kernmantel I've encountered climbing

Have you found something that looks applicable to a finer cover? (Not saying that the New England method does not, just that I can't be sure it does...)

[Andrew Troup]

Originally Posted by Seaworthy Lass

....

I did not know an Alpine Butterfly was so much better than a Bowline. I have only used it on the bight ( not as an end knot). Given that it has no tendency to shake loose like a bowline I will start to use it more.

...

Seaworthy

Did you realise the Alpine Butterfly can also be used as a highly superior bend, to join two ropes?

I don't know if it outperforms the legendary Zeppelin bend, but what I most like about it is that it's one of those rare high-performing knots which are almost impossible to tie wrong-handedly.

Provided it's symmetrical in appearance, and both the tails come through from behind, it's good to go.

PS: The carrick bend, I have come to think, is pre-eminently suited to large stiff hawsers. Does anyone else share this feeling?

(Naturally the tails would be whipped .... or otherwise secured ....
duct-taped, presumably, in hillbilly or NASCAR circles )

ON EDIT: before anyone jumps down my throat, of course in practice I would leave the tails longer than shown, unless (for compactness) special precautions had been taken, eg the knot had been wetted and hauled tight using a winch or spanish windlass, then (once dry) the ends trimmed with a hot knife ....

[Seaworthy Lass]

Originally Posted by Andrew Troup

Seaworthy

Did you realise the Alpine Butterfly can also be used as a highly superior bend, to join two ropes?

I don't know if it outperforms the legendary Zeppelin bend, but what I most like about it is that it's one of those rare high-performing knots which are almost impossible to tie wrong-handedly.

Provided it's symmetrical in appearance, and both the tails come through from behind, it's good to go.

PS: The carrick bend, I have come to think, is pre-eminently suited to large stiff hawsers. Does anyone else share this feeling?

Hi Andrew
Yes, I was aware the Alpine Butterfly can be used as a bend. It is actually my preferred method of joining two lines of similar size. Its security is good and it can be untied after a heavy load. It is not quite as good as the Zeppelin apparently, but I use it as there is little difference and it is a knot I am very familiar with and could do it by feel alone (I tie it around my fingers using the same technique for both as a loop and bend). Anything that is ingrained in muscle memory like that is useful in an emergency .

I agree about the Carrick and heavy line. I think it is in its element for that purpose. But it is also more secure than a sheet bend (both in breaking strength and having less (no?) tendency to shake loose, so when Paul came up with that lovely twist idea it seemed a better alternative to the sheet bend. Wasn't to be due to load distribution .

I really think knots need reinvestigating now that Dyneema/Spectra is in use. The link to the article that Evans posted clearly demonstrates this.

[Wotname]

Originally Posted by Bash

...............

You started a thread called "in defence [SIC] of the sheet bend." I'll presume you meant "defense." So, I'm listening: defend all you want. I you want to go on attack, however, think again.

Presumably this was TIC however for the less knowledgeable, "defence" is correct unless you are USA indoctrinated

[estarzinger]

By the way . . . . one more thing to mention is cleating off bare dyneema single braid. I am using a tug boat hitch (which is quite easy and simple and appears not to slip) rather than the conventionally 'yachty cleating pattern' which appears to very very slowly (a couple inches per day) slip when under decent cyclic loading.

The dyneema mooring buoy pennants used spliced end loops, perhaps in part to solve this, but I want to be able to cast off a snubber immediately so don't think that's the best idea for this application.

I could use Dacron covered dyneema (double braid), rather than dyneema single braid, and I believe that would not slip round the cleat and would have the added advantage of UV protection. I will have to think about this (I have some old dyneema double braid halyard material n board). It would add some bulk (I love how light and compact the dyneema single braid is) and make the splicing a bit more complex.

[savoir]

Originally Posted by Wotname

Presumably this was TIC however for the less knowledgeable, "defence" is correct unless you are USA indoctrinated

Correct. Not everyone speaks Americanese but try telling that to an American.