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Old 28-05-2013, 12:24   #46
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Re: In defence of the sheet bend

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Originally Posted by estarzinger View Post
What do you all think of the below . . . .

Attachment 61438

It's half of a double fisherman, tied to the dyneema loop. It does not slip. It will be much harder to untie than the sheet bend, if I ever have/want to. DO you think stronger or weaker than the sheet bend?
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).
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Old 28-05-2013, 13:46   #47
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Re: In defence of the sheet bend

Not too sure if its applicable, but I tied a double zeppelin joining a 3/16" polyester cord to 3/4" nylon 3 strand and it doesn't seem to have any potential to slip. I can't proof test it, but I also can't generate any slippage.
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Old 28-05-2013, 17:57   #48
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Re: In defence of the sheet bend

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Originally Posted by Seaworthy Lass View Post
And this is the completed Triple Fisherman's.

It is an extremely useful knot to learn as it works well joining two slippery lines of roughly the same diameter. Works so well that the knot just about welds together under high load:
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On a side note I used to have access to a test bed and I did a few tests on climbing rope knots. The results surprised me, with a double fishermans bend failing before a single fishermans bend and an alpine butterfly knot. It seemed like the heat generated by the slippage through the double fishermans bend could not escape fast enough and the rope melted, breaking in the middle of the knot. Maybe this could be a downside to the double sheet bend or any bulky knot?
Interesting knot, and great pictures Seaworthy Lass, thanks.

I was thinking some more on why the double fishermans might have failed so quickly in my test, and this would imply that the triple would be as bad or maybe even worse. The problem seems to be that the loaded part of the rope is buried and well insulated inside the knot, so any heat generated by friction and elasticity is trapped, building up until it melts. the heat must be large as it melted the cover of the kernmantle rope we were testing.

Knots like the sheet bend have the loaded part more on the outside where any heat buildup can escape. unfortunately I didn't test a sheet bend. But the bowline held up much better than the double fishermans bend.

The way I was taught, the carrick bend really was supposed to have seizings on the tails to keep it more open. With a stiched and seized tail the knot would look very nice, but maybe a cow hitch would work just as well in this case, with a well seized and stiched tail instead of a splice?
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Old 28-05-2013, 19:04   #49
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Re: In defence of the sheet bend

^^ An interesting link. that seems to contradict the double fishermans bend criticism in my previous post. but I know what I saw with my own two eyes!

http://www.paci.com.au/downloads_pub...tute_Tests.pdf

Maybe some strong but slow pre-loading would significantly increase the strength of the Double fishermans bend due to it compacting. I do remember a whole lot of rope creeping out of the Double fishermans as it was tightened on the hydraulic test bed.
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Old 28-05-2013, 19:30   #50
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Re: In defence of the sheet bend

I must confess to having a bit of concern about using hitches (designed for fastening to something rigid like a bail, rail or ring) to fasten to a sling

... as opposed to using a bend, designed to join two ropes.

(I should clarify that I consider a fisherman's bend to be a hitch, if you take my drift.
It doesn't help that what's usually called a "fisherman's knot" is a bend - go figure !)

My first thought when Evans popped the tricky question further up about how to attach a climbing rope to an HDPE sling was something neat and compact and outrageously secure like a buntline hitch, given he didn't need to be able to untie it,

but despite being an awesome knot, it seems to me that it is ill suited to fastening to a deformable sling, because it forces that sling to a single, small radius U shape, and doesn't spread the frictional interface at all. A bit like a domino rope clutch with only one domino...

The cow hitch seems better because it has twice the width of cordage inside the U-bend of the sling, but it's still a bit like a 'single domino', just wider....

Whereas the two bends which seem to lend themselves to this unusual situation (sheet bend and carrick bend) induce several reverse bends in the deformable sling, sharing the load, a bit like a domino clutch with three or four dominoes...

I do think it's necessary to set aside the usual received wisdom and personal experiences around bends when considering adapting them to attach a rope to a sling.

Both legs of the sling are under tension, which changes the structure of the bend, as well as the stress paths. The bends were designed for one leg to be a free tail.

They may perform considerably better in the sling application, or considerably worse.
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Old 28-05-2013, 20:15   #51
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Re: In defence of the sheet bend

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Originally Posted by Snowpetrel View Post
^^ An interesting link. that seems to contradict the double fishermans bend criticism in my previous post. but I know what I saw with my own two eyes!

http://www.paci.com.au/downloads_pub...tute_Tests.pdf

Maybe some strong but slow pre-loading would significantly increase the strength of the Double fishermans bend due to it compacting. I do remember a whole lot of rope creeping out of the Double fishermans as it was tightened on the hydraulic test bed.

Maybe the percentage of knot strength vs line strength depends on the type of line used. Also the 'snugness' of the initial knot must affect results. Loaded the forces will not necessarily tighten it in the same manner.

It was an interesting article. 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.

By the way, I now give Bowlines a Yosemite finish after a CF member suggested this to prevent them from shaking out. I wonder how this affects the breaking strain of the knot doing this?

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.
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Old 28-05-2013, 21:01   #52
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Re: In defence of the sheet bend

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Originally Posted by Seaworthy Lass View Post
Maybe the percentage of knot strength vs line strength depends on the type of line used. Also the 'snugness' of the initial knot must affect results. Loaded the forces will not necessarily tighten it in the same manner.

Very true, and I suspect this was the case in my trial. It was a shame I only did one test.


By the way, I now give Bowlines a Yosemite finish after a CF member suggested this to prevent them from shaking out. I wonder how this affects the breaking strain of the knot doing this?

Yosemite finish? sounds interesting, can you explain, and how has it worked out on the boat for you?

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.

I am sure he will try it or find an even better solution I have been very impressed with his dedication to finding the very best solution and then sharing his findings.
.....
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Old 28-05-2013, 21:24   #53
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Re: In defence of the sheet bend

Yosemite finish on Bowline to prevent unshaking of the knot.

Step 1:
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Old 28-05-2013, 21:25   #54
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Re: In defence of the sheet bend

Yosemite finish on Bowline to prevent unshaking of the knot.

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Old 28-05-2013, 21:26   #55
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Re: In defence of the sheet bend

Yosemite finish on Bowline to prevent unshaking of the knot.

Step 3:
Attached Thumbnails
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Size:	142.6 KB
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Old 28-05-2013, 21:28   #56
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Re: In defence of the sheet bend

Yosemite finish on Bowline to prevent unshaking of the knot.

Appearance of the tightened knot:
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Old 28-05-2013, 21:33   #57
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Re: In defence of the sheet bend

Historical note: This knot (two loops and return the tail) is the signature knot invented by Layton Kor hence the Kor Knot. Yours is a variation of the original.

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Old 28-05-2013, 21:36   #58
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Re: In defence of the sheet bend

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.....
Yosemite finish? sounds interesting, can you explain, and how has it worked out on the boat for you?
Don't laugh, but I have found it infinitely useful for cleaning the stanchions. I use WD40 and a pad, then wipe them with a rag. As I don't want to put the WD40 soaked pad on the deck I poke a hole in the edge of the pad, secure a line, then tie it around my wrist. The bowline is the easiest knot for me to tie with one hand. Until I started using a Yosemite finish I lost countless pads overboard, even when I left really long tails .

It is a minor task, but it really illustrated to me how poor the bowline was if it is not under continual load.
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Old 28-05-2013, 21:41   #59
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Re: In defence of the sheet bend

^^ Thanks Seaworthy Lass, looks like a very useful variation. Do be careful with dat WD 40 though...
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Old 28-05-2013, 21:53   #60
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Re: In defence of the sheet bend

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Do be careful with dat WD 40 though...
Thanks for the alert. Will instantly remove it from our stateroom
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