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Old 07-03-2015, 21:15   #76
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Re: Knots

Well I've just given it a go...and its a no go....

I'm on Campo del Pingo just now so no winch available but I did try it on the wench. She stuck on a blue so maybe I'll need to find a boy scout.

I did try it on random bits of string, an old mainsheet out of the back of the truck, a bit of Telstra conduit 'pull through' and some slippery stuff from Bunnings.... all held just fine.

I find it odd that you say 'sheet bend no good... bowline good ' as they are the same 'knot'. Well the bowline is a knot, the sheet bend is a bend.. Only diff is that the bowline involves one bit of string, the sheet bend two....

What exactly do you use a sheet bend in a snubber for?

I've been using sheet bends since Noah was a deck boy (OK slight exaggeration) retired to a hill farm life style block on the slopes of Mt Ararat and have never had one fail in big ropes or small.
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Old 07-03-2015, 21:32   #77
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Re: Knots

Quote:
Originally Posted by El Pinguino View Post
Well I've just given it a go...and its a no go....

I'm on Campo del Pingo just now so no winch available but I did try it on the wench. She stuck on a blue so maybe I'll need to find a boy scout.

I did try it on random bits of string, an old mainsheet out of the back of the truck, a bit of Telstra conduit 'pull through' and some slippery stuff from Bunnings.... all held just fine.

I find it odd that you say 'sheet bend no good... bowline good ' as they are the same 'knot'. Well the bowline is a knot, the sheet bend is a bend.. Only diff is that the bowline involves one bit of string, the sheet bend two....

What exactly do you use a sheet bend in a snubber for?

I've been using sheet bends since Noah was a deck boy and never had one fail in big ropes or small.
I've been kind of thinking this too. I'm certainly willing to give the Zeppelin a try, but I've been wondering when exactly it is a sheet bend isn't fine.

So, if I'm tying two tow lines together, it's an emergency tow. So I'm not loading and unloading- well, I am. I'm loading to get them out of immediate danger, then unloading to get them off the make shift tow line, then rigging a proper tow line with no bends in it. To tow them- where ever.

Even my 35' cruising sailboat has at least two suitable tow lines. My kedge line and my starboard anchor Rhode (port is chain).

Now, I don't have a ton of commercial towing experience, but I have a so-so amount of rescue towing experience. I just can't see myself needing to leave a bend in a tow line for an extended period of time.

My other concern with this knot is a lack of familiarity with seamen at large, are they going to know how to untie this knot if I tie it?

Like I said though, I havent ever tried the knot, I am happy to do some experimenting with it, but their are some questions I ask myself about it.

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Old 07-03-2015, 21:36   #78
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Re: Knots

Quote:
Originally Posted by El Pinguino View Post
Well I've just given it a go...and its a no go....

I'm on Campo del Pingo just now so no winch available but I did try it on the wench. She stuck on a blue so maybe I'll need to find a boy scout.

I did try it on random bits of string, an old mainsheet out of the back of the truck, a bit of Telstra conduit 'pull through' and some slippery stuff from Bunnings.... all held just fine.

I find it odd that you say 'sheet bend no good... bowline good ' as they are the same 'knot'. Well the bowline is a knot, the sheet bend is a bend.. Only diff is that the bowline involves one bit of string, the sheet bend two....

What exactly do you use a sheet bend in a snubber for?

I've been using sheet bends since Noah was a deck boy and never had one fail in big ropes or small.
A simple sheet bend will hold extremely well if the lines are a similar diameter, if well dressed before any sudden load is applied and if the load is not constantly being applied and released. This is very limiting. If another bend can be used almost universally (it is not good in "slippery stuff", but very little is, including the sheet bend), why not substitute it?

The reason the bend was used in a snubber is that we needed to let out more scope quickly in one anchorage as the wind was unexpectedly rising (long tale why more scope was not possible initially). Instead of pulling in the chain until the snubber could be untied and the chain extended, it was simpler to just add more snubber.

The bowline and sheet bend may be 'the same' knot, but in practice they are very different, as load is applied to just the standing end in the latter and both 'ends' (ie the loop) in the former.
I agree the sheet bend holds very well in certain circumstances, but these are limited. Why mess with a series of bends, when just one will handle everything?

El, if you are happy, just continue as is, but if you want to test it out, just applying load by hand does not actually tell you much .

SWL
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Old 07-03-2015, 21:48   #79
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Re: Knots

Quote:
Originally Posted by FamilyVan View Post
My other concern with this knot is a lack of familiarity with seamen at large, are they going to know how to untie this knot if I tie it?

Like I said though, I havent ever tried the knot, I am happy to do some experimenting with it, but their are some questions I ask myself about it.
Untying it is amazingly child's play. It can be done single handed after high load for an extended time.

The easiest technique for undoing it with one hand is to use your last three fingers to support the knot, then push down the standing end of the side being released with your forefinger and push the 'throat' over the standing end with your thumb:
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Old 07-03-2015, 22:45   #80
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Re: Knots

In the interests of scientific research and in the spirit of the assorted anchor tests we see on CF I set the Pingmobile up as a test bed ( a quiet Sunday arvo here).
Ropes involved
12mm mainsheet as the 'puller' attached to the back of the Triton.

6mm Bunnings polyprop ( green)
6mm old Telstra stuff ( blue and yellow)
3mm Polyester with a bit of age on it ( red)

The method - secured the above three to a tree... mainsheet cowhitched to towball on Triton

Connected in turn.... went dead slow ahead in Triton and put foot on clutch as load came on but put all under plenty load ( stalled the ute once ).

Surged each one a number of times steadily increasing load.

Test 1, red 3mm, under heavy load, small stuff pulled through the eye of the mainsheet and near decapitated the dog.
Test 2, red 3mm, 'firmed up' bend a bit better, broke between truck and tree, dog buggered off. Unable to undo the bend.
Test 3, blue/yellow, rope started to strand, bend ok and could undo.
Test 4, green, stalled truck, continued surging until thought tree was going to come down on top of me....unable to undo bend
Photos should be self explanatory..
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Old 07-03-2015, 23:12   #81
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Re: Knots

Okay, if you stalled your truck with that line. You need a bigger truck. In fact- you just need a decent sized motorcycle.

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Old 07-03-2015, 23:22   #82
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Re: Knots

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Originally Posted by FamilyVan View Post
Okay, if you stalled your truck with that line. You need a bigger truck. In fact- you just need a decent sized motorcycle.

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Probly would have stalled with no string out the back...took foot of clutch while forgetting was in gear.... thats what happens when dog bites you......... I'll try a cow in the morning....
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Old 07-03-2015, 23:25   #83
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Re: Knots

Quote:
Originally Posted by El Pinguino View Post
In the interests of scientific research and in the spirit of the assorted anchor tests we see on CF I set the Pingmobile up as a test bed ( a quiet Sunday arvo here).
Ropes involved
12mm mainsheet as the 'puller' attached to the back of the Triton.

6mm Bunnings polyprop ( green)
6mm old Telstra stuff ( blue and yellow)
3mm Polyester with a bit of age on it ( red)

The method - secured the above three to a tree... mainsheet cowhitched to towball on Triton

Connected in turn.... went dead slow ahead in Triton and put foot on clutch as load came on but put all under plenty load ( stalled the ute once ).

Surged each one a number of times steadily increasing load.

Test 1, red 3mm, under heavy load, small stuff pulled through the eye of the mainsheet and near decapitated the dog.
Test 2, red 3mm, 'firmed up' bend a bit better, broke between truck and tree, dog buggered off. Unable to undo the bend.
Test 3, blue/yellow, rope started to strand, bend ok and could undo.
Test 4, green, stalled truck, continued surging until thought tree was going to come down on top of me....unable to undo bend
Photos should be self explanatory..
You really take your CF seriously. I think you should be honoured with some sort of honorary award, sugh as CF official tester.
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Old 07-03-2015, 23:29   #84
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Re: Knots

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Originally Posted by Rustic Charm View Post
You really take your CF seriously. I think you should be honoured with some sort of honorary award, sugh as CF official tester.
Only if Gin , Rum or fine red wine is involved....
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Old 07-03-2015, 23:34   #85
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Re: Knots

Quote:
Originally Posted by Rustic Charm View Post
You really take your CF seriously. I think you should be honoured with some sort of honorary award, sugh as CF official tester.
Me too .
Good on you El! Just keep your poor dog out of the way .

El, the "firming up" you refer to is what I mean by "dressing" the knot. It is really critical for high loads, particularly if the load is applied quickly. I did not work out the importance if this until quite recently (winch tests - I love playing too ). Only very rare knots do not require dressing - the Zep is one.

One comment is that for the main line you are using old rough, salt and UV stiffened mainsheet with probably a reasonable grip. Failure is generally higher for newer smoother line.

El, have you tried the Zep yet?
Try exactly the same lines as you used for the sheet bend and also then see how easily you can untie them.
The instructions for the Zep with photos are in earlier posts on this thread.

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Old 07-03-2015, 23:38   #86
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Re: Knots

Quote:
Originally Posted by El Pinguino View Post
Only if Gin , Rum or fine red wine is involved....
That's exactly the problem. Grey truck- fine red wine. You won't get accurate results unless you use a fine red truck and cheap grey wine.
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Old 07-03-2015, 23:47   #87
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Re: Knots

Quote:
Originally Posted by Seaworthy Lass View Post
Me too .
Good on you El! Just keep your poor dog out of the way .


El, have you tried the Zep yet?
Try exactly the same lines as you used for the sheet bend and also then see how easily you can untie them.
The instructions for the Zep with photos are in earlier posts on this thread.

SWL
Not tried it yet...manana...

I wonder if the issue you had with the snubber was down to on section being nylon.
Under load its diameter decreases while that doesnt happen to the old sheet you are using ... so maybe a very gradual 'creep' letting the nylon tail escape ?

I have had 'issues' with three strand nylon when used as an anchor rode in 'surge' conditions where splices were doing a fine job unlaying over a few days.

PS I made up all the dog stuff... lazy bugger just sat in the cab.....
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Old 07-03-2015, 23:59   #88
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Re: Knots

Quote:
Originally Posted by El Pinguino View Post
Not tried it yet...manana...

I wonder if the issue you had with the snubber was down to on section being nylon.
Under load its diameter decreases while that doesnt happen to the old sheet you are using ... so maybe a very gradual 'creep' letting the nylon tail escape ?

I have had 'issues' with three strand nylon when used as an anchor rode in 'surge' conditions where splices were doing a fine job unlaying over a few days.

PS I made up all the dog stuff... lazy bugger just sat in the cab.....
This is an underwater shot of the Zep I took last year when it was used to extend our snubber. The first time I had used it for an absolutely critical high load situation. Look at how the diameter of the standing part is much thinner as it is under load. No creep occurred.

The Zep seems immune to just about anything situation you care to throw at it apart from using slippery polyethylene (including the HMW stuff like unsheathed Dyneema).

This bend was loaded and unloaded and yanked about as the boat moved around and the gusts hit for about 48 hours of constant 25-35 knots with higher gusts. Zero slippage. After two days it undid with one hand.
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Old 08-03-2015, 03:49   #89
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Re: Knots

Quote:
Originally Posted by El Pinguino View Post
A little factoid some may knot know...
The bowline and the sheet bend are - mechanically - the same 'knot'.... just that the bowline involves one bit of rope while the sheet bend 'bends' two together....
Quote:
Originally Posted by Seaworthy Lass View Post
The bowline and sheet bend may be 'the same' knot, but in practice they are very different, as load is applied to just the standing end in the latter and both 'ends' (ie the loop) in the former.
I agree the sheet bend holds very well in certain circumstances, but these are limited. Why mess with a series of bends, when just one will handle everything?
I could just see many members reading these statements and shaking their heads in disbelief that the knots were the "same" so I have tied a bowline and sheetbend and presented them below.

I challenge anyone to tell me which is which .

Knot 1:
Is this a bowline or sheetbend?
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Old 08-03-2015, 03:52   #90
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Re: Knots

Knot 2:
Is this a bowline or sheetbend?

Not a trick question, there is one of each in these two photographs

The reason they behave differently is that they are loaded differently.
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"To me the simple act of tying a knot is an adventure in unlimited space." Clifford Ashley
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