Author Topic: best advice for towing  (Read 18613 times)

Hereward

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Re: best advice for towing
« Reply #15 on: January 29, 2010, 05:56:36 PM »
Gosh. I have been away for a few days and there is a lot in these replies. Lots of good advice but clearly no straightforward answer.

Thanks for all the replies

Dan_Lehman

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Re: best advice for towing
« Reply #16 on: January 29, 2010, 08:37:52 PM »
Lots of good advice but clearly no straightforward answer.

You can't expect a "straightforward answer" for a problem that is only
loosely defined.  So, the various answers might be appropriate for various
situations as you might encounter.  Give us more constraining details of
your situation, and you might see some narrowing of responses -- but
there are still usually many ways to solve the problem.

Cheers,
--dl*
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Hereward

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Re: best advice for towing
« Reply #17 on: January 30, 2010, 11:46:23 AM »
You can't expect a "straightforward answer" for a problem that is only
loosely defined. 

I wasn't really expecting an easy answer. I particularly appreciated the empirical studies for which a link was provided. It has set me thinking of doing some of my own. Particularly in regard to snatch loads.  Ah well, something to think about for the summer.

sharky

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Re: best advice for towing
« Reply #18 on: January 30, 2010, 06:38:34 PM »
Can't go wrong with 28mm eight strand nylon...you can lift cars with that stuff...can't get more direct than that...
Sharky

Walter Seltzer

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Re: best advice for towing
« Reply #19 on: May 11, 2010, 11:59:23 PM »
There are three knots I prefer for this purpose:

 1. Bowline
 2. Bowline
 3. Bowline

They hold, maintain rope strength, any sized loop you need and are easy to untie.  And, there are many ways to tie them... straight up, in a bight, etc.


It is one of the six essential knots I insist my deckhands know before even getting on the boat.

Cap't Walter M Seltzer
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jcsampson

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Re: best advice for towing
« Reply #20 on: June 01, 2010, 11:54:37 PM »
Quote from: Hereward
". . . what knots . . . with what type of rope [?] . . ."

Hi Hereward,

If the rope that you are to use is made of man-made materials and has a safe working load that can meet the demands of towing, then the type of rope (such as solid-braid, hollow-braid, twisted, and kernmantle) is not likely to matter much. Twisted tends to be stronger and less expensive than braided, but it has that annoying tendency to . . . untwist. And the sheaths of kernmantle have that annoying tendency to . . . wear easily to expose the core, putting you in the position of having to buy more rope more often. (Rope manufacturers love kernmantle.) Hollow braids can flatten, but should still be suitable for many applications.

I don't know the specifics of the connecting hardware that you'll be using in your towing operations, so it's difficult for me to be specific. Even with standards, there may be enough subtle variations from one vehicle to the next. . . .

When you need to hitch, I would recommend structures that result in more than one turn or loop around the hardware. If you have access to an adequate length of thick-enough rope, and the span between vehicles allows for it, I would recommend running the rope a number of times back and forth between the two vehicles, being certain that there is no way for the rope to pop off the hardware.

Therefore, if I had to tow, I would probably find a secure way to have the rope run back and forth three times: Over the hardware of Vehicle 1, under the hardware of Vehicle 2, over the hardware of 1, under the hardware of 2, over the hardware of 1, under the hardware of 2, until the rope has wrapped three times around the hardware of each vehicle. Then, I would use my favorite bend to join the rope ends, which happens to be Hunter's Bend. (The Zeppelin Bend is another good choice, but I dislike that diagonally lopsided beast that has no identifiable front and back. They say that it's easy to untie, but unfavorably, it's easy to untie even when you don't want to untie it. Hunter's Bend is easy to untie [when you're damn good and ready] by holding the tails at the front of the knot and, with the other hand, pulling the side bumps down.)

JCS

roo

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Re: best advice for towing
« Reply #21 on: June 02, 2010, 12:14:44 AM »

Hi Hereward,
He hasn't been active for many months, incidentally.


Quote
Therefore, if I had to tow, I would probably find a secure way to have the rope run back and forth three times:

 :o  Because you live in a land where the supply of rope is unlimited, no doubt.

Quote
(The Zeppelin Bend .... it's easy to untie even when you don't want to untie it.

 ??? False, especially in the context of vehicle recovery where little to no loose flogging is expected.


Quote
Hunter's Bend is easy to untie

Very false.  That bend can jam badly with little effort.

We just had a thread where another poster re-confirmed this problem:
http://igkt.net/sm/index.php?topic=1832.0
« Last Edit: June 02, 2010, 12:26:23 AM by roo »
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jcsampson

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Re: best advice for towing
« Reply #22 on: June 03, 2010, 12:52:32 AM »
Since I recommended Hunter's Bend in this thread, specifically

http://igkt.net/sm/index.php?topic=1638.msg12511#msg12511,

and Hunter's Bend was derided as being prone to "jam," see

http://igkt.net/sm/index.php?topic=1832.msg12379#msg12379,

I will defend both myself and the knot:

Tie a single Overhand Knot in a single rope, tighten it, and try to untie it. THAT'S difficult to untie.

Take two ends of a rope, tie a Hunter's Bend, and try to untie it. Hold both tails at the front and, using the other hand, pull the side bumps down (one at a time) so that you can access the inside portions. Smile and think of me when you realize that it's not difficult to untie.

I've used Hunter's Bend for years in a variety of applications (using thin strings, too) and it has never been difficult to untie. Maybe I'm doing something wrong? Maybe I'm doing something right?

Think this, too: There are no memorable stories of the Bowline's having been responsible for breaking a rope in its long and safe application history. But, there they are, those who forever lament that the Bowline has a breaking strength of just 60%.

What's more important? A knot's application history or what happens in a lab? What happens in a lab can be useful, but it is merely a supplement to a knot's application history, which is much more important.

Look at the application history of the Reef Knot and--for the benefit of us all--never use it for anything but tying shoes, sweat pants, and perhaps the occasional Christmas bow.

Sure, Hunter's Bends may jam in labs, when tied using "thin stretchy cords" by those who might be intent on making them jam. But aside from that, Hunter's Bend has a satisfying application history.

Finally, I have noticed a distinct pattern: It is less often the case that a knot is one thing or the other and more often the case that a knotter just doesn't know a knot well enough in order to manipulate it to a satisfying degree.

I would rather enjoy the remaining useful properties of Hunter's Bend, than tie something else just to save twenty seconds when untying it.

JCS

roo

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Re: best advice for towing
« Reply #23 on: June 03, 2010, 03:25:37 PM »
I've used Hunter's Bend for years in a variety of applications (using thin strings, too) and it has never been difficult to untie. Maybe I'm doing something wrong?

I can guess, since I was just able to make 3/16 inch nylon rope jam with some relatively undemanding loading.  It will take much, much longer than 20 seconds to get it apart.  This was no exotic test with exotic materials.

Would you care to do a similar test?  Too many rope users don't realize how lightly they are actually straining their rope in their particular field of use, especially if they only apply puny human-arm-based loads.  Put the bend between two bars, and hold down one bar with your feet, while holding the other bar with your hands over your knees while seated and do a calf-raise exercise.  

Start with moderate loading, before moving up.  This progression of loading may save you from having to cut your knot free versus just taking 30 or 60 minutes to untie it.

P.S.  For even more dismaying results, repeat the tests with wet rope.
« Last Edit: June 03, 2010, 04:10:40 PM by roo »
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Dan_Lehman

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Re: best advice for towing
« Reply #24 on: June 03, 2010, 08:12:00 PM »
Tie a single Overhand Knot in a single rope, tighten it, and try to untie it. THAT'S difficult to untie.

Ha, let it be in 3/4" old nylon hawser that a trawler has lazily leaned
into for, oh, the past week / month / year !  Best hope is some soaking
of oil (vegetable) to gain slipperiness and then some iterative
efforts to work the knot loose, using pliers to grip & bend ... .
There is so little material from which to gain any contribution
to loosening (at the focus of your effort) in the minimal knot!
OTOH, there was some resistance to full collapse on its
tightening, the ends being pulled in opposition.  Eh ... .

Quote
Smile and think of me when you realize that it's not difficult to untie.

We can smile thinking of some of your assertions for other reasons.
Having invented this knot in 1973-4, I was taken by this apparent
quality, but then only used it in make-rope-use play for the excuse
of tying knots, largely.  Later, with e.g. 6mm climbing kernmantle
and a 2:1 or 5:1 pulley to put "real" force on the knot, I learned
otherwise.  I well know how to untie knots.  This one can jam.

So, to bring to light again a variation on SmitHunter's bend, I've just
"bumped" an old thread on interlocked-Overhand bends which shows
a few of them including the original and variation just discussed.

If the knot is left with large/loose collars, it might not jam, but then
it won't have the nice geometry of the snugger dressing either.

And then you also opined that Rosendahl's Zeppelin bend was prone
to untying:  that's something I think isn't really true.  It's looseness
might make it vulnerable to some snagging of its collars, and maybe
over some considerable time be more-loose than it was intended;
but in the context of having just been tied for a job, I see little risk
of any undesirable loosening.  (My keys have some thin binding cord
tied for ages, admittedly aided in this by the *blossom* of loose end
that is snug at the knot, acting a little like stoppers.)

Quote
Think this, too: There are no memorable stories of the Bowline's having been responsible for breaking a rope in its long and safe application history. But, there they are, those who forever lament that the Bowline has a breaking strength of just 60%.

True, that.  Some might count the presumed difference between some
cited strengths for the bowline vs. Fig.8 eyeknots as worth observing:
from D.Richards's data, it is over a half ton in half-inch low-elongation
nylon kernmantle, but 300# (about 10% of Bwl strength) in 10.5mm
dynamic rope, and less %-wise in nylon accessory kernmantle.  YMMV.
What's the probability that some loading will fall into just this difference?

Quote
It is less often the case that a knot is [claimed to be] one thing or the other and more often the case that a knotter just doesn't know a knot well enough in order to manipulate it to a satisfying degree.

Sometimes; sometimes it's a case of different opinions arising justifiably
from different circumstances (different conditions & materials).  Be assured
that Roo & I know well how to untie interlocked Overhands such as the
two cited by him.  (#1425 is rather different in this untying regard.)

Quote
Look at the application history of the Reef Knot and--for the benefit of us all--never use it for anything but tying shoes, sweat pants, and perhaps the occasional Christmas bow.

Sure, Hunter's Bends may jam in labs, when tied using "thin stretchy cords" by those who might be intent on making them jam. But aside from that, Hunter's Bend has a satisfying application history.

Frankly, I'd like to know what it is you're referring to for knowledge
of this "application history" ?  (I know that Ashley makes an assertion
re the SquaREef bend, but that's just that --his assertion-- , and I'm still
looking for the bodies.  Beyond that, the knot remained as a required
bend in one maritime organization (on a test:  rumor was that in practice
it was ignored).  Ashley's comment has been parroted ad infinitum, which
given the popularity and even official recommendation of the knot begs
for evidence of his worry!  Still, I'm happy to use other knots.

As for any such history for SmitHunter's bend ... ?  Huh?  I've never found
it "in the wild" -- have you?!

(Really surprising to me:  I've never found Ashley's Stopper (aka Oysterman's
Stopper
) in the wild, despite its being a quite simply tied knot with
good characteristics!?  I'd have thought that that would catch on.)

--dl*
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jcsampson

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Re: best advice for towing
« Reply #25 on: June 04, 2010, 12:03:48 AM »
Response to roo:

Does that represent one of your typical applications?

And why don't I find you arguing in defense of OTHER knot properties in addition to the property of ease of untying? Is that the ONLY property that matters to you?

Did you notice that, in

http://igkt.net/sm/index.php?topic=1638.msg12511#msg12511,

I said, "The Zeppelin Bend is another good choice . . ."?

Hmmm?

Now, what about all those other knots that are difficult to untie? They need to be EQUALLY disparaged, in all fairness. . . .

Response to Dan_Lehman:

It can be argued that each knotter will have a different set of needs and history of knot use obtained from fulfilling those needs. Most of what a knotter knows is likely to come from personal experiences. If everyone had the same history of knot use, knotting would be less interesting than it is.

In my personal history of knot use, the Reef Knot has let me down . . . almost every time I've used it, though it still manages to keep my sweat pants up. Good thing for that. I have heard bad words about the knot from a variety of sources, so I have an adequate consensus upon which to base my opinion of the knot. If I ever come across Ashley saying, "The Reef Knot is the best binding knot we have," my opinion of the knot will stay the same--and my opinion of Ashley will change.

It's a good knot to teach to show how knot designs can relate to each other (e.g., its conversion into a cow-hitch structure) and . . . what NOT to use and WHY.

Strangely enough, the "tightness" of Hunter's Bend pleases me.

I'm looking forward to tying/trying your SmitHunter Variation.

JCS

roo

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Re: best advice for towing
« Reply #26 on: June 04, 2010, 12:25:06 AM »
Response to roo:

Does that represent one of your typical applications?
Insofar as the test represents nylon rope under moderate strain, yes.

Quote
And why don't I find you arguing in defense of OTHER knot properties in addition to the property of ease of untying? Is that the ONLY property that matters to you?
We were discussing a specific erroneous statement that you made.  I stick to one topic at a time.  It makes it much easier to arrive at the truth.  You can start another thread if you'd like to ask about other knot properties.


Quote
Did you notice that, in

http://igkt.net/sm/index.php?topic=1638.msg12511#msg12511,

I said, "The Zeppelin Bend is another good choice . . ."?

Hmmm?
It happens to be irrelevant to the problematic statement(s) at hand.

Quote
Now, what about all those other knots that are difficult to untie? They need to be equally disparaged, in all fairness. . . .
Is this an admission that the Hunter Bend jams?  If you bring up other knots that are difficult to untie, I'd be happy to "disparage" them as well, especially if someone wrongly says that they are easy to untie.
« Last Edit: June 04, 2010, 04:15:38 PM by roo »
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jcsampson

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Re: best advice for towing
« Reply #27 on: June 04, 2010, 02:24:41 AM »
Response to roo:

I've still had an easy time untying Hunter's Bends in my applications; the applications have been numerous enough for me to feel very good about the use of Hunter's Bend, at least in the ways by which I have used it. The use that is recommended to Hereward in this thread is consistent with that use.

JCS

roo

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Re: best advice for towing
« Reply #28 on: June 04, 2010, 04:21:22 PM »
I've still had an easy time untying Hunter's Bends in my applications; the applications have been numerous enough for me to feel very good about the use of Hunter's Bend, at least in the ways by which I have used it.
So you're not going to do the suggested test to expand your horizons? 

Quote
The use that is recommended to Hereward in this thread is consistent with that use.

Even though you have no idea of the level of strain Hereward's unknown rope might see from unknown loading during vehicle recovery?
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jcsampson

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Re: best advice for towing
« Reply #29 on: June 05, 2010, 03:36:36 AM »
Response to roo:

I will likely (and eventually) do some tests like the one you spoke of in your post. One of the reasons for visiting this forum is to expose myself to the kinds of ideas that I normally wouldn't be exposed to. (I recall mentioning something previously about my admiration of "different perspectives.")

Quote from: roo
"Even though you have no idea of the level of strain Hereward's unknown rope might see from unknown loading during vehicle recovery?"

Well, the reason I'm not too worried about that is this: I suggested a three-coil-ring construct to wrap around the hardware. Such a construct remarkably reduces the burden that the knot in that construct will have to endure (which is precisely why the Fixed-Gripper Coil Binder works as well as it does) as well as the burden that each length of rope (of the six functioning lengths in that construct) will have to endure. . . .

I'll make a deal with you: You try the Fixed-Gripper Coil Binder and I'll try the Hunter's Bend Jam Test.  ;)

JCS