Synthetic fibres -- objective performance ratings?

[Bob Pingel]

The figure 8 follow through was described as "ideal to attach two pieces of rope together" and was tested in that way. The testing machine had the belay points where you could "wind the rope around a drum and secure with a cleat".

I have had a few splices destructively tested, and they break right at the end of the taper. My understanding is that this from the stress riser due to the splice. They have all broken above the rated tensile of the rope itself, implying we did not know the true tensile before we started.

My view is that if we can splice to rated tensile (and manufacturers deliver rope at or above what they rate) and use a healthy safety factor -- I typically use at least 3:1 for running rigging -- we will keep rigs up and people happy and healthy. I suppose the ideal would be to break a section of rope off of every spool, but this gets expensive and I think the samples could vary as you work through the spool. I feel pretty good using these guidelines and then breaking a splice here and there to keep myself honest.

Bob

[SV Papillon]

Bob,

If you have the ability to test a splice??? I would very much like to see how a tucked 12 strand spectra splice fairs. I don't know the correct name but it was the one I learned working on deck on fishing boats in AK and what I have used since. Essentially divide strands into two groups of six. Put one group through the core at the eye size. In pairs tuck strands down a parallel set of strands placing the tail of the previous under the one you are tucking. Tapering out at the end.
It seems keeping tension uniform is crucial to it coming out neat, not too much or too little. We use this splice on the boat I work on for winch hook etc with pretty severe usage and loading. Lines from 5/16" to 2". If the line comes from a supplier already splice it typically has the Brummel splice?? tucked back into the core.
Anyway just curious to know how the splice would hold up.

Thanks

Jake

[Bob Pingel]

I do not have the ability to test splices myself, I have had mine broken at both Yale Cordage and New England Ropes.

I have used a tuck splice on single braid dacron -- megabraid or alike. I did six or eight tucks, how many tucks do you take in high mod?

I am guessing that the splice techniques differ in larger sizes of high mod ( I have never used over 3/8"). For instance, if we used Brion's brummel splice on 2" spectra, the bury would be 16 feet long!

Bob

[SV Papillon]

The splice is indeed long about 6' I'm guessing not 16' though. Not sure exactly what the one they are sent up with is. These are Gilson lines used to hual the fish on deck approx 60 ton winch pulling over a midship gantry arch and reaching to the stern. I migrated to the much warmer engine room a while back so I just go up for fun and to bug the bosun now.

One of the reasons I liked the tucked splice is it had less waste. An issue if I'm buying the line or just don't have much. I usually do about 8-15 tucks about 4" on 1/4" and 5/16", 6" on 3/8" and 1/2"
It would probably hold with less but thats what I have been doing. I use a little Swedish fid.
and must admit I like doing them they look so neat when you are done especially the small stuff.

I think I have one in the shop maybe I'll take a pic and post it tomorrow.

Jake

[Dan Lehman]

Originally Posted by Bob Pingel

The figure 8 follow through was described as "ideal to attach two pieces of rope together" and was tested in that way.

Oh, thanks again, for that--in my hasty review of it ($5 is more than I want to toss
for it), I missed that point. From the knot pictured ruptured, they used what I call
the "perfect form" in "weak" loading--the inner twin taking the load instead of the
one reaching to the very end of the knot (along the axis of tension).

Results given for knots resp. in Dbl.braid Nylon, Sta-Set, Endura Braid

Cowboy Bowline: 55% 55% 38%

Clove & 2HH: 65% 63% 36% (looked to be maybe on 2" dia metal?)

RT & 2HH: {slipped @40%(5,148#)} {slipped @63%(6,492)} {slipped @29%(6,166#)}

Fig.8 BEND: 57% 52% 37%

Grapevine Bend: 54% 51% 30%

I'm REALLY surprised at the figures for the Grapevine bend!?
Too bad they didn't bother to stopper the RT&2HH (or make it 3HH) and check its
strength--or try the Anchor bend.
And with the hitches, there's a question about relative diameter of the hitched
object: some hitches will work well as ring hitches but not so well on spar-
or pile-sized objects. Note that the two polyester-sheathed ropes slipped nearly
at the same absolute load--which makes sense, if they're relatively similar in
flexibility/compressibility; the nylon, sooner.

rate of pull: 1 foot / minute

(They mention the hi-mod cordage being stronger than steel pound for pound:
heck, way stronger; sometimes as strong per diameter!)

--dl*
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[Renoir]

I am disappointed that the carrick bend did not get evaluated as it is perhaps the strongest bend to use when attaching lines together and I have used it many times without failure. This bend is easy to tie and easy to break loose even after a really strong pull and shock load.

To be sure this bend is not to be trusted below water if it will be pulled and loosened and banged around without first fastening the bittern ends to the working parts, a minor inconvenience when considering that if one must join two lines together without splicing when needing maximum strength.

[Dan Lehman]

Originally Posted by Renoir

I am disappointed that the carrick bend did not get evaluated as it is perhaps the strongest bend to use when attaching lines together and I have used it many times without failure. This bend is easy to tie and easy to break loose even after a really strong pull and shock load.

How did you come to this assertion?
Most tests would show the Grapevine to be much stronger. (Hence my surprise at SAIL's.)
The Carrick is used/favored, so I hear, in the hard-laid (read STIFF) ropes used for the
big crab pots (6-800# empty!) out from Alaska; I think that Rosendahl's bend would make
a good candidate for that, too.
For Carrick-like performance (but stronger, I'd think, a little), try Ashley's bend #1425 or
1452--this latter being much more secure when slack.

--dl*
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[Justaddwata]

My disappointment at the Sail test was that they failed to reference the pin diameter. The larger the diameter of the pin the greater the load on the knot. Also the diameter of the eye formed (by knot or splice) is also important info for reference.

I worked with Brion some time ago when he was reviewing knots in HM ropes. He did a write up on the subject also.

Back to the original topic of the thread. Comparison tests are only as good as the test method used. Repeatability and consistancy of the aparatus and method is the only way to make a test that yeilds usable data. There are so many ropes, tests, reviews, experts, and final applications that it is a daunting task to consider. I have seen several good abrasion test methods and know NER had done some work with these methods in evaluating chafe of mooring pennants.

The use of PBO in jackets is for its resistance to extreme heat and abrasion. The fact that its life is not much longer than that of milk when in the sun seems of little consequence to those with big budgets and high expectations.

When it comes to bears chewing through Vectran Vs Spectra - you may want to consider if this is abrasion or shear. Spectra is certainly superior in cut resistance - but that is not abrasion. My experience has been that Spectra and Vectran are comaprable in an abrasive environment. I have never done an apples to apples test to distruction of both Spectra and vectran. Spectra will certainly have an advantage with how slick a surface it is. But again - with the testing. You would have to consider under what load such abrasion would be occurring, what braid is used for each, How rough a surface etc.

I am interested in seeing more testing. Strength loss over varying radius. Tensile breaks at varying travel rates. Abrasion of different fiber types, different braid types, different loads, different abrasive surfaces. UV Degridation. Shock loading. and so on.

[Renoir]

Sorry Dan, I should have qualified further the reasons for my liking the Carrick bend. This bend is easy to tie, easy to untie and strong and can be used with widly varrying diameters and types of line mixed.

The bends that you mentioned are qualified by their being confined to using lines of fairly equal diameters. The Grapevine can be a bitch to untie after it has been subjected to a heavy pull in water. I do like the symmetry, however, of those that you mentioned. I truly don't know how to choose between an Ashley #1425 and the Zeppelin or Rosendahl's bend....any suggestions?
Thanks

[Dan Lehman]

Originally Posted by Renoir

Sorry Dan, I should have qualified further the reasons for my liking the Carrick bend. This bend is easy to tie, easy to untie and strong and can be used with widly varrying diameters and types of line mixed.

The bends that you mentioned are qualified by their being confined to using lines of fairly equal diameters. The Grapevine can be a bitch to untie after it has been subjected to a heavy pull in water. I do like the symmetry, however, of those that you mentioned. I truly don't know how to choose between an Ashley #1425 and the Zeppelin or Rosendahl's bend....any suggestions?
Thanks

I've seen another way, but I tie the Carrick in the capsize-the-lattice-form way,
and with different rope types, that will be somewhat tricky. I got my numbers backwards
or my "former" lattered, but #1452--what Day got started as "Ashley's Bend"--is quite
like the Carrick but for being stronger (in some misc. testing), and more secure; it has
a few ways of being dressed/oriented, though. (Another interlocked-Overhands bend,
called "Shakehands" by Harry Asher, and now in some knots books, can similarly be
seen as a derivative of the Carrick.) #1425 can also handle mismatched ropes within
as much range or more than I'd think a Carrick could.
Rosendahl's bend presents two broad, flattish faces, with ends coming out on small
sides to these, so to speak: makes for taking knocking about abrasion pretty well.

Whizz-bang tying methods have been invented for both 1452 & Rosendahl's, both of
which impress me as too clever by half--one must mind picky details in order to get
the final effect; I much prefer to form one Overhand in rope, and then choose how the
2nd gets formed into it (to make 1408 or 1452 or 1425 or ... or Rosendahl's or ... ).

Again, on the strength of the Carrick, I've not seen much testing--just a lot of echoes
of the rumor (Ashley's?); it does not LOOK so strong to my eye, in terms of material
curves (part of the picture).

--dl*
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