Load Testing Results

[thinwater]

^^ Drew

[JPA Cate]

Ooops,

Sorry about getting your name wrong, Drew. When I'm done blushing, I'd like to say thank you again. ;-)

Ann

[Jim Cate]

More good stuff from our valiant testers! For either one: when making a simple bury eye splice in D-75, Samson recommends putting a few stitches through the bury area to prevent slippage when lightly loaded. I'm wondering if the stitches have any effect upon strength? (None of the ones that I have in service have either slipped or failed, but I doubt if I have come near ultimate loading).

Thanks again, both of you!

Jim

[estarzinger]

Originally Posted by Jim Cate

More good stuff from our valiant testers! For either one: when making a simple bury eye splice in D-75, Samson recommends putting a few stitches through the bury area to prevent slippage when lightly loaded. I'm wondering if the stitches have any effect upon strength? (None of the ones that I have in service have either slipped or failed, but I doubt if I have come near ultimate loading).

Thanks again, both of you!

Jim

I have been told that sort of light stitching has a very small negative effect on strength, but that it is practically speaking unmeasurable because the failure will almost always be at the end of the bury taper, and the taper variability will completely swamp the stitching effect.

[estarzinger]

I was working a bit on 'bar tacking' . . .below is a photo.

On the right is the single pass zigzag. That's 16 stitches in 5/8", or about 25/in. The sailrite seems to do this pretty cleanly and consistently (V92 thread).

And on the right is what it looks like after 3 passes. I should try to get the ends a bit closer to the webbing edge.

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[estarzinger]

I just tested 3 dyneema lashings, in three sizes of line. I was curious how secure the half hitches are to finish the lashing, and where they would break.

In the smaller two lines, two half hitches held, and the lashing broke at the pin bend area.

In the larger line, two half hitches slipped slowly, but three held, and it broke where the lashing was 'clamped' by the half hitch.

So . . .3 conclusions . . . the half hitches are more secure (under static loads) than we might have expected. My suggestion in the life line work that 4 is a satisfactory minimum is probably correct (particularly if they are taped or sewn in place). and all three samples broke at 'about' 50% (51%, 49% and 41%) of 6x (for three loops) the line strength.

[thinwater]

After thinking through the challenges stretch caused for webbing, I decided to further investgate stitching of nylon rope ,specifically dynamic climbing rope. Designed to elongate nearly 100% before break, it can do some terrible things with stitching.

I broke 6 dog bones learning what follows.

First, you can use much heavier thread than in webbing--100# is fine and will break without damaging the rope. Second, with proper stitch patterns it is simple to fit about 60 passes of 100# thread into the first inch of a 7/16-inch line. Enoughto break the line without damaging the line.

As for seizing, don't even try it on nylon. At full load the diameter is only 65% of what you started with--it will be loose by 20% load and slip.

However, dynamic rope holds many knots at 75_85%. A knot may well be smarter in most applications. Yes dynamic rope can be spliced--mostriggrers will refuse.

----------

Why the interest in dynamic rope?
A. Like Estar, I use dynamic rope for the traveler. Very smooth jibing and not mushy to trim.
B. I use dynamic tethers. A much softer catch
C. It was simply a logical extension of stitching polyester, which has many practical applications. Lessons learned will make polyester splices better.

[estarzinger]

Interesting. It is too bad Tenara does not seem to sell a stronger thread - if they did it would eliminate the UV weakness of sewn splices. Is there an easy 'paint on' protection (like that "whip it" plastic dip) that would give near 100% UV protection (and perhaps a little chafe protection also)?

When I get my 5,300lbs webbing I am going to to do a quick study of what sort of pattern will in fact hold +4,500lbs. It seems pretty easy to get to around 2000lbs, but will take the "better" patterns to get to 4,500.

[thinwater]

Actually, I am starting some long-term testing of both splices and UV/chafe protection options. Liquids like Rope-dip and Maxijacket will be one part, as well as physical coverings like tape, webbing, and heavy duty heat-shrink (commonly used on commercial sewn splices). Some on the boat, some in the sun on a rack. In a few years I'll start breaking them at timed intervals.

[Stumble]

Originally Posted by estarzinger

Interesting. It is too bad Tenara does not seem to sell a stronger thread - if they did it would eliminate the UV weakness of sewn splices. Is there an easy 'paint on' protection (like that "whip it" plastic dip) that would give near 100% UV protection (and perhaps a little chafe protection also)?

When I get my 5,300lbs webbing I am going to to do a quick study of what sort of pattern will in fact hold +4,500lbs. It seems pretty easy to get to around 2000lbs, but will take the "better" patterns to get to 4,500.

How about trying to sew it with dyneema fishing line? I use a lot of 75lbs test instead of whipping twine but I also only do hand sewing so I have no idea how it would work in a machine.



I was wondering if you have tested any loups? I use them a decent bit for quick attachments of gear, and as extenders from time to time. I would be interested in seeing how they handle destruction tests.

If you are interested I would be happy to make a number up and send them to you when I get back in the country.

[Cuttyhunk]

Originally Posted by estarzinger

I am looking for some 4,500lb (that's the jackline reg minimum) 1" polyester webbing . . . anyone have a good source? None of my usual places seem to carry it. I can find nylon, but not polyester?

Uscargocontrol.com

I just bought some for my boat cover project.

[thinwater]

I'm an idiot.

I knew this about thread. All of you knew this. But in case you don't and in case anything I posted was based upon whipping twine numbers...

Thread companies all do their own thing with strength and numbers, at least often enough that you must beware.

Marlow whipping twines and Robline whipping twines are numbered completely differently. I didn't realize this because I was working off monster spools and had not needed to buy in many years. Even West Marine is confused; they switched from Marlow to Robline and the labeling is all screwed up.

I did strength test all of my twine, so the number are not affected. But if any of my posts referred to twine numbers, I may have screwed some of the posts. I just tested a bunch of samples, and it goes like this:

Robline #4 0.4mm 10 pounds

Robline #6 0.6mm 21 pounds

Robline #8 0.8mm 50 pounds

Robline #10 1.0 mm 90 pounds

Robline #15 1.5 mm 180 pounds

For webbing, all of my testing was with doubled #8 twine (50 pounds).

For rope I have used both doubled #8 (5/16-inch and below) and doubled #10 (3/8-inch and 7/16-inch). I use #15 for 1/2-inch rope, but I haven't been testing that because I can break it.

Rope companies tell you how big and how strong. Why do thread companies think this is a game?

FYI, if you want to measure thread or twine, wrap it around a pencil and count the turns. You'll get close.

[Seaworthy Lass]

Evans, do you have the time to test one more knot?

We still don't have a good option if Dyneema needs to be tied to anything else (the Palomar and Estar only held to about 54% of line strength).

The reported usefulness of the Triple Fishermans as a bend in Dyneema makes me wonder how effective half of a Triple Fishermans would be (it is a noose type knot so maybe a larger pin size is needed). I not sure what this knot is called.

The photo is how it would be tied (I wind the loose end around my finger so that when my finger is removed there is a nice gap produced so that the loose end can be easily poked through for the final step). I think for added strength this should be gradually tightened up by hand as shown.

Any chance of testing this out please?

[StuM]

> I not sure what this knot is called.

(Multiple) Scaffold knot or triple overhand noose ABOK #1120

[Seaworthy Lass]

Originally Posted by StuM

(Multiple) Scaffold knot or triple overhand noose ABOK #1120

Yes, that's it thanks .