Jan 12, 2012 at 1:09 pm #1284069
The photos below show 50# test kite line with a very light tension bead for adjusting the line.
Eighty of these beads, weigh about 1 ounce. You can buy them, and line, at kitebuilder:
A bead plus 3 feet of line weigh about .7 grams. So you could add 6 such sets to a tarp for a total weight of about 4.2 grams or about 1/7 of an ounce total.
The bead is just big enough to operate with gloved hands. It is about 3/4" long and thicker at the middle. This really helps when grasping it and moving it up or down the line. There is just enough friction to hold the bead in place, even when not under tension. So the line stays as it was last adjusted unless something pulls firmly on it.
They also sell a larger bead which uses line up to 100 lbs.Jan 12, 2012 at 10:41 pm #1824126
Those are pretty awesome, what with the light weight.
The kite sites are full of great stuff – glad you found this item.
Have never liked the other tighteners, but this one looks like it could spell the end of the tautline hitch.
Can see there definitely is no significant weight penalty, thanks to the specs you provided.
Now to find the right spectra/dyneema cord. Will get some and experiment.Jan 12, 2012 at 11:14 pm #1824136
@rcaffinLocale: Wollemi & Kosciusko NPs, Europe
> Now to find the right spectra/dyneema cord.
Back to the kite shop!
CheersJan 13, 2012 at 1:09 am #1824150
@stingray4540Locale: South Bay
50# test? Is that strong enough for tarps/tent flies? Seems the standard spectra and dyneema cords being used are 200+#.Jan 13, 2012 at 7:33 am #1824206
John S.BPL Member
Thanks Daryl. What exact line are you using? The Black Death line?
We also need to find out what line thickness is TOO thick to be used with these tensioners?Jan 13, 2012 at 8:24 am #1824221
@cwayman1Locale: East Tennessee, US
"Seems the standard spectra and dyneema cords being used are 200+#."
I believe that the current spectra/ dyneema cords are used more for their light weights rather than their tensile strength. i.e. Bear-bagging cords (1-2oz/50-100ft) may be able to hold 200+lbs but will probably never have to.
My question is: will tarp tie-outs ever exceed either 50 or 100 lbs of tension under typical use (excluding extreme alpine storm settings, above treeline 100+mph gusts, etc)? I'm sure that there's a BPL article somewhere on that.
Anyway, cool find Daryl!Jan 13, 2012 at 9:10 am #1824236
<del></del>Jan 13, 2012 at 10:01 am #1824257
Yes, the line is the Black Death sold at Kitebuilder. 50# test line is the largest diameter that will fit these beads. The larger white bead they sell will take 100# test.
50# test is pretty low, for sure. I think it would match nicely with a .33 ounce cuben fiber tarp, however. Steve Evans tested the reinforcement patches on a tarp of that weight and found they tore at 80 lbs, if I recall correctly. So, theoretically, the line would break first. That's good. Easier to replace the line in the field than the torn patch. These things are definitely not to be used for a big circus tent.
No need to test the cord with my patent pending* drop bucket testor because it is already rated (50#) by people smarter than me. The beads are not rated, however, so I may return to the lab just for the fun of it.
(1) I've also used this system on my lightweight backpack frame. I can adjust tension and take things apart easily. Been using the larger beads because the smaller ones were out of stock but smaller ones should work too.
(2) Threading the beads should be done at home, not in the field. It is easy to do once you get the hang of it but it requires a floss threader, good light and good eyes.Jan 13, 2012 at 11:42 am #1824310
My staff completed the static (bucket hung carefully/no dropping)load bearing tests of the bead and 50# Black Death line assembly. Lab results were as follows:
The line and bead did not break while supporting a bucket with a jack, wrench and some fishing weights in it for a total of 22 lbs.
The line broke with a bucket weight of 26 lbs. Bead held.
Tested the line without the bead and it still broke with a load of 26 lbs.
So much for the 50lb test rating. Perhaps I'm misreading the term "50 lb". Maybe it means a certain length weighs 50 lbs. Don't know but this line couldn't lift 50# on its best day at the gym.
DarylJan 13, 2012 at 2:48 pm #1824415
David ThomasBPL Member
@davidinkenaiLocale: North Woods. Far North.
Most knots and methods of attachments reduce line strength by about 50% which is exactly what you saw. When the line makes a turn, the outer fibers are more stressed, fail first, and then the inner fibers fail.
Try wrapping the line around a moderate diameter rod or spool (1" diameter for small line like that) and you'll likely test it to spec or a bit more.
Look up a references on knot strength and consider different knots if you want more strength. But it's hard – our common knots, again, reduce line strength to about half. Or consider different attachment methods – gluing to fabric, weaving/splicing in more strands (boy, that would be tedious! It's been years since I did long splices even on laid rope), or get a couple of larger-diameter wraps around something before tying off the line.
Editted to add: fishermen have these same concerns and work in the small very small lines. Check fishing info for recommended knots.
Thanks for the testing – always a good reminder of these pesky, practical concerns!Jan 13, 2012 at 3:29 pm #1824437
I did several tests. The line always broke in an open, single stranded, unknotted portion of the line with nothing near the break location.
As a practical test I think it was good for my intended purposes. I had things set up pretty close to the way I'd use it in the field.
DarylJan 13, 2012 at 4:36 pm #1824455
David ThomasBPL Member
@davidinkenaiLocale: North Woods. Far North.
Okay, then. I retract what I said. I've always had bigger lines break at the knots, but I haven't tested really small stuff to failure.
Thanks for the info – that's good to know.
I've been packing little hanks of 80- and 100-pound test braided fishing line (big fish up here) in my fix-it bag with a mini-bic, wax paper, folded Al foil, etc, it always with me. Emergency shoelaces, repairs, etc. Last I used the line was when I totally spaced on the need for Croakies on a 2-week private Grand Canyon River rafting trip (duh!) and tied one out of that line on my first day on the River.Jan 13, 2012 at 6:19 pm #1824487
Well, the other kite shop, anyway.
Kitebuilder is out of stock of spectra line.
Goodwinds has a variety of them:
Now to try to find out what weight will fit the bead tensioners without wasting $.
Do you sometimes feel like a rat poking through a maze?
BTW, Goodwinds ships much faster.Jan 13, 2012 at 6:36 pm #1824493
I also broke the small beads in a couple of the tests. The Black Death kite line broke at the same time so I couldn't pinpoint the breaking point of the small black beads. Looks like it is somewhere between 26 and 40 lbs.
DarylJan 14, 2012 at 6:37 pm #1824838
Ah, now you tell us.
Methinks we will be using the larger size tighteners.
Still, they look like a step ahead of the hitches, due to the advantages you posted.
Will try just a few first, with some spectra cord.
Don't see the need for scientific tests – if I pull hard and the tightener holds, that will be enough.
Don't want to get too tied up with this stuff.Jan 14, 2012 at 7:57 pm #1824884
"Don't want to get too tied up with this stuff."
Nice pun.Jan 14, 2012 at 8:29 pm #1824891
OK, been giving this some thought.
The 50 lb test kite string broke at 26 lbs static load. The bead broke at some undetermined load above 26 lbs so, without further testing, I'd assume a breaking point of 26 pounds for the bead too.
To allow for a margin of error I think I wouldn't count on this system for a load that exceeds 15-20 pounds.
I definitely do not recommend this as a replacement for biners and climbing rope.Jan 15, 2012 at 3:09 am #1824936
John S.BPL Member
That bead must be made of crappy plastic and not ABS plastic.Jan 15, 2012 at 4:35 am #1824940
James MarcoBPL Member
@jamesdmarcoLocale: Finger Lakes
If you must use adjusters, I have found a few, abiet a very few, instances where a good adjuster would be better than a removable double overhand knot, These could easily be made. Hey, Mr. Lawton, you listening?? A drill press and a simple jig are all that is really needed for this, sandpaper, or perhaps some sort of flame polishing to remove any sharp edges. Maybe a needle file?
Fine fishing line is OK for guy lines. I agree with David about the multiple use of that stuff. That said, I do not use it for bear line. It cuts into bark or wood and can hang up trying to retrieve a bear bag. 1.5mm is better for 10-12pounds of food.
Braided fishing line works well. Fly line backing even comes in Spectra and coated. 40pound is a real 40pound test, not 26pound. It is, however, quite slick. Many knots do not care to lock into it well, soo, I use fishermens knots, double overhand knots for loops, melted ends, and loop-to-loop connections. A bit of a pain to set up, but relativly permanent.
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