Dyneema topping lift failure

[thinwater]

What's odd is breaking in the middle. Even with a good splice, it is a little weaker there. I've broken many in testing, and they nearly always break at the tail of the splice. This must be something.


Another factor could be snatch-type impact at some point that you are not aware of. Perhaps introducing a 6-foot polyester tail would reduce this peak force.


I have avoided Dyneema TLs because of concerns of this sort. In fact, I want a little stretch. I've never had one fail in less than 15 years, and they were PDB, typically weaker then what you broke. Actually, I've never had one fail (I replaced them).


You say "low quality"; what brand and model?

[JPA Cate]

Since you're planning on an extended cruise, I, too would go back to s/s, as Breaking Waves said, if you cannot find a chafe culprit on your sail or backstay. The reason is to avoid the broken topping lift during a squall, when you've got the boom topped up for the reef in the main.

If there is a chafe area on the main, put some sticky-back sail cloth up there, sacrificially, and renew it as needed. [There are also spectra sticky-back chafe patches.] I would suggest a high visibility color to catch one's eye in grey weather. Just to help be seen. The human eye is attracted to color in motion, so it will help watch keepers see you.

That said, you might be okay with covered dyneema, but it does require renewing what is frequently to me. Ev. 4 yrs? Grump.

Ann

[sanibel sailor]

I have been mostly racing and daysailing and rarely need to reef. With an extended cruise planned (once this little Covid nuisance quiets down), I am rethinking the end of boom adjustment. Fitting a block up top would double my weight/stretch/windage/cost, but give me some flexibility and serve potentially as a spare main halyard. I could still retain the end of boom adjustment gear to give that option when needed.

[s/v Jedi]

I would be very suspicious of the brand name of that Dyneema (and Spectra is Dyneema, isn’t it?)

We have 3/8” Samson Amsteel Blue running backstays which are from 2005 and still going strong. I believe the coating is key in UV prevention, as is the diameter (thicker diameter only gets UV damage on the outside).

We have halyards that are 1/4” Amsteel Blue. Oldest one is 3 years old I think, looks great, no fuzzies.

[charliehows]

Interesting discussion; the conclusion I'm drawing is that good quality 16 braid and spectra/dyneema have similiar levels of longevity and that neither come anywhere near outperforming or even matching steel rope, either stainless or gal. I'd mark any boat I was considering buying with any rope rigging ie;stays/shrouds, as requiring immediate full re-rig with wire and adjust any offer downward accordingly.

[sanibel sailor]

I tested the line by tying it between my wife’s F250 and my old 1000cc Honda Insight. Gentle tug snapped it in midsubstance, not where it was tied over sharp edge of steel bar. No prior signs of significant chafe where it broke.

Pulled the tail out of the splice. The tail had lost its color almost all the way down the taper. Confirmed for me at least this is a UV problem. I do not recall the brand of line. The first smaller one was Robline. Second might have been unbranded knockoff. I am thinking I will switch to 1/4” T900 or similar, running to base of mast.

[Orion Jim]

I’ve had an AmSteel-Blue silver/grey topping lift (3/16”) for several years. I also have a set of lazy jacks out of the same stuff. I’ve replaced the topping lift once after seven years because I could see “hairs” in bright sunshine. There was no localized chafe but I figured the hairs were an indication that it’s service life was nearing an end. I think it’s perfect for the applications I have chosen for it but vigilance is always required.

[roverhi]

Have a 1/8th inch topping lift on my Pearson 35 that's going on 11 years mostly in Hawaii and showing little signs of deterioration. It's a long boom so is holding up considerable without a problem. Only complaint is the 1/8" line sings if the wind is above 10k which fortunately not a problem in Kona. I'm going to replace it this year simply out of principle.

[UFO]

Slightly off topic, but how often should soft shackles be replaced?



Its pretty sunny here in Perth and never thought too much about the sun degradation

[JC Reefer]

Originally Posted by sanibel sailor

I am thinking I will switch to 1/4” T900 or similar, running to base of mast.

Interesting topic. Spectra (Amstel) is fairly UV stable and should hold a lot better then older formulas like technora (T900). I don’t have the numbers in front on me now but I call it being expected to last multiple times longer when exposed to direct sun.

I’m sure many have seen old technora cored lines where the core splits and the jacket stays intact.

Not discounting the UV as it degrades everything. But why would the breaks be in the middle. I wonder if the wind movement adds to the issue. Maybe the individual braids move and rub against each other in that section of the line.

[Simi 60]

Originally Posted by Sailmonkey

Our spectra topping had the exact same break at the 8 year mark!!

In fact, I still use the line for lashing odds and ends. Here’s a photo of one half of the break

Attachment 224184

Looks identical to the break we had on 8mm holding up a 300kg tender.

Still use the broken for lashing non critical things

[DefinitelyMe]

Originally Posted by charliehows

Interesting discussion; the conclusion I'm drawing is that good quality 16 braid and spectra/dyneema have similiar levels of longevity and that neither come anywhere near outperforming or even matching steel rope, either stainless or gal. I'd mark any boat I was considering buying with any rope rigging ie;stays/shrouds, as requiring immediate full re-rig with wire and adjust any offer downward accordingly.

I think that's an unfair conclusion to draw from a not-particularly-thorough discussion on the topic.

Each to his or her own. For my part I will never rig one of my boats with stainless rigging ever again. Dyneema wins hands-down until something better comes along.

[wingssail]

Originally Posted by Breaking Waves

That line is huge strength. Even after uv damage it did not break under topping lift or dinghy lift loads. And it is quite clean (except for the two distinctive last strands which finally gave under load). Something chafed/cut/heated it up in a quite narrow zone. I guess probably in a relatively short time frame or you would have noticed it.

I will comment in any case . . . . wire can chafe the leach of your mainsail, but it is rather less susceptible from breaking in this way. You just have to choose your poison.

This brings to mind the failure of my dyneema jib halyard. 6mm dyneema, (uncovered) similar to all of my new running rigging (and lifelines). Within one year the jib halyard just failed. The break looks quite simile to the breaks shown by the OP. None of my other lines broke.

This concerns me. A halyard breaking is not too much of a big deal (other than the cost). We just rig a new halyard. But if a lifeline breaks we cold lose crew over the side. THAT is a big deal.

Then there is the concern about going aloft on a halyard. For many years we used one halyard to go aloft (when they were all wire). I know that you should have two halyards, in case one breaks, but with only one person to help me go up, that wasn't too easy.

But if I cannot trust the dyneema, then I just don't want to take a chance without a safety halyard.

I wonder if there is something going on with dyneema which results in these sudden failures.

[s/v Jedi]

Yes, I believe that these failures are not from genuine Dyneema made by DSM. They must be a poor quality knock off product.

The most widely available good Dyneema is Samson Amsteel Blue. The only failures I know of are during destruction testing. I don’t understand how people expect equal performance from no-name or off-brand products... they cost so much less for a reason!

[Benz]

Originally Posted by sanibel sailor

Less sail chafe was a bigger driver to my decision than cost of stainless.

The upper splice is cowhitched over a Clevis pin and shielded inside the masthead assembly. It has retained its original color. Thimble lower end at the adjustment tackle. Break is about 15 feet above boom, length is 42 feet.

So now instead of the wire chafing the sail, the sail is chafing the dyneema. But there IS a chafe point, or you wouldn't have wanted to switch. 3/16" dyneema is pretty cheap: why not buy a new piece and slip a yard or so of dyneema anti-chafe sleeve along to the spot where the lifts keep breaking and seize it in place? Inspect it every year or so, replace as needed.
Everything on my boat has a service life, and I expect to replace everything eventually, except the hull and ballast, if I live long enough. Getting five years out of 3/16" dyneema in the sun is a quite good replacement interval, IMO.