Dyneema topping lift failure

[sanibel sailor]

My Bristol 35.5 had a 1/8” stainless steel topping lift, fixed at the masthead and adjustable at the boom and when I bought her. The cable was deteriorated. I replaced it with a 1/8 inch dyneema line, same set up. This lasted about four or five years and then broke in the middle. I assumed it was too weak and had UV damage here in Florida. I replaced it with 3/16 inch dyneema, again single braid. Now four or five years later, this one has broken in the middle as well. Just sitting at the dock. It does not show any signs of chafe. I am considering going up in size and/or going with a covered dyneema line. Another alternative is a complete change of set up. I can rig an extra block for a topping lift at the masthead and bring it down to a cleat at the gooseneck. All my other lines are internal and run aft. Windage chafe and noise are disadvantages.

[Breaking Waves]

be interesting to see pictures - of where it broke.

Did you maintain it under significant load - cranked down? They do lose about 1/2 their strength within a year or two in that sort of UV. This UV strength loss happens even with braided covers - this has been proven in tests. You need a solid cover (like a plastic dip or heat shrink tubing) to get much uv protection on the core.

i'm surprised it broke in the middle (unless there was something was flicking it there). I guess it's possible that was sort sort of resonance/vibration point but a bit odd it would be same place for two different thickness.

[psk125]

Makes you wonder how long the deteriorated wire would have lasted. Replacing the dyneema for the third time, is the cost coming up to what new wire would have been at the outset? We're tempted to switch our ss wire backstay and running backs to dyneema for the weight savings when we race, but so far (since 1981) they show no signs of needing replacement.

[Breaking Waves]

we had dyneema check stays, same stays for 15 years. They were 10mm (bare), and they were not stored under significant load, but in use they were under significant load and did not break.

I test pulled one of them after 15 years and it was about 40% strength.

The UV resistance of bare dyneema differs significantly in its early years by brand. Some brands have more urathane coating on them, which provides some protection and others have almost none. After some years the difference between them declines as the coating wears off.

[DefinitelyMe]

Following. We have uncovered dyneema shrouds. Hoping to get ten years out of them.

I've had this sort of UV degradation with Spectra a few years back but not from dyneema yet. 3/16" does seem very light.

With regards to shrouds they say that when they get fuzzy it's a sign that they might be needing replacement soon. Presumably the fuzziness is caused by the outer layers breaking down in the sun but the inner layers should still be OK. Our shrouds are 11mm (7/16"). Does anyone know the penetration of UV into HDPE? At 3/16" it might penetrate right to the center, giving no signs of ageing before breaking. In that case going up a size or two would not only give you a greater percentage of strength to lose before it breaks but it might also slow the rate of UV degradation by protecting the inner layers better.

I'm just musing here, not suggesting anything in particular or claiming any great expertise on the topic!

[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.

[sanibel sailor]

Close up of breakage.
3/16" Breaking strength is reported at 5500 lb, almost double that of 1/8" (2900).
Should have been plenty without UV impact. I keep the mainsheet snug to prevent it from slatting when docked, but not cranked down.

[thinwater]

Originally Posted by sanibel sailor

Close up of breakage.
3/16" Breaking strength is reported at 5500 lb, almost double that of 1/8" (2900).
Should have been plenty without UV impact. I keep the mainsheet snug to prevent it from slatting when docked, but not cranked down.

Are you SURE these is not a sharp something or a fiberglass batten sticking out? More likely than any other reason.

[Sailmonkey]

Originally Posted by sanibel sailor

Close up of breakage.
3/16" Breaking strength is reported at 5500 lb, almost double that of 1/8" (2900).
Should have been plenty without UV impact. I keep the mainsheet snug to prevent it from slatting when docked, but not cranked down.

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

[Breaking Waves]

hmmm . . .its always hard with pictures, but away from the break the rope does not look totally cooked - its not super fuzzy and the color looks decent. This should have taken around (very very roughly) 2500 lbs load to break in the middle, on its own with no 'outside influence'. That's a possible load if you really really cranked it piano string tight - but I would have guessed unlikily (for reference that would be like a full on upwind totally cranked genoa sheet loading).

It's not a 'clean cut', rather damaged/broken over an area. In the close up, on the right strand it looks like there are two further areas which have been 'bruised' down below the break.

There is nothing that could be flipping/hitting it there - like the tail of a wire tie on the back stay, or a batten end fitting on the sail?

There is discoloration like something with a little rust on it, or something applying extra heat there.

1/8" was too small (after taking into consideration uv over time) but the 3/16 should have been about right.

IDK, odd.

[Breaking Waves]

Originally Posted by Sailmonkey

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

This is a much cleaner break than the op's. Probably a different cause.

But what diameter is that? It looks quite big for a 32' boat topping lift.

[Sailmonkey]

Originally Posted by Breaking Waves

This is a much cleaner break than the op's. Probably a different cause.

But what diameter is that? It looks quite big for a 32' boat topping lift.

It’s oversized because I use t he boom and mainsheet to lift the dinghy alongside at night.

I want to say it’s 1/4” but can’t remember what I’ve bought to replace it. Also too lazy to go below and get the calipers to measure it.

[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.

[sanibel sailor]

Original color was bright orange.
I keep the boom off center when docked, so unlikely to chafe on backstay. When sailing, TL is a bit slack. Battens insert at forward end of sail. Boat has not been underway in 6 weeks, on a dock in a narrow river without any waves and minimal wake. No weather of significance recently.
Same circumstances with my initial line. I just came to the slip one day and boom was in the cockpit.


I rather suspect low quality line with insufficient UV protection.


With what should I replace it? SS wire, covered high-tech stuff, better/bigger Dyneema?

[Breaking Waves]

If it were me, i'd go back to wire., since we don't know the cause of the failure. Something is going on with the 2 failures.

What was the brand of the line? I remember there was a samson amsteel 'knock off' which was super poor quality.