Dyneema lifelines

[slug]

Lab test

https://dynamica-ropes.com/wp-conten...SM-Dyneema.pdf

[slug]

For other readers interested in dyneema , the numbers for Uv burn are even greater than the lab results

When the outer layer of dyneema UV burns it forms a protective cover that provides some protection to the interior fibers

Unfortunately when you chafe this outer , burnt layer , off ...you then expose fresh dyneema to the elements

On the mega yachts I have seen high load dyneema strops and pennants brought into the shop and break tested

The results are not good

It is possible to paint a special UV coating onto the fibers to extend service life

It is not chafe resistant

[pilott]

I have what may be a daft question. Would it be ok to use , say, 1/4" dyneema lifelines, covered with pex tubing to give uv & chafe protection, and better feell?

[Jim Cate]

I can see the logic of the diameter affecting the rate of strength loss from UV. However, if you look at the results from both your new source and your old source which I quoted for 8 mm line, they are quite similar... and again, 8 mm is what I have used and what others report using.

Now, saying "the results were not good" isn't very convincing without some data. Where is it?

And you keep saying that it isn't chafe resistant... the following is from your first linked report from US Sailing:

"This fiber has very attractive properties: extremely strong (15 times stronger than steel fiber of the same weight) and low stretch for its weight, resistant to flex fatigue (Relative Flexlife: Dyneema® 100, Vectran 55, Aramid 8, stainless steel fiber 6), extreme chafe resistance (8 times lower dry abrasion and 40 times lower wet abrasion than all other conventional fibers) and quite UV resistant."

What's a poor yottie to believe... your unsupported statements or the published report from US Sailing?

Empirical data, as in increasingly common successful usage by cruising yachts shows dyneema to be a viable replacement for s/s wire in lifelines.

Jim

[slug]

Originally Posted by pilott

I have what may be a daft question. Would it be ok to use , say, 1/4" dyneema lifelines, covered with pex tubing to give uv & chafe protection, and better feell?

Many times protective covers are used for chafe and UV protection

I don’t know the cover material. It a rather hard , stiff textile

A piece of pipe may work

Many things may work .

[s/v Jedi]

How much irrelevant information is in this thread is crazy, so let me add some points for thought:

- Dyneema is a Dutch invention and produced by DSM in the Netherlands. Some companies have a license to produce it as well. Only these official sources of the fiber should be considered, because it is as much about things like quality control, consistency etc. than it is about the molecular structure of the fiber (plenty inferior knock-offs). Stop talking about any products of which it is not clear what is is or that are knock offs.

- DSM states (like in linked documents above) that for applications with sustained exposure to UV, protective measures are a must. Stop talking about unprotected Dyneema as lifelines, you can’t do that.

Like many incl. me have stated earlier in the thread: Dyneema lifelines are great, they cross all the boxes, never chafe, last 10 years or more and outperform stainless steel by multiples. All recorded lifeline incidents were with stainless steel, never with Dyneema.
What Dyneema to use? Original Samson Amsteel Blue. You can get it in many colors, I still prefer the original blue but have other colors as well. It is about the protective coating, which is not just the outside of the rope but around each individual fiber. Every ship uses this for mooring lines, only adding chafing protection where the spliced loops go around rusty bollards and they last forever. My 3/8” running backstays are 16 years old and still okay.

[ohthetrees]

Originally Posted by Zygodactyl

Thank you all for your comments. Recommend checking out Blue Wave fittings made by a Danish company specifically for dyneema applications. They are beautifully designed in stainless and aluminum for a variety of diameters and applications.

Do you know where to buy Blue Wave stuff in the USA?

[Snore]

Originally Posted by slug

You get rope burns on your ass with fabric lifelines

Not sure how you use your life lines—- never had that issue

Originally Posted by slug

When fenders and fender boards hang on the fabric they chaff and get locked on

Sails and sheets chafe the fabric

So far no issues with the new jib and to prevent side-loading of stanchions, never run sheets over life lines-snatch block and re-route.

Same with fender boards- use slotted toe rail or stanchion base to avoid side loading stanchions.

Originally Posted by slug

uv burns the fabric to a crisp

100% right- in about 5 years or more. Easy to tell well before failure.