Dyneema versus wire.

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Gwylan

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Guard wires are old and a stanchion got broken recently.

So I'm wondering about maybe using dyneema. I can work with dyneema and fit it myself.

Is this a good idea or should I stick to getting new wire made up for me?
 
I have had a brief look at the first previous thread above ... but there is a LOT of misinformation about.

I have Dyneema guard lines .... Amsteel Blue, single braid:
1 no perceptable UV degradation after 3 or 4 years.
2 no chafe in the stanchions or where I tie the front awning on ..... living on board throughout. Awning is big so gets buffeted by the wind hence lots of opportunity for chafe .... but none.
3 creep is a problem at first, and you will have to tighten the lines for the first few months. I use a lashing at one end to make it easy.
4 knotting can be a problem if the wrong knots are used. You certainly do not want to knot the standing part. It is slippery so using the wrong knot can come undone. Spicing is very easy and the Brummel spice is particularly good and rewarding to make.

Don't forget that Dyneema has been regularly used in potentially high chafe and high UV areas for years: running rigging, fishing boat gear, trampolenes ..... and it is still used and trusted.
 
Here are some relevant sites:
http://www.colligomarine.com/docs/respecttherope/RTRDyn1.pdf
http://www.samsonrope.com/Documents...atically Loaded Synthetic Ropes_March2011.pdf

Colligomarine use Dynex Dux which is heat treated Dyneema and hence is less flexible that the Amsteel Blue.

Using the correct knots, chafe, and UV degradation are not usually a problem because the Dyneema rope should be several times stronger than the requires load .... for instance using 8mm Amsteel Blue would give 4 x the strength of the 3/16" 7x19 stainless wire that is normally used. Hence any damage should be seen before it becomes a problem.
 
My comments above on Sampson Ropes Amsteel which is single braid and thus has no protective sheath. Obviously a sheath will protect the core Dyneema .... but the Dyneema would have to be that much thinner to pass through the stanchions. An outer sheath would make the Brummel spice impossible without going back to core-only at the end. Other through-sheath spices would have to be used or the end protected against UV and chafe to make up for the thinner Dyneema braid used.
 
We've had Liros 'Magic Pro' unsheathed Dyneema on our lifelines for over 5 years (and we are in the land where UV was invented:)), no degradation we can see and it feels as strong as ever. No abrasion where it passes through the stanchions. We have been also using the same braid as our furler line on our screacher, no abrasion no damage from UV.

We used a scaffold knot. We also used turnbuckles that mean as the knots tighten you can tighten the slack.

UV damage on Dyneema has been talked about since its introduction in the 80,s (?). Strangely I have never seen any quantitative data for or against the issue but it must have been grossly overstated as the amount of unsheathed Dyneema now available, to be used outdoor in very high load applications, is immense. Equally abrasion resistance, or lack of, was another fear put about which also seems to be another red herring as, unsheathed, Dyneema is being used in many high abrasion applications. Ethchells use unsheathed Dyneema for virtually all controls, sheets, halyards now (maybe a cover where they are cleated off, and they last forever despite commonly sitting out in the sun all day (well sun in Oz, HK and Calif etc:)

If anyone has quantitative data to support its poor UV or poor abrasion resistance (as opposed to anecdotal information) I'd love to see it.

Jonathan
 
J Neeves said:
We've had Liros 'Magic Pro' unsheathed Dyneema on our lifelines for over 5 years (and we are in the land where UV was invented:)), no degradation we can see and it feels as strong as ever. No abrasion where it passes through t he stanchions. We have been also using the same braid as our furler line on our screacher, no abrasion no damage from UV.

We used a scaffold knot. We also used turnbuckles that mean as the knots tighten you can tighten the slack.

UV damage on Dyneema has been talked about since its introduction in the 80,s (?). Strangely I have never seen any quantitative data for or against the issue but it must have been grossly overstated as the amount of unsheathed Dyneema now available, to be used outdoor in very high load applications, is immense. Equally abrasion resistance, or lack of, was another fear put about which also seems to be another red herring as, unsheathed, Dyneema is being used in many high abrasion applications. Ethchells use unsheathed Dyneema for virtually all controls, sheets, halyards now (maybe a cover where they are cleated off, and they last forever despite commonly sitting out in the sun all day (well sun in Oz, HK and Calif etc:)

If anyone has quantitative data to support its poor UV or poor abrasion resistance (as opposed to anecdotal information) I'd love to see it.

Jonathan
Click to expand...
Evans starzinger had some data from a manufacturer of up to 50% weakening over 5 years due to uv over on cruisers forum from memory, you could try a search. Even so, it will still break something else before it goes.
Based on his recent testing your knot will probably slip before that as well.

Edit:
uvexposure.jpg


From here for single braid.
http://www.bethandevans.com/load.htm
 
Last edited:
Tending to err on the side of Dyneema - we have used it in a number of places rather than wire. Mostly because we could fabricate to our own length and spec. Rather than chasing around looking for a rigger who wants to do a couple of fiddly little jobs.

Next have to look for best deal and expect to possibly have to dispose of it in 4 or 5 years. Academic really, it is unlikely that I'll still be sailing then.
 
....bump to an old thread.

I'll shortly be replacing my guardwires and am leaning towards using dyneema. This thread, and particularly the link in estarzinger's post above has been hugely helpful, but I'd be interested to receive any advice from readers who've gone the dyneema route.

And secondly, has anyone any recommendations for a UK source of suitable dyneema (probably 6mm, double braid, unless anyone has a better suggestion).

Thanks.
 
I replaced my approx 4mm plastic covered wire lines with 5mm d12 type Dyneema 2 years ago. Performance has been very good, no significant chafe.

I have locked Brummell splices at each end. At the pulpit, the line is cow-hitched around the pulpit tube, going through the welded on loop. The eye-splice will pull through the stanchions, and at the push-pit a s/s ring is cow-hitched into the splice and the lanyard secures through that.

I much prefer the Dyneema to the wire. Making up the lines was easy, and much lower cost than getting wire lines swaged up.

Possible source for line:-
http://www.ebay.co.uk/itm/DYNEEMA-R...hash=item4cec03b255:m:m_Cp-OKxiTDaJWlASon-6Vw
 
One interesting point that I discovered when interviewing Craig Horsefeld who fell off his Mini while singlehanding. His biggest problem was getting back on board. The wire lifelines were in his way and it took some 10 minutes for him to squeeze over the lines. We discussed that if he had used Dyneema lifelines, he could simply have cut them away. (He already had his knife in hand. He'd used it to puncture his PFD that was in his way.) And once on board with a bit of new line he could have rebuilt the lifelines again.
 
Apparently Dyneema will abrade, I think it melts, if a sheet or guy impinge on the lifelines for prolonged periods. I think this happened on Comanche on a long ocean race.

Its not a feature that concerns us. We have been using dyneema, no outer sheath, for 4 or 5 years now. One turnbuckle at one end, scaffold knots for the dyneema. Much prefer it to stainless wire.

This is on a 38' cruising cat.

Jonathan
 
Foolish Muse said:
We discussed that if he had used Dyneema lifelines, he could simply have cut them away.
Click to expand...

How easily does dyneema cut? I ended up with some cast-off dinghy halyards in an unknown high-tech fibre a while ago, and despite being only about 4mm diameter they were a bugger to cut with a knife.

Pete
 
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