Dyneema life lines?

TiggerToo

TiggerToo

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Having made my first ever soft shackles this morning I started wondering: Would there be any reason not to make life-lines out of dyneema, or even jack-stays of the same material?


:confused:
 
I think the main risk with lifelines would be chafe. I know there have been previous discussions on this topic and various people said they use dyneema for that purpose.

Jackstays - can't think why not - mine are 10mm polyester braid on braid so I guess that the same or slightly thinner dyneema would be fine.
 
While Dyneema lifelines are accepted on the racing circuit I would not have them on my boat because when they fail they tend to do so catastrophically. Racing teams with much larger budgets than mine can afford to change them regularly.

Re jacklines, I prefer webbing because they do not roll underfoot.
 
No reason not to if you fancy it, just be aware of chafe as mentioned. The RORC don't allow them as far as I know though just in case you were planning a bit of offshore racing.
 
Woodlouse said:
No reason not to if you fancy it, just be aware of chafe as mentioned. The RORC don't allow them as far as I know though just in case you were planning a bit of offshore racing.
Click to expand...

ISAF allows them. For 2014-2015 the diameters have been increased.

"Offshore Special Regulations Amendment to the 2014-2015 Edition effective from the 1st January 2014

Rule 3.14.6
Amendment:
3.14.6
Lifeline Minimum Diameters, Required Materials, Specifications
a)
Lifelines shall be of :
- stranded stainless steel wire or
- Single-braided High Modulus Polyethylene (HMPE) (Dyneema®/Spectra® or equivalent) rope
(Braid on braid is recommended)"

Personally I wouldn't use them for the reasons that I gave above.


Amendments in the 2014-2015 Edition of the Offshore Special Regulations are in this link just in case you might be affected by them:

http://www.sailing.org/tools/documents/OSR2014AmendmentSheet19122013-[16039].pdf

(Please note that my interest is solely that of Scrutineer for the Rolex Middle Sea Race. I don't race...well, not unless there is another sail in view... ;) )
 
I used 5mm Dyneema to replace old SS guardwires. They are much easier to inspect than plastic covered wire and nicer to hold than SS rope. Replacement is a cheap, DIY job if problems do occur. I did add some tight fitting polythene sleeving where they pass through stanchions but isn't any significant degree of movement so chafe shouldn't be an issue.
 
I have actually written the official 'best practices' document for dyneema life lines - you can fine it here: http://www.ussailing.org/wp-content...yneema Spectra Lifeline Revision Jan 2014.pdf

For a cruiser there are two advantages for dyneema - one is that when you hang clothing to dry they never get any rust marks (as they can even with 'stainless' wire), the second is that you never cut your hand on them. But it is possible (although hard) to cut or melt them accidentally - you need to be espically careful when first installing them to make sure the stanchion holes are very smooth. For a cruiser I would go bigger in size to reduce the cutting/chafe/uv issues - I would perhaps use 8mm in the uppers and 6mm in the lowers. Those sizes would be massively strong and durable.
 
We bought a reel of 8mm, 100m, Liros D Pro and did the whole lot, one reel being cheaper than buying small lots. We have been using them for 4 years and no signs of chafe. They feel 'nice' and are very easy to install. We have used some of the balance on our screecher furler, some for our third reef and both spliced into a larger line for comfort of handling and to fit a winch.

We would not use them for jackstays as having some elasticity seems a good idea. However if you were to use them then you can buy Dyneema hollow tape, Nautilus Braids in NZ. We have used this braid for its chafe resistance as a sleeve over nylon snubbers and to join two sheets, sewn with 0.5mm dyneema braid, also known as fishing line (the braided tube is then 'cow hitched' to the clew, is low profile and does not catch when you tack).

Jonathan
 
estarzinger said:
I have actually written the official 'best practices' document for dyneema life lines - you can fine it here: http://www.ussailing.org/wp-content...yneema Spectra Lifeline Revision Jan 2014.pdf

For a cruiser there are two advantages for dyneema - one is that when you hang clothing to dry they never get any rust marks (as they can even with 'stainless' wire), the second is that you never cut your hand on them. But it is possible (although hard) to cut or melt them accidentally - you need to be espically careful when first installing them to make sure the stanchion holes are very smooth. For a cruiser I would go bigger in size to reduce the cutting/chafe/uv issues - I would perhaps use 8mm in the uppers and 6mm in the lowers. Those sizes would be massively strong and durable.
Click to expand...

Now, that is what I call an authoritative article... are you a VyvCox clone? Thanks!!!!!
 
>For a cruiser there are two advantages for dyneema - one is that when you hang clothing to dry they never get any rust marks (as they can even with 'stainless' wire),

We hung our washing on stainless life lines and never got rust marks, if the lifelines are rusty they need changing. I wouldn't touch Dyneema for halyards, life lines jackstays or anything else on the boat.
 
Incidentally, re my earlier post - I'm able to use braid-on-braid polyester for jack lines because mine do not sit on the side decks, rather they run on top of the coach roof either side of the mast so that I'm less likely to go over the side should I fall or get swept in that direction. I had rope of the right length available when I first tried this out and found that I didn't often tread on them so being round wasn't a problem.
 
What is the UV characteristics of Dyneema as guardwires? Are we talking braid covered dyneema?

Donald
 
Aja said:
What is the UV characteristics of Dyneema as guardwires? Are we talking braid covered dyneema?
Donald
Click to expand...

It's discussed in some detail in the article I linked to above . . . but here is a graph for dyneema single braid (eg uncovered) - the two lines represent the high and low range of a whole bunch of lines that were tested. With single braid you definitely want 'extra' strength to deal with the UV, and the sizing recommendations incorporate that.

View attachment 45253

We unfortunately don't have similar good UV test data for covered dyneema cored line, but it would obviously be some better than the above. However there is some Samson rope test data which suggests that UV penetrates pretty easily thru about 4mm of line/cover, and the covers on life line size rope are in the 1-2mm range, so the cover may do less than one might think.
 
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That's interesting data on the UV penetration of braid covering which would probably chafe pretty quickly in any event. Not sure there is an arguement for changing to Dyneema. Upping the diameter to 8mm will still only give a worst case scenario of 60% loss in strength over 10 years.

Different arguement for jackstays however (other than the lack of elasticity) as I would remove them at the end of the season.

Regards

Donald
 
There is a big debate about covered vs bare . . . . but just FYI most of the covered line used for life lines have dyneema covers which are specifically tightly braided and coated to provide both extra uv and chafe resistance (NER WR2 is an example). I have done some chafe testing and they are in fact extremely chafe resistant, more so that the normal bare dyneema braids.
 
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