Dyneema Lifelines

[Oldlaxer1]

This place does all sorts of rigging with their version of Dyneema including standing rigging.   They have a section on lifelines too. 
https://www.colligomarine.com/

Here is a link to a bunch of youtube videos from their site.  pretty helpful.  Good luck.
https://www.youtube.com/results?search_query=colligo+marine+lifeline

[PaulJacobs]

Wow!  Many things to consider, and many useful ideas.  To keep things both very safe and aesthetically attractive, and to MINIMIZE extra hardware, while still maintaining functioning gates (even though in 9 years we have entered and exited Pleiades literally thousands of times through her open transom, and exactly twice "over the starboard side" when we were visiting Nancy's brother at the Eastern Yacht Club, in Marblehead, MA, where their YC launch picked us up and later dropped us off).  My "final" plan, based on inputs from many of the above, is as follows:

1. Generate a 6" circumference "eye splice" using a whipped Brummel splice on one end of the Dyneema line.
2. Create a "cow hitch" (sometimes also known as a "luggage tag") around the bow pulpit 1" diameter SS tube, but through the SS welded "eye" to avoid slipping down the pulpit... exactly as shown in the Collego video.  This has the advantages of (a) using a larger diameter very smooth surface, hence lower local stress concentration or chafe potential for the Dyneema, and (b) also uses ZERO extra hardware at the bow.
3. Thread the 1/4" "silver" Dyneema line through ALL the stanchions - including the gate - as well as our Navy blue upper lifeline covered foam "backrests", and then generate another 6" circumference eye, whipped Brummel splice on the aft end of the lifeline, and attach it again via a cow hitch to a 3/8" Witchard pelican hook (only $9 each). 
4. Finally, using 1/8" diameter Dyneema, create a roughly 4-6 inch long "4-part lacing" to tension the Pelican hook.
5. Let all the lifelines "relax" for a few weeks to complete any "creep".  Then re-tension until they are nice and snug.
6. NOW - and I note that none of the web sites show this idea - using a needle, and heavy duty whipping twine, complete a multi-pass "through whip" (i.e. pass the needle through the Dyneema, around multiple times with the whipping line, then back through again, to insure that the whip does NOT move) immediately aft of the gate stanchion.  This will keep the entire forward portion of the lifeline taut EVEN WHEN you release the pelican hook to enable side boarding!

Finally, once every few years you can intentionally (a) undo the pelican hook and the whipping, (b) let all the lifelines go slack, (c) inspect at each stanchion location for any chafe, (d) and if all is well, re-connect the pelican hook, re-tension the lacing if necessary, and replace the whipping.

[Admiral_Swellson]

From this page here: https://www.colligomarine.com/techblog/2017/4/11/synthetic-lifelines

They say: "Colligo Marine® Dux Lifelines are the strongest and toughest synthetic lifelines available. If the lashings are changed every 2-3 years your lifelines will last least 5-8 years in the tropics."

That's less than I would have expected, is anyone else concerned or is cost over stainless steel so advantageous that it doesn't matter?

[PaulJacobs]

Robert & others,
I have been in the middle of all of this discussion - as I will be changing Pleiades lifelines this spring.  Interestingly, both 1/4" diameter Dyneema and 1/4" diameter SS wire are pretty close in price, at "about" $1.70 / foot - depending on where you buy it, who is having a sale on a given day, and the day of the week.

However, the REALLY BIG difference in cost is that unless you happen to have a swage machine (I certainly do NOT, and I suspect the vast majority of other C34 owners also do NOT), a major expense associated with using SS wire is the need to use a professional rigger!  You are then paying for all the time he or she needs to carefully measure, and do about a dozen swage compressions, at an average of probably three per lifeline, and more with "gates" - PLUS the cost of all the considerable number of turnbuckles, SS pelican hooks, SS "eye" terminators, etc.

With Dyneema one simply performs multiple Brummel splices.    The first one probably takes 20 minutes.  The second one perhaps 10 minutes.  By the time you are doing your third Brummel splice it takes about 5 minutes.   I know this because I did about a dozen for a friend some years ago, and the learning curve was extremely steep.  Finally, using the method I noted in an earlier post, the number of terminations is much less with Dyneema, and the only "hardware" involved to do four gates (upper & lower lifelines, both S&P) are four pelican hooks at $9 each!  Including 125 feet of 1/4" Dyneema, and 30 feet of 1/8" Dyneema, for the "lacing", a completely new set of lifelines will cost me just a bit over $200.  If I went with SS wire, the SS turnbuckles (which are about $50 each, and you need 8 of them if you include gates on all four lifelines), terminators, pelican hooks, and SS wire rope would be around $600, plus another roughly $400 in labor for the professional rigger, or about $1000 total.

Furthermore, Dyneema will NEVER RUST, is incredibly strong, and while chafe can be an issue, as noted it is a simple matter to undo the lacing, and whipping, every two years, and check.  If chafe is spotted in say 4-6 years, one can always shorten the lifelines about 2" by redoing the Brummel splices and whipping, which will move the incipient chafe away from the stanchions, and then slightly increase the lacing.  At that rate they should last at least 20 years.

Paul

[Admiral_Swellson]

In case you haven't seen this, Catalina direct has it in kit form, including tools, starting at $700. depending on how many gates you want/need.

https://www.catalinadirect.com/shop-by-boat/catalina-38/lifelines-stanchions/lifeline-deluxe-kit-sgl-gate-no-vinyl-c-34-c-350-c-36-c-38/

[ErikN]

I'm considering this as well, but I have an additional concern: is dyneema susceptible to mold/algal growth? If so, is it easy to clean? This is probably more of a problem here in the PNW than in some other areas.