Novice questions about dyneema

[Jweyndling]

Go Colligo’s website. It’s the place to buy Dyneema especially for lifelines. Theirs is pre stretched “Dux” line. They also sell all the clever fittings that you will need to make your lifelines.

[thinwater]

Originally Posted by Dockhead

Well, like-for-like in terms of strength, dyneema cordage is far lighter and far more flexible, with far less stretch. Single braid is not the only way to use this -- double braid with a nonstructural polyester cover is also available.


So I think the advantages are far greater than just being good with low friction rings.


Those advantages are less important on a smaller boat with smaller sails and lower loads; for a larger boat dyneema running rigging is just about mandatory.


My boat was originally built with some dyneema in the running rigging -- staysail sheet, outhaul, running backs. I later replaced the 16mm polyester jib sheets with 14mm racing grade dyneema -- a real transformation, much more control, no more panting, much better handling. Mainsheet from 14mm polyester to 12mm dyneema -- something like half the weight, far more flexible, better handling. I changed my furlers from 12mm polyester to 10mm dyneema. By now, I no longer have any polyester running rigging anywhere.



Dyneema double braid is much harder to splice than single braid, but somewhat easier than polyester double braid since the cover is non-structural. Another advantage of it is that you can strip the parts of the rope which are not handled -- increasing flexibility further.


The OP won't realize all of these advantages because minimum diameters for the sake of handling will limit his ability to downsize the cordage. I would still go with dyneema, if I were he. It's just better.

Yes. Big boat, Dyneema is amazing. Race boat, many applications. Small, detuned trailer boat, not so much.

[Peeew]

Try R&W rope. They buy overstock from truck winch companies and often have great deals.
https://www.rwrope.com/

[CyKlop]

Originally Posted by markxengineerin

Are you sure you want dyneema for running rigging, even for light stuff? It's slippery as hell, not good in rope clutches, cleats, or hands, and doesn't have any stretch to it to absorb shock loads. Not a lot of people using it for running rigging!

For suppliers, check any local chandlery, any mail order chandlery, Sampson ropes, New England Ropes. I expect all of them will offer it by the spool.

Just a note that you can get jacketed dyneema that is not as slippery. Big-name racing boats will use it for things like halyards and such. HOWEVER the stuff is expensive as hell.

I do use Dyneema for some of my running rigging, mainly for the topping lift and and foreguy of my spinnaker pole. I also currently have it for the aft guys. Using it for the guys was a mistake and I either wouldn't do it again or else would go with the jacketed dyneema for several reasons, some of which were outlined above.

[s/v Jedi]

Start with watching YouTube videos about splicing Dyneema. They also show how to deal with clutches, self tailers etc. (add a cover, increase diameter by inserting paracord into the core etc.)

So for halyards Dyneema is the bees knees. You want the strongest, lightest, non stretch rope for this. For a jib halyard, you only need half of it made from Dyneema (like the old wire halyards) so learn to splice it to regular double braid polyester.
Where it meets clutches, winches, cleats, add an outer cover that is spliced into the Dyneema where it ends. If this is too thin for a clutch, pull a thin cord into the Dyneema core and use a larger size cover.

For mainsail halyard you need Dyneema the whole length because of reefing. Here an expensive line like Warpspeed can make sense when your clutch can deal with the smaller diameter or simply replace the cam in the clutch or the whole thing.

For sheets: yes, light weather performance is greatly improved by using Dyneema. If you’re not racing, you could look into blended fibers that are much more affordable but give most of the advantages and still allow to use one size down. I have replaced my sheets with MLX3 which is such a product (and it’s core has the UV coating so you can strip the cover for extra weight savings. Save the cover to use elsewhere.

I recommend using the Samson rope products, mainly because you are assured that they use the real Dyneema fibers. Amsteel Blue is a proven product with certifications that others lack.

[Rothblum]

Originally Posted by trswem

....
... is there a rule of thumb for the size of the Dyneema diameter that you use when replacing running rigging?....

The latest issue of Practical Sailor (April 2024) has a good section on Dyneema rigging, including sizing. For various reasons, the rule that you simply replace your old rigging with Dyneema of the same rated strength may be inadequate.
The main takeaway is that Dyneema is very much oversold so far as chafe and susceptibility to UV. Furthermore, for many applications, you have to use the same diameter as your old rigging. Even further, you may have to use double braid, at a large increase in cost.