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Synthetic Rigging for a Trailer Sailer

Oct 22, 2014
9,926
CAL 35 Cruiser Portland OR, moored EVERETT WA
Hi Judy
While certainly I am not an expert on dyneema rigging, I did study the issues when I was looking at replacing the rigging on my boat a few years ago. The following are some of the major elements.
  • In comparing Dyneema vs SS insurance requirements for ocean going vessels, Dynemma rigging required inspection annually, professional survey at 3 years and replacement at 6 years. The engineering reports were that being stronger and lighter was a big advantage. Going up in size (as you suggest) was a way to build in safety margin with little additional weight and marginal added cost. One of the underlying concerns were the hidden breakdown of inner fibers from the stress of sailing use and UV exposure.
  • By comparison the SS stays were lower cost, greater weight. They have a proven record with more obvious failure points so self inspection annually and professional survey after 8 years, ocean passage, or rust/wire strand break were recommended.
These points are what supported my statement of "that SS wire is better for multiday and multiweek cruisers" in comparison to that of dyneema. Certainly if you are able to afford the initial and ongoing cost of dyneema the fact that it is relatively easy to install and replace in the field once you learn to tie a knot or splice it. Wire stays really require hydraulic mechanical swage fitting to provide a secure fitting by comparison.
 
Apr 13, 2018
26
O'Day 19 Rexford, NY
That's what I get for posting on my lunch break: I meant to say pre-stretched (and heat treated). Haven't seen a mention of those exact terms on NERopes' page on the HTS-78, however... Just "ultra-low creep". It's all relative...

I'll reach out to Kevin and see what he says. Thanks!
 
Oct 22, 2014
9,926
CAL 35 Cruiser Portland OR, moored EVERETT WA
@theluckyone17
This the stuff of which you speak.
Dyneema Dux, which is, I believe, prestretched and heat treated SK75
Not sure you really need it for a 19ft boat.
The product you seek goes by the names:
Dyneema (c) is a registered trade name of the Dutch company DSM Dyneema, B.V. They have a factory in Greenville, NC, U.S.A.
Spectra (c) is a registered trade name of the U.S. firm Honeywell International Inc.

Both are fibers independently developed by their respective manufacturers and while their production details likely differ, both are made of Ultra High Molecular Weight Polyethylene, or UHMWPE fibers. The following shared characteristics:
  • Weight for weight, they are up to 15 times stronger than steel and up to 40% stronger than Kevlar (c) (DuPont).
  • Being slender for their strength, they offer less aerodynamic drag than other types of line.
  • They are more abrasion resistant than high carbon steel.
  • They are resistant to UV light.
  • They do not absorb water (and they float).
  • They exhibit very low stretch compared to nylon or Dacron lines (like comparing steel wire to rubber bands).
 
Jun 25, 2004
507
Corsair F24 Mk1 003 San Francisco Bay, CA
Construction stretch is a big consideration with standing rigging that has to be tuned, even for a 19 foot boat. That is a strong argument in favor of using heatset SK75 over non heat set dyneema. Otherwise every time you reassemble the rig, it’s going to be too short and tight to pin the forestay. every stay and shroud gets shorter whilst the rigging is stored during trailering.

In my experience using dyneema on three boats since 2013, Heat set sk75 dyneema behaves and feels very different from plain sk75 dyneema and sk78 dyneema. It feels much harder and stiffer and more compact. It tunes almost exactly like wire rigging.

In short, here’s what I’ve learned from my limited experience with dyneema vs wire:
Use heat set sk75 for standing rigging that you tune. Size it for stretch, not strength.
Use sk78 or 90 for adjustable rigging like adjustable backstays and runners.
Use wire for mast raising systems.
 
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Jun 25, 2004
507
Corsair F24 Mk1 003 San Francisco Bay, CA
That’s not a thimble it’s a tear drop shaped eye. I still don’t understand how a big eye has anything to do with splicing synthetic rigging around a thimble.

Sizes of holes and pins have to match to eliminate point loading. I can’t visualize how the big teardrop eye mates with a cast, one piece thimble of appropriate strength and design.

See https://static1.squarespace.com/static/556621c8e4b02628a8d3bde8/t/55eed560e4b0c46828eff148/1441715552357/terminatorchart.pdf
In that diagram, dimension A has to match the hole in the tall.

 
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Apr 13, 2018
26
O'Day 19 Rexford, NY
Ah... that might just explain why those Colligo thimbles are a bit more expensive than simple SS thimbles. That hole in the middle allows for a shackle pin (sleeved or unsleeved), eliminating a point load. NICE!
 
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Sep 8, 2014
2,549
Catalina 22 Swing Keel San Diego
Yes and no... Never used NE HTS (and not sure if thats what the OP meant or it was a typo), but STS HSR is heat set and essentially the exact same thing as Dux. I have used it extensively.
 
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Sep 8, 2014
2,549
Catalina 22 Swing Keel San Diego
I started to watch this video however at the beginning he suggested that if we had not seen his earlier video, we watch that first.... so I did. It is an excellent video on splicing. He made it look SOOOOO easy and his splices were very professional. It is a link worth watching IMHO.
I made the Deadeyes for this boat, and helped James fix various other problems. I also made a set of cascades with 4:1 tackle, one on each of the twin backstays. He has not done a video on them yet because he is still trying to work out some issues. There is no problem at all with my cascades, the issue is that he ordered a new Main that has a massive roach compared to the original sail plan. When he Jibes he keeps hitting the roach on the stay, the only way to get the main to pass under the leeward shroud is to pull it down to the third reef. The only solution I can give him at this point is to relocate his chainplates (I have the original drawings for his boat, the full plans. This is safe to do) but he's not in a part of the world where can effectively do the boat work just yet.
 
Sep 8, 2014
2,549
Catalina 22 Swing Keel San Diego
That’s not a thimble it’s a tear drop shaped eye. I still don’t understand how a big eye has anything to do with splicing synthetic rigging around a thimble.

Sizes of holes and pins have to match to eliminate point loading. I can’t visualize how the big teardrop eye mates with a cast, one piece thimble of appropriate strength and design.

See https://static1.squarespace.com/static/556621c8e4b02628a8d3bde8/t/55eed560e4b0c46828eff148/1441715552357/terminatorchart.pdf
In that diagram, dimension A has to match the hole in the tall.
This are called "T-Bails" (I believe), and you do not use a thimble with them. You are supposed to luggage tag the spliced eye of the dyneema shroud through the welded eye. This is somewhat problematic as it interferes with the correct bend radius of the Dyneema, but I haven seen anyone publish data on break-testing with that type of termination. For boats with Stem-Ball terminations and T-fittings, the switch is difficult because there isn't much hardware out there yet or it has to be custom made. Buying all new mast termination hardware kind of eats into your budget and eliminates much of the savings. The easiest and least expensive way is traditional pairs of tangs to slot the thimbles into with clevis pins just like the wire was.
 
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Sep 8, 2014
2,549
Catalina 22 Swing Keel San Diego
You typically use DUX, which is pre-stretched dyneema. Not cheap. While synthetic has advantages (and disadvantages!) at the end of the day cost savings will probably not be one of them.
Cost savings is thrown out the window when you buy DUX because its marked up over 400%. There are many other lines out there that are the same chemical formulation as DUX, but every rope manufacturer weaves differently and the heat annealing process varies. I use Marlow D-12 Max in sk78 and sk99, it priced far better than Dux and matches or beats it in performance on every measurable factor. NE Ropes STS HSR is also excellent. I'm rigging a 42 Ft Bob Perry designed double ender with 9mm D12 max sk78, there are 12 total shrouds/stays in this rig not counting the forestay (remains wire for the Harken furler). I've finished the 4 stays that pass through the spreader tips so we could re-step the mast, the remaining shrouds will be installed at a later date when the owner recovers from the financial typhoon that with him (the yard bill). Anyway, the total cost for this job is about the same as what he was quoted for a wire rig, $9K. This includes all new Hayn 5/8" Turnbuckles and we are using Colligo Male Chainplate distributors rather than my flavor of Deadeyes. The Colligo units plug in nicely to the new turnbuckles to create a short deadeye system. Its recommended that heavy displacement boats stay with turnbuckles for primary tension. BTW, all the shrouds I make are fully covered with Dyneema chafe sleeve, all the way around the eye and sewn almost seamlessly.
 
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