Dyneema instead of stainless for stays and shrouds

[Training Wheels]

I thought about rerigging my boat in dyneema, but didn't. It was much more expensive than stainless. It's a cruising boat. I don't want to be dismasted by a pissed off guy with a machete. Dyneema's melting point is low, like 140 degrees I think. So, a line running across it can burn through it quickly. Lastly, I don't want to be on the middle of the Pacific in a gale, and find my rigging has creeped and needs to be tightened.
I love dyneema. Virtually all my running rigging is dyneema. I am just not convinced it's a good idea for standing rigging on a cruising boat.

[seandepagnier]

It's true, the bronze hanks should never have been used on wire prior, otherwise they will have sharp edges. On dyneema, the bronze never wears, so you can keep your hanks from the old sail for the next one.

I also make soft hanks using a piece of dyneema with a spice on one end and a knot in the other. These are nice but are slower to attach.

Originally Posted by Training Wheels

I thought about rerigging my boat in dyneema, but didn't. It was much more expensive than stainless.

It's actually cheaper. It cost me $270 to rig my whole boat with dux, and I have two backstays, and a spare as well.

It's a cruising boat. I don't want to be dismasted by a pissed off guy with a machete.

This never actually happened to anyone. Many people use inflatable dingy, and they are easy to destroy with machete also, but this never happens either.

Dyneema's melting point is low, like 140 degrees I think. So, a line running across it can burn through it quickly.

What line exactly? This scenario is the most unlikely one and never actually happens to anyone.

In fact it's the opposite, the sails and lines chafe up far less than if you have wire rigging.

Lastly, I don't want to be on the middle of the Pacific in a gale, and find my rigging has creeped and needs to be tightened.

This is not a problem, ever. the rigging can be very loose without a problem unlike wire rigging without danger of weakening it.

I did have a gale in the pacific watching the individual strands of wire breaking.

I love dyneema. Virtually all my running rigging is dyneema. I am just not convinced it's a good idea for standing rigging on a cruising boat.

Stick with galvanized then, it has a lot of a advantages over dyneema.

[SV Windrush II]

Fyi, UHMW PE (Dyneema) has a melting point of 267º F but recommended maximum service is about 180º F.

Ref; UHMW (ULTRA-HIGH MOLECULAR WEIGHT POLYETHYLENE) | Sterling Plastics Inc.- Blaine MN plastics distributor

[estarzinger]

^^ there is a concept called 'critical temperature' which is the point at which rope degradation is cause by the temp alone. Samson at least says that is 150F (page 31).

There is some debate about whether (for example) a spin sheet being whipped around/across a stay could generate that temperature locally. The crew on Comanche (top race boat, top pro crew) felt strongly enough that it could (some said they had actually seen such damage) that they rejected dyneema lifelines because they felt it could be cut or melted (this was in record breaking mode where they were not constrained by WS OSR's). I personally have not yet seen anything solid one way or the other on this. But I do know that dyneema life lines were cut rather more easily by accident than most people expected (these were quite public failures), and they were then banned (by OSR's).

There is some data from Samson long term testing with ship mooring lines that extended exposure to less temp than this will degrade the line, but it is comes from ropes actually in commercial use so the data/analysis/conclusion is a bit messy.

[waterman46]

Any data on lifetime of Dyneema for standing rigging? I suppose it hasn't been around long enough. What sort of terminals are used and can the Dyneema be removed from the terminal for inspection like I can with my Norseman fittings on SS?

If some racing rules prohibit it for lifelines, why is it acceptable for standing rigging?

[SVNeko]

Originally Posted by boat_alexandra

Considering how much less reliable stainless is compared to dux, I guess you must mean you use galvanized for the headstay?

I can understand diamond stays staying metal because of temperature changes, the wire and mast expand the same amount. My rigging is always looser when I sail to higher latitudes, then gets tight again in tropical places. Doesn't matter that much since it doesn't weaken from shock loading.

Despite what numerous people had told me prior, I have my headstay in dyneema now for 8 years and use bronze hanks. There is virtually no wear on the stay, and it works fine. There is nothing wrong with hanks on dyneema. I guess all the riggers didn't actually try it, they just like to make assumptions about something they know nothing about.

No, we did not use galvanized wire for the headstay. I don't know about your experience but we found the dux to creep continuously over 2 years and are glad we didn't have to put up with the resulting sag in the headstay or staysail stay, especially with furlers on them. As to the diamonds, they are usually rod on a cat for a reason. We didn't keep it that way for thermal expansion reasons. The mast is aluminum and I imagine it expands/contracts differently than steel. We just don't want the thing going out of column due to the diamonds going slack. Your boat puts quite different stresses on the standing rigging than mine.

[seandepagnier]

Originally Posted by SVNeko

No, we did not use galvanized wire for the headstay. I don't know about your experience but we found the dux to creep continuously over 2 years

I found the splices set, but once set that is it. The dux is already pre-stretched so it doesn't creep. Maybe the spices were just setting? All of my stays set to 4-6 inches longer.

I think you can use bronze wire also, if you want it to last forever. I met 3 boats now stuck in various islands because they lost their rig unexpectedly from stainless failure. In these cases, the wire was only a few years old.

I met someone who finished building their wooden boat in 1969, and had logged more than 120,000 miles and it still had the original galvanized rigging. He claimed he would replace the wire soon because it was almost 50 years.

and are glad we didn't have to put up with the resulting sag in the headstay or staysail stay, especially with furlers on them. As to the diamonds, they are usually rod on a cat for a reason.

What is the reason? Reduced windage?

We didn't keep it that way for thermal expansion reasons. The mast is aluminum and I imagine it expands/contracts differently than steel. We just don't want the thing

The difference with aluminium and dyneema is much greater, so it is probably an issue for diamond stays, but I do not have any.

There is a trimaran next to me which is all dyneema except for wire diamond stays.

[Benz]

Originally Posted by estarzinger

^^ there is a concept called 'critical temperature' which is the point at which rope degradation is cause by the temp alone. Samson at least says that is 150F (page 31).

There is some debate about whether (for example) a spin sheet being whipped around/across a stay could generate that temperature locally. The crew on Comanche (top race boat, top pro crew) felt strongly enough that it could (some said they had actually seen such damage) that they rejected dyneema lifelines because they felt it could be cut or melted (this was in record breaking mode where they were not constrained by WS OSR's). I personally have not yet seen anything solid one way or the other on this. But I do know that dyneema life lines were cut rather more easily by accident than most people expected (these were quite public failures), and they were then banned (by OSR's).

There is some data from Samson long term testing with ship mooring lines that extended exposure to less temp than this will degrade the line, but it is comes from ropes actually in commercial use so the data/analysis/conclusion is a bit messy.

Evans, can you link to similar temp. degradation data regarding Vectran, if there is any? All I can find is that Vectran melts at 625 F, which is a bit higher than Dyneema.
I bring up Vectran because I've found it to be a perfectly suitable option for standing rigging: cheaper than Dux, easy to splice, no creep issues: you just have to keep it out of the sun. My current gang of rigging has a polyester cover (it's Samson's Validator II), but if it ever wears out (showing no signs yet), I might just sleeve a whole new gang of Vectran with Dyneema anti-chafe sleeve.
As for hank chafe, you can slide a whole bunch of round brass thimbles or low-friction rings onto the stay before you splice it, and attach the sail to those either with little pigtails that tie (like I do), or with a spliced loop that you can clip to. Those will run up and down all day with zero chafe.
In places where chafe is a concern, I use Spiroll PVC anti-chafe sleeves taped tightly on with vinyl tape. They work wonders.

[Benz]

Originally Posted by TheThunderbird

PBO, to my memory, has three phases of stretching
First one, forces you to continuous trimming at the beginning
Then, stretching settles down for a few years (?)
later on, stage 3, it ACCELERATES AGAIN, and then you have to two-day.

I think dyneema is, to an extent, a sort of (??)

on a large boat, resilience of SS is worth its weight...and splicing on exotic fibers is, for large size (5/8" or more), quite problematic

Why is splicing on exotic fibers for a large size problematic? It's easier than dealing with Sta-locks on the same size wire. I can splice 5/8" Dux with a plain Samson fid and a box cutter.

[Sailmonkey]

Originally Posted by Benz

Why is splicing on exotic fibers for a large size problematic? It's easier than dealing with Sta-locks on the same size wire. I can splice 5/8" Dux with a plain Samson fid and a box cutter.

+1!

It's a hell of a lot easier to splice large dux than small!

[jt11791]

Originally Posted by waterman46

Any data on lifetime of Dyneema for standing rigging? I suppose it hasn't been around long enough. What sort of terminals are used and can the Dyneema be removed from the terminal for inspection like I can with my Norseman fittings on SS?

If some racing rules prohibit it for lifelines, why is it acceptable for standing rigging?

Lifetime ratings are hard to come by for any type of rigging. Navtec rated their rod rigging in hours of use (50,000?), but of course, and hour of sitting at a mooring is not the same as an hour of beating in 20kts.

Dyneema suffers from UV degradation, so a season on Long Island Sound isn't the same as a season in the Caribbean.

The thing with Dyneema is that the shrouds are sized to get the appropriate amount of elastic stretch, and this makes them way oversized when considering breaking strength. Thus as UV degrades the shrouds it will be obvious way before load limits are an issue.

Terminals are simply thimbles around which the line is spliced. You can inspect the line without removing anything.

Here's where my backstay connects to the masthead.




The shrouds attach to the mast like this:



And connect to the chainplates via traditional turnbuckles:


Another nice bonus is that the Dux shrouds are nicer on the hands when holding on compared to the original SS rod rigging (or wire).

After two seasons, they show little wear, so I expect that I'll get 5-7 years pretty easily. And, now that I have all the hardware in place, when the time comes I can replace all the lines for hundreds of dollars rather than thousands.

[jt11791]

I should add that I left my forestay as SS rod, because I wasn't sure about putting a roller furler over Dux. The Dux is fatter than the rod and I wasn't sure my foil was going to fit over it easily.

[Jim Cate]

If some racing rules prohibit it for lifelines, why is it acceptable for standing rigging?

This was such a provocative question that I repost it here! We use and trust Dyneema life lines, but this question does merit an answer from some knowledgeable soul.

Jim

[estarzinger]

Originally Posted by Benz

Evans, can you link to similar temp. degradation data regarding Vectran, if there is any?

300F critical temperature for vectran - not likely to be a problem except for a real severe mistake.

yea, you and I are fans of vectran; and I agree with your hank and chafe suggestions. I had a whole bunch of very little dyneema loops spliced around my dyneema innerstay, and I hanked to them, and everything ran up and down real smooth. And I used the same spiral wrap on my dyneema backstay where the mainsail overlapped it.

[SV Windrush II]

Originally Posted by jt11791

.

Terminals are simply thimbles around which the line is spliced. You can inspect the line without removing anything.

Where did you get your composite thimbles?