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Old 14-08-2016, 05:22   #1
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Minimizing stretch along Main's halyard

Dear Guys,

I use a 12mm Gottifredi&Maffioli SK78 dyneema globstar.

However, in a few hours I come up with a slack luff, by say 2" .
Main is full batten, and cars work badly, mainly so for the lowest 3 ones (the most spaced out).

The full line is 70'+ long, and it is set as tight as I can, with Spinlock block and four turns around a 27X winch +self-tail fully engaged: no slippage!

Electric winch can't do any better...

Which solution do you suggest, please, in order to reduce total elongation under work?

- 14mm Dyneema?
- Spectra line, with a (final) cover, of 12 or 14 mm !?
- other?

Boat is sturdy, and first reef comes beyond 25kn only.
Quite surprisingly, Genoa line stretches much less (and it is easier to tighten up)

Maybe... this is the first time I will appreciate some racers' comments :-) :-)

Best regards, and thank You!! :-)

Gian - sv Vihuna
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Old 14-08-2016, 13:39   #2
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Re: Minimizing stretch along Main's halyard

Okay, so after that jab at racers, we should help you on this why?
I’d give you 100:1 odds that I can find 20+ things which have trickled down from racing on your boat. And without even trying hard

This problems sounds more like halyard creep than stretch, if it is the halyard. Particularly if it's a Spectra one. So I'm wondering what your sail's made of? As unless it's Kevlar, or something similarly low stretch, then the sail may be where the problem is actually occurring. Have you tried a cunningham? AKA the cheap "fix".
Were I there, I could tell which of the two were giving you trouble with a 15 min on the water session, but...

For determining halyard (or sail stretch), one thing I do on all boats, but especially when I’m racing & am in charge of the halyards. Is to put a grid pattern onto the deck, & a witness mark on the halyard. It lets me reliably repeat the halyard settings for each sail. Be it #1, #2… to #5 Jib with the same halyard. And due to the grid pattern, I know that if I keep having to take up on the halyard in order to keep proper luff tension, that if the sail isn’t stretching, then the halyard is.

You can easily try this on your boat, via putting down what amounts to a ruler (grid) onto the deck or spar with a magic marker. Or use pre-made stick on versions. And also add a witness mark to the halyard.
If you’re putting one onto the deck, it should go about 1m away from the spar. In between the spar & your halyard winch. Assuming that the distance is more than a couple of meters. As the portion of the halyard which is closer to the spar is were there will be more stretch/movement in the line, as opposed to if you were to put the grid right next to the winch.

Then tack several times in a stiff breeze, with the sail up & a fully tensioned. So that after some load’s been put onto the halyard by the sail, if the witness mark creeps towards the mast under load by any significant distance, then the halyard’s stretching.
And if you keep having to wind more halyard tension on in between tacks, & the sail isn’t stretching. Then again, the halyard’s the issue.

Also, it obviously helps if you keep a log of where the witness mark falls on your reference grid, for each wind strength, & each sail. As well as when you’re determining if the stretch is in a sail or in a halyard.


If you're sure it's the halyard, then there are a few cordage options. They aren’t listed in any special order. Though I’m a fan of Vectran from racing big boats/Maxi’s. Or Spectra blended with Vectran or Kevlar. But most of the choices are fairly close to one another.
Note: I haven't sailed using the Heat Set Dyneema for halyards, or using the SK90 Dyneema on any boats of real size (over 40’). So I’m not sure where they fit in the lineup. Though obviously both are well thought of, & supposedly don’t creep under load.

Also, if you look at any of the cordage manufacturer's websites, they have the numbers for each type of line which show how much each stretches at various percentages of it's breaking strength. So using these, you can figure out what stretches the least. With the caveat that most purely Spectra/Dyneema lines except for the Heat Set ones, have creep when used as halyards. Though SK90 has less than the lower grades do.

- Vectran & Spectra Blend Halyard ~ like Samson’s VALIDATOR SKB
- Kevlar or Technora & Spectra Blend Halyard ~ like T900 <-- An old favorite of Brion Toss
- Vectran (unblended)
- 2:1 Halyard SK75 or better
- Kevlar or Technora (unblended)
- PBO ~ Virtually zero stretch. But it’s more allergic to light than any Vampire, even light bulb light breaks it down
- Heat Set Dyneema or SK90 Dyneema ~ Again, I’ve no relevant firsthand experience with this, so how to rank it’s unknown. Both in terms of creep, & lifespan.

Also, on a boat of the size you’re fitting out, it REALLY pays to add extra chafe protection to lines anywhere they regularly pass over a sheave, exit the mast, or connect to hardware. Be that an extra cover, or coatings like RP25 or Maxi-Jacket II. And RP25 helps to bond jackets to cores, as well as adding abrasion resistance, & aiding in holding power in clutches, etc.
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Old 14-08-2016, 14:21   #3
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Re: Minimizing stretch along Main's halyard

PS: You can always ask the same question over on Sailing Anarchy Forums, as there are plenty of guys there who are up to speed on the latest cordage. Not to mention halyard & sail stretch issues.
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Old 14-08-2016, 16:12   #4
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Re: Minimizing stretch along Main's halyard

A Uncivilized, you win the best answer title.

A lot of good,solid information.

The idea of the sail's luff lengthening is not a remote one.. an old dacron tri-radial. In That case, working it tighter is the solution.

I have a block on mast,which i will disengage to check for any movements.

So many Great tips. Many thanks from a slow cruiser :-)

PS I knew that creeping happens after some time,and mainly on Spectra
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Old 14-08-2016, 19:02   #5
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Re: Minimizing stretch along Main's halyard

Yes, a dacron sail on a boat that size will stretch like crazy. The loads are just too high for the material. Even high tech sails on something that size stretch an inch or three quite easily. And it's questionable if you're putting as much load onto the halyard with that size winch as the sail does. Especially if you're not reefing until it's blowing 25kts.

Are you using a Cunningham? They won't fully correct the problem, but one will surely help. Plus it's great as an extra trimming control.
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Old 14-08-2016, 22:28   #6
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Re: Minimizing stretch along Main's halyard

Just to clarify. What you're experiencing is not creep it is constructional stretch. This has to work itself out every time the line is un tensioned and compresses. Dyneema is notorious for this because it has so little actual stretch it is noticeable. But the line needs to be tensioned as hard as possible let for 30 minutes then retensioned (possibly even easing) it back to sailing halyard tension.

It is very possible that a Dacron sail could have far more stretch than the halyard does, but first you need to tension it hard.
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Old 14-08-2016, 22:49   #7
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Re: Minimizing stretch along Main's halyard

Thank you!

I will use Cunningham and re-tension the halyard after a while,use a marker and TP ...:-)

One day a new main will help too
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Old 15-08-2016, 02:44   #8
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Re: Minimizing stretch along Main's halyard

If re-tensioning is needed, i would not define Dyneema SK78 (BEST GRADE availabile in 2014) as best material for halyards...

May i ask you your view on Genoa sheets, then!? I just broke a 14mm nylon line, and will consider something exotic to this purpose

Either specific, or by using the main's halyard as a substitute.

Re-tensioning sheets is more in my acts of sailing :-)
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Old 15-08-2016, 05:31   #9
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Re: Minimizing stretch along Main's halyard

This page might be of interest..

Stretch Test! - Chicago Yacht Rigging Inc.Chicago Yacht Rigging Inc.
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Old 15-08-2016, 21:16   #10
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Re: Minimizing stretch along Main's halyard

Quote:
Originally Posted by TheThunderbird View Post
If re-tensioning is needed, i would not define Dyneema SK78 (BEST GRADE availabile in 2014) as best material for halyards...

I'm not clear what the above statement means, could you please clarify?

May i ask you your view on Genoa sheets, then!? I just broke a 14mm nylon line, and will consider something exotic to this purpose

Either specific, or by using the main's halyard as a substitute.

Re-tensioning sheets is more in my acts of sailing :-)
For the genoa sheets, more information is needed. To start; sail area of largest headsail, wind range of sail including maximum, type of sheet attachment desired, & boat weight.
The question as to why, runs through my mind, if you're after exotic jib sheets for your boat. And also, would they make sense at all? There's little point in using Vectran sheets on a Dacron jib. It's like using Ferrari level tires on a 30yr old estate car.

Also, for selecting running rigging, you might peruse these pages. They're not perfect guides, but serve as decent starts:
Sailboat Line & Running Rigging Selection Guide | APS
Sailboat Line - Extensive Selection | APS

And as stated before, do a bit of reading at some of the various cordage manufacturers websites. Below are some of the major players in the recreational market. Especially mid-high end, & high performance.
www.samsonrope.com
www.neropes.com
www.yalecordage.com
Welcome to Marlow Ropes Ltd
::┬*Teufelberger:┬*FSE Robline«
Alpha Ropes
Colligo Marine«
GOTTIFREDI MAFFIOLI

Plus there are a few dozen others.
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Old 15-08-2016, 21:33   #11
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Re: Minimizing stretch along Main's halyard

Sure the main was built to handle 25+ knots without reefing? The fact that this happens after a couple hours is a bit odd.
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Old 15-08-2016, 21:59   #12
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Re: Minimizing stretch along Main's halyard

Quote:
Originally Posted by Don C L View Post
Sure the main was built to handle 25+ knots without reefing? The fact that this happens after a couple hours is a bit odd.
Yes, I thought the same thing. Trebly so, now in light of the fact that it's Dacron. Enough so that I'm tempted to call BS.

Care to share pics of said sail when being flown in 20kts+ ?

The other question is, is the halyard winch for that sail really a Barient 27? As that's a tiny winch as compared to the power needed to tension such a halyard. Or to lift a Dacron sail of that size.
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Old 15-08-2016, 22:08   #13
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Re: Minimizing stretch along Main's halyard

How are the sheaves up top? I had a split sheave for a while without realizing it a while back.
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Old 16-08-2016, 00:28   #14
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Re: Minimizing stretch along Main's halyard

Sheaves are old Lewmars for 14mm lines.
Should I consider lighter ones, with bearings?

Main is some 10yrs old, BS.... not aerodynamic but robust. I reef once at 25kn apparent wind. Thus I keep heeving at 15-20░maximum

Genoa intermediate is 60+sqm on Harken cars 1" wide. Displacement is 27t. Soft shackles.
I agree that exotic sheets sound stupid, but I broke 14mm nylon sheets, and I have 08-14 Spinlocks

Funny enough,out of the 6 Winches available at mast-foot, all are 27, but a 24 and a 28electric... and I agree they are not large enough...

Thanks for references... I went for GOTTIFREDI, and their Dyneema SK78 looked like best choice 2years ago for heavy cruising...I find it stiff, abrasive on hands, prone to twist and with memory when released out of the winch.

Their site states that Spectra is confused with Dyneema but has lesser quality... that which confuses me...

Also, given the continuous upgrade and new releases of exotic lines... I feel doubtful that 10+years old Vectran is still on the edge...!? :-)
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Old 16-08-2016, 08:43   #15
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Re: Minimizing stretch along Main's halyard

Most anything you use in place of Nylon for your sheets will work better, given how Nylon stretches. As to what you choose, it sounds like you have some biases already. So doing some self-education will help in choosing. After which you might run your top 3 to 5 choices past us.

The use of clutches is somewhat limiting line wise, in terms of both line type & line size. And too, they only hold so much load, which, with a jib that size, they’re starting to get worked hard at times. Good ones will be up to the task, but their size has to be matched really closely with the line in order for them to hold well. And they’ll eat lines faster than other securing methods. In addition to being a good bit more sensitive to how kink free a line is when it’s time to tack/release your lines.

Vectran is more like 25 years old, as we used a little of it in the early ‘90s, & it was common a few years later. And Vectran can be safely used at a higher percentage of it’s breaking strength than some others. That said, the age of a material doesn’t mean a lot, given that Kevlar is ancient, & PBO is very old, yet both have awesome strength & stretch resistance. Even SK75 or 78 isn’t bad, they just have a bit of creep when used as halyards, but are plenty strong. And their poor press is based on the fact that they’re not what top tier racers use now. That’s pretty much it. Well, other than the obvious Meaning, if someone can sell you a new line every year or two…

I use SK 75 on anything but Grand Prix boats, but for some halyards. Otherwise look at the lines mentioned before, & some with Dyneema blend cores. Also, when heavily loaded, many Spectra/Dyneema lines grow stiff, it’s a property of the material. Though for this to happen, it needs to be pushed harder than you’re doing, especially with your halyard.

The handling issues you’re running into with your halyard is likely a tight cover. And probably some internal twisting & kinking of the line’s core. Exorcise the latter ASAP, & regularly. They’ll kill the line.
That said, a tight cover is what you want on such lines, as it adds to their lifespan. Since the cover is there to protect the core & provide a gripping surface. With a softer & looser cover, the core will palpably slide around inside of it, & the line will be harder to effectively use due to this. Including having the core wanting to snake out of the cover, unless mechanically fastened to it. This phenomenon is something which Dockhead noticed & hated in his “Cruising Dyneema” lines. But he loves his “Racing Dyneema" lines, with their tight covers.

One thing you’ll run into when looking for lines for a boat that size, is finding a supplier who keeps much 12mm & larger exotic cordage in stock. And by exotic, I mean anything other than Dacron. As most of their customers buy 11mm or smaller in the super low stretch lines.
So you may want to decide on one line type & size to use for both a new halyard as well as a new sheets, & then purchase a spool of it. Unless you can find someone who’ll sell you cut lengths of what you want in the larger diameters.

Also, until you change to a more high performance cloth in your main, there’s really no need for a different halyard in my opinion. It’s more a want than a need, given Dacron’s stretch.

A trick commonly used to save $ on high cost lines, is to use a “Tail Splice”, & only buy as much high cost line as will really see load. With the rest of the halyard or runner tail being made of plain Dacron.
In a halyard it means that on say a jib halyard, the part which would be Vectran with a Dacron cover would be long enough to go from the head of the shortest jib, through the masthead sheave, down to the deck, & extending past the winch/stopper by a few meters when the sail is at full hoist. A Dacron piece is then spliced in order to make the halyard long enough to be able to be clipped to the deck at the bow, run over the masthead sheave, down to the deck, & past the winch/stopper by a few meters.
All in all, a neat trick, given that Vectran is 2-4x the cost of Dacron.

Or, the other way to do things when you buy a pair of sheets or a halyard, is to buy them several meters longer than you need them to be, even accounting for the splice for the shackle. As when they begin to wear, you can chop off a meter or two, & throw in a new splice. But in cutting off that end, you’ll need a meter or three of line for the new splice.
Plus of course, you can end for end such lines, & then re-splice them as above.


From here, YOU need to talk to the cordage manufacturers, some riggers, & some chandleries, in order to form your own mental picture of what's best. As well as what types & diameters of line are readily available to you. It's just a bit of reading, & some phone calls. Oh, & again, go over to Sailing Anarchy Forums to add to your cordage IQ.

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