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Old 13-05-2016, 10:13   #31
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Re: Attaching Dyneema Sheets to Headsail Clew

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Originally Posted by Bor the Wolf View Post
First of, I would never use Dyneema for a sheet. It lacks the elastic dampening needed to cope with a header and also to offload my hands and arms. It is great stuff for a halyard, the sail once trimmed won't move. As an International OD racer I have yet to see a Dyneema sheet in the fleet.

The easiest way to attach a sheet to the Genoa: a bowline.
I also used a modified fishermans bend (through the clew). Modified by using a figure eight instead of a half hitch. (A figure eight knot unties easier after the race).
+1

This is also my understanding of sheet selection and the use of a bowline to attach the jib sheets as well.
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Old 13-05-2016, 11:09   #32
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Re: Attaching Dyneema Sheets to Headsail Clew

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+1

This is also my understanding of sheet selection and the use of a bowline to attach the jib sheets as well.
Then you understanding is wrong. Dyneema is the principle material for all lines on race boats, and nowhere is stretch considered an advantage (other than dock lines). The more a line stretches the less predictable the sail shape, and the more power is wasted on line friction. Modern race boats have moved almost exclusively to heat set dyneema (even less stretch than regular) with Technora or Kevlar covers to guard against heat and abrasion.

If stretch were desirable in sheets we would all be using bungie cord not rope anyway.
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Old 13-05-2016, 11:25   #33
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Re: Attaching Dyneema Sheets to Headsail Clew

Bit of thread drift, but I got to thinking about my rigging job at Spencers and looked up my old invoices.

To my surprise -- the expensive halyards were supposed to have been made out of Marlow D2 Racing 75. The ones which feel like loose tubes over the core.

To anyone with experience with these particular ropes, is there so much difference between the Racing 78 and older Racing 75?

My new ropes (sheets, and preventers) made with D2 Racing 78 are much, much nicer, with much tighter fitting cover and better hand. Chalk and cheese compared to the halyards. I wonder if I was cheated with something other than what I paid for?
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Old 13-05-2016, 12:00   #34
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Re: Attaching Dyneema Sheets to Headsail Clew

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I wonder if I was cheated with something other than what I paid for?

You should be able to tell if the old ones were actually d2 racing by the braid pattern - are they one of these patterns:
D2.

Edit if it's one of the solid colors it will not be definitive, but if it is not one of these patterns at all it is probably not d2

I don't have much experience with Marlow double braid . . . . But looking at their product info I would not have expected much difference in the cover between d2 75 and d2 78.
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Old 13-05-2016, 12:57   #35
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Re: Attaching Dyneema Sheets to Headsail Clew

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Then you understanding is wrong. Dyneema is the principle material for all lines on race boats, and nowhere is stretch considered an advantage (other than dock lines). The more a line stretches the less predictable the sail shape, and the more power is wasted on line friction. Modern race boats have moved almost exclusively to heat set dyneema (even less stretch than regular) with Technora or Kevlar covers to guard against heat and abrasion.

If stretch were desirable in sheets we would all be using bungie cord not rope anyway.
Sorry! I thought that this was a cruisers forum and not a racers forum.

On a cruising boat the sheet stretch is in fact desirable as it help absorb the shock loads due to changes in wind speed and direction.

Where, on a racing boat speed is of prime importance and the wear and tear due to shock loads is part of the cost of winning.
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Old 13-05-2016, 13:05   #36
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Re: Attaching Dyneema Sheets to Headsail Clew

Well, on my cruising boat, the last thing I want is stretch. When hit by a gust, I'd just assume my sails don't get fuller! Perhaps on you're boat it doesn't matter to you, but I think it's safe to say it does matter to quite a few "cruisers".


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Old 13-05-2016, 13:09   #37
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Re: Attaching Dyneema Sheets to Headsail Clew

^^
The principle trade-off is (1) high modulus = high shock loads vs (2) high modulus = better sailing performance. Cruisers vary in their desired trade-off between those two. High modulus is also high cost. It is not back/white, or one end of the spectrum of the other.

I would suggest usually anyone is incorrect if/when you say "this is the one best solution" for almost anything on a cruising boat. Usually there are multiple "best solutions" for different needs.
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Old 13-05-2016, 13:38   #38
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Re: Attaching Dyneema Sheets to Headsail Clew

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^^
The principle trade-off is (1) high modulus = high shock loads vs (2) high modulus = better sailing performance. Cruisers vary in their desired trade-off between those two. High modulus is also high cost. It is not back/white, or one end of the spectrum of the other.

I would suggest usually anyone is incorrect if/when you say "this is the one best solution" for almost anything on a cruising boat. Usually there are multiple "best solutions" for different needs.
Wise words.

"Shock loads" from gusts are not a problem if the gear is reasonably strong.

And chafe is increased, not decreased by stretchy lines.

But stretchy lines make the rig "softer", less sensitive to sail trim (i.e. impossible to really trim exactly right, so never really all that wrong) and so some people might like that.

But I think the overwhelming main issue is simply cost. Dyneema is expensive, and that was exactly whyI bought polyester sheets last time around, myself.
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Old 13-05-2016, 13:44   #39
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Re: Attaching Dyneema Sheets to Headsail Clew

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Well, that "elastic dampening" is spilling wind from your sail while "panting", and is dissipating energy. Stretch is not desirable either in sheets, halyards, or indeed in sails. I don't know what "International OD" racing is, but I spend half the year in Cowes every year, and I haven't seen a polyester sheet on a racing boat in years, maybe decades. The racers here like to strip the cover off the non-handled part of their Dyneema sheets, to reduce windage. For cruisers of course this is not such a big deal, and I was using polyester sheets even with carbon laminate sails until now. But no question Dyneema is better.
ss
.
better for... !?

I have Dyneema 78 for halyards only, by Gottifredi&Maffioli
An absolute necessity on a 70'+ halyard, were 1% elongation is 20cm.

They are quite harsh and rugged to touch, i need gloves to pull them up.

I feel very comfortable with polyester sheets, just paying 2mm more D vs dyneema.

Maybe, too many racers in Cowes!? :-)
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Old 13-05-2016, 16:14   #40
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Re: Attaching Dyneema Sheets to Headsail Clew

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Well, that "elastic dampening" is spilling wind from your sail while "panting", and is dissipating energy. Stretch is not desirable either in sheets, halyards, or indeed in sails. I don't know what "International OD" racing is, but I spend half the year in Cowes every year, and I haven't seen a polyester sheet on a racing boat in years, maybe decades. The racers here like to strip the cover off the non-handled part of their Dyneema sheets, to reduce windage. For cruisers of course this is not such a big deal, and I was using polyester sheets even with carbon laminate sails until now. But no question Dyneema is better.


Concerning attachment -- I agree about bowlines, when you're talking about polyester sheets. Works great, simple, doesn't snag, secure, reasonably strong. I've always done this on all of my boats.

The problem here is that Dyneema can't be safely or securely knotted. Otherwise I would continue using bowlines.
Now that you mention it, my sheets are dyneema as well. And they have their covers stripped (your remark triggerd my brain). I have gotten so used to those sheets that I totally forgot they are indeed Dyneema. BTW the core is 12 strand Dyneema and I have no trouble putting a bowline in it. If I remember correctly, they were made by Marlow.

As a racer you should know what OD stands for, its the only true racing there is! "One Design". First one to finish wins. No complex calculations and lots of fun at the marks where the entire fleet arrives almost at the same time. I tried handicap racing but I don't like it. It lacks the dynamics and tactics of one design racing. Handicap racers start together and when they meet again it's at the bar of the club. Where is the fun in that?
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Old 13-05-2016, 17:59   #41
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Re: Attaching Dyneema Sheets to Headsail Clew

Love my dyneema sheets. Went from 5/8" polyester to 7/16" warpspeed. Much easier to handle. No need for light air sheets, as they weigh next to nothing.
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Old 13-05-2016, 20:11   #42
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Re: Attaching Dyneema Sheets to Headsail Clew

Bro,

Estar has tested it, but knots in dyneema greatly reduce the strength of the line. For bolen I think at around 20% MBL the knot will just slip. I would highly recommend putting a quick eye splice in the tapered end and swapping to soft shackles to attach them.

One of the nice things of dyneema is that it can be spliced even after being used, unlike most double braided stuff.
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Old 13-05-2016, 23:50   #43
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Re: Attaching Dyneema Sheets to Headsail Clew

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Sorry! I thought that this was a cruisers forum and not a racers forum.
Anywhere, any place, any time, when two cruisers meet on a parallel course, guess what happens........
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Old 14-05-2016, 00:26   #44
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Re: Attaching Dyneema Sheets to Headsail Clew

As a recovering racer I can tel you from first hand experience that, at least in the US, I haven't seen a polyester line on a race boat in years. Everything that isn't dyneema or dyneema blend is vectran (which I don't recommend for cruising boats BTW). Our boat doesn't have a single low tech line on it other than dock lines and the anchor line. If you find that full dyneema lines are too thin to comfortably handle, they make blended core lines as low stretch, where they bulk up the dyneema core with polypro or similar.

On a headsail I think dyneema is always the preferred solution, especially if your sails are a little stretchy. I do think the main needs some give somewhere, but Evans' solution of having a stretchy traveler makes a lot of sense to me. I strongly recommend low stretch lines for main halyard, outhaul, and reef lines.

Places I think using a low tech line (e.g. Sta-Set or XLS) is a good idea on a cruising boat: storm jib and trysail sheets (for shock loading), spinnaker sheets, and if you're worried about jib shock loading you can always use it on the car adjusters to provide a little stretch.

The better and improved soft shackles are absolutely awesome. I have a bunch of J-locks and Tylaskas in fishing tackle boxes since I've replaced all my sheet shackles with soft shackles I made, mostly using the better soft shackle instructions. The ones on my RF jib haven't been off in two years and have never even shown signs of coming loose, plus no more J-locks banging around and sometimes coming undone. Bare spectra is nicely slippery naturally so it really helps keep things from hanging up.
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