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Old 02-07-2009, 00:25   #1
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10oz Dacron Gaff Sails Thread Weight?

Does anyone know about thread weight and the maximum used for strong cruising sails? We are ordering 3 working sails which we hope will withstand Cape Horn. Our sailmaker has informed us that he uses '138 Hemmingway and Bartlett premium Dacron thread ' but we are wondering if a heavier thread will give us a stronger sail. What would be the maximum weight of thread possible on a low aspect gaff mainsail? Any ideas would be much appreciated. Cheers.
Charlie
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Old 02-07-2009, 03:15   #2
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Personally, I have no idea.

But I would be asking alternative sailmaakers, and also sailrite (the sailmaking sewing machine people)
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Old 02-07-2009, 10:29   #3
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V138 is perfect. It's as big as you can go without sewing trouble and at this size it's considered UV proof (thread outlasts sails).

go for it.

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Old 03-07-2009, 10:03   #4
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thankyou, (also destructive hypothetical)

Thanks a bunch for your ideas and opinions. We really want the strongest robust sails possible. The boat is a steel schooner with steel masts.. very solid. We want the sails to hang in there as long as possible in a gale. For instance, if one was to put the boat in a concrete pit, set all sail for a broad reach angle of wind .. and then... slowly rev up a pratt and whitney jet engine in the direction of wind flow.... what part of the sail or rig would fail first? 50 - 60 -70 -80 - 100knts .... what would happen exactly? Any ideas? I guess the sail would fail before the rig.. but... which part of the sail would fail first?.. Just a crazy hypothetical. Thanks.
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Old 03-07-2009, 20:53   #5
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When you try to break a V138 thread with your hands, it'll cut your fingers off before breaking.

about your hypothetical: your sails will burn.

cheers,
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Old 04-07-2009, 01:09   #6
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Sail destruction

sails will burn!! i like that...ok... instead of a jet engine... lets use a prop engine without too much heat. What would happen? thanks for your thoughts.
CHarlie
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Old 04-07-2009, 08:17   #7
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Okay ;-)

No heat: I am sure the rig will fail. all rigging is calculated for the forces needed for heeling the boat only, not to endure wind pressure.

This is exactly why multihulls have much more rigging problems.

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Old 04-07-2009, 08:59   #8
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Quote:
Originally Posted by s/v Jedi View Post
This is exactly why multihulls have much more rigging problems.

Lets have another dig at multihulls

If you had said "Thats why multihulls need heavier rigging" I would agree with you.

A Yacht designer has to take these things into account, thus a multihull designer would know that heavier rigging would be needed to handle the loads, just as the mast people know that you need to use a thicker (thus heavier) mast section for a multihull mast. AFAIK There is no % trend for multihulls to lose their mast more frequently than monos (disregarding racing boats) Assuming that rigging is being checked and replaced at appropriate timings.
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Old 04-07-2009, 11:05   #9
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destructive sail testing

Thanks for your reply. The rig would fail , ok, but let's say we make a super heavy duty steel rig bolted to the ground behind the prop engine. Oversize to the max, what part of the sail would give first? any ideas?
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Old 04-07-2009, 20:52   #10
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Charlie: ah, it's the part of the sail that fails first that you are interested in. That's a tough call because modern sails are designed to be stronger where the forces are higher. My tri-radial cut sails even use different weights cloth for different panels.

I have no clue what will go first so my guess is that it's at a random location. For old sails it's different, I would say along a seam or fold (folds break the coating).

Talbot: a multihull endures shock loading in the rig that isn't dampened much. On a mono hull the only shock loading is from slamming into seas, the rest is absorbed by heeling. This is the price the multihull design pays for not heeling. Shock loading leads to stress (fatigue, hairline cracks) in the stainless parts incl. the chainplates and their bolts. You don't see that on monohulls: almost all of their chainplate failures are due to crevice corrosion (lack of oxygen on the steel surface)

Relax, I think you're over-sensitive to my factual pointing out a weak point in the multihull which isn't needed because I would just as easily point out weaknesses in monohulls; I have nothing against initial stability. But the example of a monohull put in concrete is very similar (for the rig) to a multihull under sail so that's why I brought that up.

;-)

cheers,
Nick.
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